Dissertations / Theses on the topic 'Polyandry'

Abstract Sexual selection results from competition between individuals over access to gametes of the opposite sex. Starting with anisogamy, with females producing larger and fewer gametes than males, females usually invest more in reproduction and thus have lower potential reproductive rates than males. Therefore males are traditionally suggested to compete over females whereas females are choosy. The different evolutionary interests between the sexes result in different selection regimes considering e.g. mating rates. In some species, this conflict is even seen as apparent struggles between males and females over mating decision and/or duration, resulting in antagonistic coevolution with both sexes evolving adaptations to gain more control over the other sex. In this thesis, I studied the role of A. paludum female abdominal spines as an adaptation to reject male mating attempts. I studied both the effect of polyandry and multiple matings on female fecundity to distinguish between the potential material and genetic benefits from mating to females. I also explored the role of various male and female morphological traits on precopulatory sexual selection and the consequent female reproductive output. My results show that female abdominal spines are likely evolved through arms races between the sexes to increase female control over mating decision but according to my studies, female spines are not under active selection. Instead, certain male morphological types were more successful in achieving matings, and mating with these males also increased female fecundity. I found that multiple matings increase female fecundity up to a point, supporting a theory of optimal female mating rate. According to my results, the benefits from multiple mating to A. paludum females result from material origin whereas polyandry per se is even detrimental to female fecundity
Tiivistelmä Seksuaalivalinta on pohjimmiltaan seurausta yksilöiden välisestä, lisääntymiseen liittyvästä kilpailusta toisen sukupuolen sukusoluista. Seksuaalivalinta on evoluutiomekanismi, joka osaltaan on johtanut sukupuolten välisiin eroihin monissa morfologisissa ja käyttäytymiseen liittyvissä ominaisuuksissa. Sukupuolet eroavat jo siinä, että naaraat tuottavat vähemmän mutta suurempia sukusoluja kuin koiraat. Koska sukupuolet siis investoivat lisääntymiseen jo alkuvaiheessa eri tavalla, niiden välillä on aina jonkin asteinen seksuaalikonflikti. Konfliktin taustalla on sukupuoliin kohdistuva erilainen valintapaine; koiraat saavuttavat usein optimaalisen hedelmällisyytensä suuremmilla parittelujen määrällä kuin naaraat. Joillakin eläinlajeilla seksuaalikonflikti on niin ilmeinen, että se ilmenee koiraan ja naaraan välisinä kamppailutilanteina parittelupäätöksen ja/tai parittelun keston suhteen. Seksuaalikonflikti voi johtaa molemmilla sukupuolilla erilaisiin sopeumiin, jotka lisäävät yksilön kontrollia parittelujen suhteen. Tässä väitöskirjatyössä tutkin naaraan takapäässä sijaitsevien abdominaalisten piikkien merkitystä järvivesimittari A. paludum-naaraiden kyvyssä torjua parittelemaan pyrkiviä koiraita. Tutkin myös polyandrian ja toistuvien parittelujen vaikutusta naaraan hedelmällisyyteen saadakseni selville, lisäävätkö koiraasta johtuvat mahdolliset materiaaliset tai geneettiset tekijät naaraan hedelmällisyyttä. Lisäksi selvitin useiden koiraan ja naaraan morfologisten ominaisuuksien yhteyttä parittelua edeltävään seksuaalivalintaan sekä naaraan hedelmällisyyteen. Tulokseni osoittavat, että naaraan abdominaaliset piikit ovat todennäköisesti kehittyneet seksuaalikonfliktin seurauksena lisäämään naaraan kontrollia parittelupäätöksen suhteen. Niihin ei kuitenkaan nykyisellään näytä kohdistuvan merkittävää valintapainetta. Sen sijaan morfologialtaan tietynlaiset koirastyypit vaikuttavat olevan aktiivisen valinnan kohteena ja parittelu tällaisten koiraiden kanssa lisää myös naaraan hedelmällisyyttä. Toistuvat parittelut saman koiraan kanssa lisäävät naaraan hedelmällisyyttä tiettyyn optimiin asti, mikä tukee teoriaa optimaalisesta parittelujen määrästä. Sen sijaan polyandria itsessään vaikuttaa naaraan hedelmällisyyteen jopa heikentävästi. Niinpä A. paludum-naaraiden saama hyöty useista paritteluista näyttää olevan materiaalista, kun taas polyandriasta saatavia geneettisiä etuja ei tässä tutkimuksessa tullut ilmi

[Truncated abstract] Despite the costs associated with mating, females of many taxa solicit multiple mates during a single reproductive event (polyandry). Polyandry is clearly adaptive when females gain direct benefits from males at mating. However, polyandry has also been shown to increase female fitness in the absence of direct benefits. Thus, a number of genetic benefit hypotheses have been developed to account for the origin of this behaviour. Although not mutually exclusive, a distinction lays between genetic benefits that propose defense against reproductive failure (nonadditive genetic effects), and those that propose benefits from intrinsic sire effects (additive genetic effects). Nonadditive genetic benefits of polyandry have been documented in a number of species; by soliciting multiple mates females can avoid inbreeding and other forms of incompatibility between parental genotypes. Polyandry may also increase female reproductive success when genetically superior males have greater success in sperm competition, and produce better quality offspring. An inevitable consequence of polyandry is that sperm from rival males will overlap in the female reproductive tract and compete to fertilise the ova. The outcome of sperm competition is typically determined by bias in sperm use by the females, interactions between parental genotypes, and ejaculate characteristics that provide a fertilisation advantage. Thus, sperm competition is recognised as a persuasive force in the evolution of male reproductive traits. Comparative analyses across species, and competitive mating trials within species have suggested that sperm competition can influence the evolution of testis size and sperm production, and both sperm form and sperm function. ... After six generations of selection I observed phenotypic divergence in litter size - litter size increased in the polyandrous lines but not in the monandrous lines. This result was not attributable to inbreeding depression, or environmental/maternal effects associated with mating regime. Genetic benefits associated with polyandry could account for this result if increased litter size were attributable to increased embryo survival. However, males from the polyandrous lineages were subject to sperm competition, and evolved ejaculates with more sperm, suggesting that evolutionary increases in litter size may in part be due to improved male fertility. Finally, Chapter Five is an investigation of the natural variation in levels of polyandry in the wild, and the potential for sperm competition to drive macroevolutionary changes in male reproductive traits among geographically isolated island populations of house mice. I sampled seven island populations of house mice along the coast of Western Australia and, by genotyping pregnant females and their offspring, determined the frequency of multiply sired litters within each population. I applied the frequency of multiple paternity as an index of the risk of sperm competition, and looked for selective responses in testis size and ejaculate traits. I found that the risk of sperm competition predicted testis size across the seven island populations. However, variation in sperm traits was not explained by the risk of sperm competition. I discuss these results in relation to sperm competition theory, and extrinsic factors that influence ejaculate quality.

Thesis (Ph. D.)--Illinois State University, 2005.
Title from title page screen, viewed April 12, 2007. Dissertation Committee: Scott K. Sakaluk (chair), Diane L. Byers, Steven A. Juliano, Sabine S. Loew, William L. Perry. Includes bibliographical references (leaves 96-114) and abstract. Also available in print.

Elaborate sexual ornaments evolve because mate choice exerts strong sexual selection favouring individuals with high levels of ornament expression. Consequently, even at evolutionary equilibrium, life history theory predicts that ornamental traits should be under directional sexual selection that opposes contrasting selection to reduce the costs associated with their maintenance. Otherwise, the resources used to maintain ornaments should be used to improve other life history functions. Elaborate female ornaments have only evolved in a few species, despite females commonly experiencing strong sexual selection. One explanation for this rarity is that male preferences for female ornaments may be self-limiting: females with higher mating success become less attractive because of the lower paternity share they provide to mates with every additional sperm competitor. The unusual species in which female ornaments do occur can provide rare insight into how selection can favour the expression of expensive characters in females despite their costs. The main goal of my thesis was to determine how sexual selection acts on exaggerated sexual ornaments, and give new insight into how these ornaments may have evolved, in spite of the self-limiting nature of selection on male preferences. To determine the strength of sexual selection acting on female ornamentation in dance flies, we developed new microsatellite markers to assess polyandry rates by genotyping stored sperm in wild female dance flies. We first used polyandry rates to determine whether ornament expression was associated with higher mating success in female Rhamphomyia longicauda, a species that has evolved two distinct and exaggerated female ornaments. Contrary to our predictions, we found no evidence that females with larger ornaments enjoy higher mating success. We then compared polyandry rates in R. longicauda to those of two other species of dance fly, one (Empis aestiva) that has i independently evolved female ornaments on its legs, and another (E. tessellata) that does not possess any discernable female ornaments. We also estimated the opportunity for sexual selection, which we found to be similar and relatively low in all three species. Moreover, the standardized sexual selection gradients for ornaments were weak and non-significant in all three species. Females with more elaborate ornaments, in both within- and cross-species comparisons, therefore did not enjoy higher mating success. Overall, these results suggested that sexual selection operates rather differently in females compared to males, potentially explaining the general rarity of female ornaments. Our amplifications of stored sperm were able to reveal more than just mate numbers. We developed new methods to study patterns of sperm storage in wild female dance flies. We investigated how the skew in sperm genotypes from mixed sperm stores changed with varying levels of polyandry. Our data suggested that sperm stores were dominated by a single male in R. longicauda, and that the proportion of sperm contributed by this dominant male was largely independent of the number of rival males’ sperm present in the spermatheca. These results were consistent with the expectation of males using sperm ‘offence strategies’ in sperm competition and that the most successful male is likely to be the female’s last partner before oviposition. As a whole, my thesis contributed new molecular resources for an understudied and fascinating group of organisms. It exploited these new resources to provide the first estimates of lifetime mating success in several related species, and suggested that the general prediction that ornament expression should covary with sexual selection intensity does not seem to hold in this group. Instead, both the unusual prevalence of ii ornaments and the inconsistent evidence for sexual selection that sustains them in dance flies may owe their existence to the confluence of two important factors. First, the conditions under which sperm competition occurs: as last male precedence is likely, males are selected to prefer the most gravid females to secure a high fraction of her offspring’s paternity as they are unlikely to mate again before oviposition. Second, potent sexually antagonistic coevolution between hungry females and discerning males: females have evolved ornaments to disguise their stage of egg maturity to receive the benefits of nuptial gifts, while males face the challenge of distinguishing between gravidity and ornamentation in females.

Behavioral studies in the green turtle (Chelonia mydas) have indicated that promiscuous mating is commonplace. Though it has been shown that there is much variation in the rate of polyandry (females mating with multiple males), the drivers behind polyandry in this species are unknown. It has been speculated, but never demonstrated, that indirect benefits (fitness benefits resulting from offspring genetic diversity) play a role. However, previous tests of this hypothesis have limited scope of inference due to lack of environmental control. In this thesis, I attempted to study the indirect benefits of polyandry in Archie Carr National Wildlife Refuge (ACNWR) green turtles, limiting environmental variation by selecting nests over two week periods in a small subset of the ACNWR. Through the use of highly polymorphic microsatellite markers, I show that 85.7% of ACNWR green turtle females mate with multiple males, the highest rate yet reported for green turtles. I was successful in limiting environmental variation; however, I was unable to make comparisons among nests with one or multiple fathers because of a limited sample size of single father nests. Regardless, my thesis provides preliminary evidence (number of males per nest) that the density of males off Florida's beaches may be relatively high, which is expected to be a driver behind the evolution of polyandry and likely plays a large role both in this population and the prevalence of multiple paternity in green turtles as a whole.
M.S.
Masters
Biology
Sciences
Biology

Sexual selection is responsible for the evolution of formidable adaptations across the tree of life. Traditionally, sexual selection research has focused on male sexual displays and female choice. However, this approach ignores important social and environmental factors that can influence the operation of sexual selection. In this thesis, I aim to contribute to our knowledge of the effects of social and environmental factors, particularly those related to nutrition, on sexual selection. I investigate how the sexual behaviour of females and the nutritional and social environments of both sexes during larval and adult stages modulate sexual selection in the fruit fly Drosophila melanogaster. First, I assess how female promiscuity ("polyandry") affects the strength of sexual selection and patterns of assortative mating in freely interacting populations. There is no current consensus for the conflicting results of previous studies showing that polyandry can have positive, negative or have negligible effect on the opportunity for sexual selection. Using a genetic knockout that increases female sexual receptivity, I show that increasing polyandry reduces the opportunity for sexual selection and shifts the relative role of sexual selection from pre- to post-copulatory in males without affecting assortative mating patterns in freely interacting populations. Next, I consider how plastic responses to nutritionally poor larval environments and adult social environments modulate sexual selection, an area that has been considerably ignored. I find that although nutritionally poor larval environments reduce individuals' mating and reproductive success, plastic responses to social environments might mitigate against these disadvantages. Moreover, I show that plastic responses to larval and social environments influence the relative role of pre- and post-copulatory sexual selection in males, regulate offspring traits through trans-generational effects and determine population fate. Finally, I consider whether male reproductive traits have distinct macronutrient (protein and carbohydrate) requirements, and whether males can regulate their feeding to attain a diet that satisfies the requirements for these traits. I find that both a high short-term rate of offspring production when males mate with virgin females, and a high total number of offspring sired when males mate with previously mated females, require carbohydrate-rich diets, whereas male attractiveness requires a balanced (1:1) macronutrient diet. Furthermore, I show that male protein intake can negatively affect female long-term reproduction when males mate with virgins, but not with previously mated females, revealing a novel intersexual effect of male nutrition. Thus, this thesis deepens our understanding of key evolutionary processes by revealing the negative effects of high polyandry and nutritionally poor larval environments on the operation of sexual selection as well as uncovering male nutritional compromise in the expression of reproductive traits.

Abstract Female ability to exploit conspecifics in reproduction may have unusual expressions. I studied the reproductive behaviour of the golden egg bug (Phyllomorpha laciniata; Heteroptera, Coreidae) experimentally in the field and in the laboratory. Female golden egg bugs lay their eggs mainly on the backs of conspecific males and other females. Non-parental eggs are often carried. Occasionally, the eggs are laid on the food plant (Paronychia spp; Polycarpea, Caryophyllaceae) of the species but typically, those eggs survive poorly due to egg parasitism and predation. I explored the dependence of female reproduction on conspecific presence and encounter rate. I also studied female current reproductive state (which depends on if she has recently oviposited) in relation to her activity as well as male choice of a female. Female bugs preferred to oviposit on conspecifics when presented with a choice between a bug and a food plant. When alone females often did not lay eggs. Increased encounter rate with others increased female egg laying rate. Survival of carried eggs among bugs did not vary significantly although males received more eggs than females. Females with high current fecundity (mature eggs accumulated to reproductive tract) were more active than females with lower current fecundity (recently oviposited). Females with high current fecundity seemed to search for conspecifics to lay eggs on. Males also preferred to court females with high current fecundity. These females were more likely to oviposit immediately after mating, lowering the risk of female remating before oviposition. To conclude, conspecifics are important egg-laying substrates for female golden egg bugs. Conspecific availability affects female egg laying and the rate of egg production in short term. In particular, males are necessary for egg-laying females and they typically receive unrelated eggs when they court females. Sexual interactions resulting from female polyandry are crucial factors that maintain female egg laying on the backs of males and other females in the unique reproductive system of the golden egg bug.

Although sexual stereotypes paint males as being promiscuous and females as being choosy in order to increase their reproductive success, multiple mating by females is widespread and females of many taxa often produce progeny sired by multiple males – but why? In species in which there are no direct benefits associated with mating, females may adopt promiscuous mating strategies to increase their fitness through the acquisition of genetic benefits. Here, I examine the genetic mating system of map turtles, Graptemys geographica in Lake Opinicon. Based on the most conservative estimate, at least 71% of clutches in this population are sired by multiple males. There did not appear to be any relationship between female body size and frequency of multiple paternity. There was a marginally significant effect of multiple paternity on hatching success and survival of clutches, but there was no effect on hatchling morphology or locomotor performance.

The protection of species is one major focus in conservation biology. The basis for any management concept is the knowledge of the species autecology. In my thesis, I studied the life-history traits and population dynamics of the endangered Lesser Spotted Woodpecker (Picoides minor) in Central Europe. Here, I combine a range of approaches, from empirical investigations of a Lesser Spotted Woodpecker population in the Taunus low mountain range in Germany, the analysis of empirical data and the development of an individual-based stochastic model simulating the population dynamics.

In the field studies I collected basic demographic data of reproductive success and mortality. Moreover, breeding biology and behaviour were investigated in detail. My results showed a significant decrease of the reproductive success with later timing of breeding, caused by deterioration in food supply. Moreover, mate fidelity was of benefit, since pairs composed of individuals that bred together the previous year started earlier with egg laying and obtained a higher reproductive success. Both sexes were involved in parental care, but the care was only shared equally during incubation and the early nestling stage. In the late nestling stage, parental care strategies differed between sexes: Females considerably decreased feeding rate with number of nestlings and even completely deserted small broods. Males fed their nestlings irrespective of brood size and compensated for the females absence. The organisation of parental care in the Lesser Spotted Woodpecker is discussed to provide the possibility for females to mate with two males with separate nests and indeed, polyandry was confirmed.

To investigate the influence of the observed flexibility in the social mating system on the population persistence, a stochastic individual-based model simulating the population dynamics of the Lesser Spotted Woodpecker was developed, based on empirical results. However, pre-breeding survival rates could not be obtained empirically and I present in this thesis a pattern-oriented modelling approach to estimate pre-breeding survival rates by comparing simulation results with empirical pattern of population structure and reproductive success on population level. Here, I estimated the pre-breeding survival for two Lesser Spotted Woodpecker populations on different latitudes to test the reliability of the results.

Finally, I used the same simulation model to investigate the effect of flexibility in the mating system on the persistence of the population. With increasing rate of polyandry in the population, the persistence increased and even low rates of polyandry had a strong influence. Even when presuming only a low polyandry rate and costs of polyandry in terms of higher mortality and lower reproductive success for the secondary male, the positive effect of polyandry on the persistence of the population was still strong.

This thesis greatly helped to increase the knowledge of the autecology of an endangered woodpecker species. Beyond the relevance for the species, I could demonstrate here that in general flexibility in mating systems are buffer mechanisms and reduce the impact of environmental and demographic noise.
Der Schutz von Arten ist eine der Hauptaufgaben des Naturschutzes. Für die Erstellung von Schutzkonzepten sind Informationen zur Autökologie der Zielart notwendige Voraussetzung. Der Kleinspecht (Picoides minor) ist in vielen Teilen seines Verbreitungsgebietes bestandsbedroht, das Wissen zur Biologie und Verhalten der Art ist jedoch lückenhaft. Ziel meiner Arbeit war es daher, demographische Parameter der Populationsdynamik des Kleinspechts zu erfassen, die als Grundlage für Populationsgefährdungsanalysen benötigt werden. Da Untersuchungen in Schweden eine gewisse Flexibilität im Paarungssystem des Kleinspechts zeigten, sollte darüber hinaus das Paarungssystem und sein Einfluss auf die Persistenz der Population untersucht werden.

Die Arbeit umfasste eine Reihe von methodischen Ansätzen, von empirischen Untersuchungen an einer Kleinspechtpopulation im hessischen Vordertaunus über die Aufbereitung von empirischen Daten bis hin zur Entwicklung und Auswertung eines stochastischen individuenbasierten Modells zur Simulation der Populationsdynamik.

Die Ergebnisse der empirischen Untersuchung zeigten eine Abnahme des Reproduktionserfolgs mit fortschreitendem Legebeginn. Die Zusammensetzung der Nestlingsnahrung ließ vermuten, dass dies durch eine Verschlechterung der Nahrungsversorgung begründet war. Paartreue war bei der Reproduktion von Vorteil, da Individuen, die schon im vorherigen Jahr zusammen gebrütet hatten, einen früheren Legebeginn und damit einen höheren Fortpflanzungserfolg aufwiesen als neu formierte Paare. Beide Geschlechter investierten in die Brutpflege, jedoch war die Aufteilung nur während der Bebrütung der Eier und in der ersten Hälfte der Nestlingsperiode gleichmäßig. In der späten Nestlingsperiode konnten geschlechtsspezifische Strategien im elterlichen Investment identifiziert werden: die Weibchen verringerten die Versorgungsrate in Abhängigkeit des Wertes der Brut - gemessen in der Zahl der Nestlinge - und gaben die Versorgung kleiner Bruten ganz auf. Die Männchen dagegen kompensierten dieses Verhalten, so dass auch von den Weibchen verlassene Bruten erfolgreich waren. Interessanterweise konnte mehrmals die Verpaarung von einem Weibchen mit zwei Männchen beobachtet werden. Das Auftreten dieses polyandrischen Paarungssystems wird in der Arbeit als Resultat der Aufteilung der Brutpflege diskutiert.

Die bestätigte Flexibilität im Paarungssystem könnte Einfluss auf die Persistenz der Population haben. Die Persistenz von Populationen kann jedoch nicht empirisch gemessen werden. Daher entwickelte ich ein individuen-basiertes stochastisches Modell zur Simulation der Populationsdynamik des Kleinspechts, dass auf den empirischen Daten basiert. Allerdings fehlten Überlebensraten der ausgeflogenen Jungvögel, die im Feld nicht ermittelt werden kann. Daher testete ich hier eine Methode, die durch den Vergleich von Simulationsergebnissen mit eigenen empirischen Daten zur Populationsstruktur und zum Reproduktionserfolg auf der Ebene der Gesamtpopulation die Überlebensrate der Jungvögel abschätzt. Die Überlebensraten wurde zusätzlich für eine Population des Kleinspechtes ermittelt, deren Datengrundlage aus Freilandstudien in Schweden stammten. Durch den Vergleich der Raten für die beiden Populationen konnte die Aussagefähigkeit des Modells und die Güte der Abschätzungen untersucht werden. Im letzten Teil meiner Arbeit nutzte ich das Modell schließlich, um die Auswirkungen des Paarungssystems auf die Überlebensfähigkeit der Population zu untersuchen. Im Modell konnte ein Weibchen polyandrisch sein, wenn es gute Brutbedingungen hatte und das Geschlechterverhältnis zum Männchen hin verschoben war. Zusätzlich variierte ich die Wahrscheinlichkeit, dass unter diesen Umständen Polyandrie auftritt. Im Model wurden 3 Szenarien getestet: (i) strenge Monogamie, (ii) gelegentliche Polyandrie und (iii) gelegentliche Polyandrie unter der Annahme von Kosten für das sekundäre Männchen in Form von höherer Mortalität und geringerem Reproduktionserfolg. Es zeigte sich, dass selbst sehr geringe Polyandrieraten und die Annahme von Kosten noch einen deutlichen positiven Einfluss auf die Persistenz der Population ausüben. Die Flexibilität im Paarungssystem dient damit als Puffermechanismus gegen demographisches Rauschen und Umweltrauschen.

Diese Arbeit trät dazu bei, die Autökologie des Kleinspechts besser zu verstehen und ist damit wichtige Grundlage für Schutzkonzepte in Mitteleuropa. Über die artspezifische Bedeutung hinaus, leistet die Arbeit einen Beitrag zur Untersuchung von Methoden zur Abschätzung fehlender demographischer Parameter sowie zur Identifizierung von Puffermechanismen. Eine wichtige Schlussfolgerung meiner Arbeit ist es, dass die Flexibilität artspezifischen Verhaltens in zukünftigen Populationsgefährdungsanalysen integriert werden sollte, um die Qualität von Prognosen zur Persistenz von Populationen zu verbessern.

Abstract Females may either mate with one (monandry) or several (polyandry) males during a single breeding season. The polyandrous mating system has prompted numerous studies since the recognition of a widespread occurrence of mixed paternity among animals. Consequently, the benefits of polyandry have become well-established, and the female role in sexual selection upgraded. Females may gain both material and genetic benefits from multiple mating. Hence, the occurrence of polyandry is understandable, whereas monandry remains an evolutionary puzzle especially among species with male nutrient provisioning. I studied both the life history variation among female mating tactics and the adaptive significance of monandry in varying environmental conditions in the green-veined white butterfly [Pieris napi, (L. 1758)], which is a predominantly polyandrous species with nuptial feeding. I used a combination of explicit laboratory experiments and field studies. My results show that monandry and degrees of polyandry are distinct strategies with life history differences reaching beyond mating frequencies. Polyandry corresponded with a higher lifetime fecundity than monandry in P. napi. Polyandry was, however, associated with relatively low fecundity during the early days of reproduction. Thus, monandry is beneficial if time for reproduction is limited severely enough or other female traits or behaviours associated with polyandry are traded off against longevity. Due to temporal variation in reproductive rate among mating tactics, offspring of polyandrous females have less time to complete development. Accordingly, polyandrous females developed at a faster rate as larvae than monandrous ones under optimal conditions. Despite growth rate variation, monandrous females were more likely to contribute to additional summer generation in conditions that allow production of only a partial second generation, and thus monandry is favoured under these conditions. Genetic variation in female mating tactics will not only prevail if environmental conditions do not allow all individuals to contribute evenly to the directly breeding generation in bivoltine populations, but also if even the production of a single generation per year is time-limited. A general conclusion would be that seasonality and unpredictability of fitness in the wild drives the evolution of optimal female mating tactics and promotes the maintenance genetic variation in mating frequencies, regardless of the direct benefits of nuptial feeding. Even if a high degree of polyandry would be the most profitable mating tactic in an average year, strong annual variation in weather conditions and the duration of summer may create possibilities for a temporally fluctuating selection that promotes a co-existence of different mating tactics because variance of fitness is likely increase with an increasing mating frequency.

Postmodern worldview requires a change of focus on the place and role of the traditional social institutions and habitual behaviors within them. The latest researches state that significant differences in attitudes towards sex were found among different generations. B. Christlieb explored sexual attitudes through the lens of family sexual communication and demographic factors

Postmodern worldview requires a change of focus on the place and role of the traditional social institutions and habitual behaviors within them. The latest researches state that significant differences in attitudes towards sex were found among different generations. B. Christlieb explored sexual attitudes through the lens of family sexual communication and demographic factors

Postmodern worldview requires a change of focus on the place and role of the traditional social institutions and habitual behaviors within them. The latest researches state that significant differences in attitudes towards sex were found among different generations. B. Christlieb explored sexual attitudes through the lens of family sexual communication and demographic factors

Honey bees (Apis mellifera) are the most economically important insect pollinator of agricultural crops in the United States. Honey bee colonies are required for pollination of approximately one-third of the nation’s fruit, vegetable, nut, and forage crops, with an estimated annual value in the billions of dollars. The economic value of a honey bee colony comes from its population size, as large colonies provide the necessary foraging force required for large-scale crop pollination services. A major component of colony strength is its genetic diversity, a consequence of the reproductive mating strategy of the queen known as polyandry. Despite some inherent risks of multiple mating, several studies have demonstrated significant advantages of intracolonial genetic diversity for honey bee colony productivity. Colony-level benefits include better disease resistance, more stable brood nest thermoregulation, and greater colony growth. Instrumental insemination of honey bee queens is a technique to precisely control queen mating, and thereby creates the opportunity to investigate the effects of intracolonial genetic diversity on colony performance. In this dissertation, I first consider the effects of intracolonial genetic diversity on pollen foraging using colonies headed by queens which were instrumentally inseminated with either one or twenty drones to generate colonies of very high or very low intracolonial genetic diversity, respectively. I found that colonies with high intracolonial genetic diversity amass significantly more pollen and rear more brood than colonies with low intracolonial genetic diversity. Of particular interest, colonies with low intracolonial genetic diversity collected a significantly greater variety of pollen types. I discuss these results in the context of scouting and recruiting, and suggest a more efficient foraging strategy exists among genetically diverse colonies. While intracolonial genetic diversity is positively correlated with collected pollen, its effect on the colony’s ability to process and distribute inbound protein resources is unknown. Again using colonies headed by queens instrumentally inseminated with either one or twenty drones, I studied the effects of intracolonial genetic diversity on pollen consumption and digestion by nurse bees, as well as protein allocation among nestmates by assessing total soluble protein concentration of late instar larvae, and total soluble hemolymph protein concentration in both nurses and pollen foragers. I found that nurse bees from colonies with high intracolonial genetic diversity consume and process more protein than nurses from colonies with low intracolonial genetic diversity, even when given equal access to protein resources. Further, both forager hemolymph protein concentrations and larval total protein concentrations were higher among the colonies with high intracolonial genetic diversity. My findings suggest that protein processing and distribution within a honey bee colony is affected by the social context of the hive. I discuss “worker policing”, and the role of nurse bees in modulating the foraging effort. Finally, I assess the standing genetic variability among several colonies sourced from different genetic and geographic locations. Using microsatellite DNA from workers sampled from each colony, I determined allelic richness, gene diversity, and effective mating frequency for each genetic line. I found differences in all three metrics between lines, and for one line in particular, there was no correlation with genetic variation and effective mating frequency, suggesting non-random mating. My results showed very different levels of intracolonial genetic diversity among naturally mated queens. Because of its impact on colony performance, the importance of maintaining genetic diversity in breeding populations is discussed.

Abstract Both the length of the season that is favourable for insect growth and reproduction and the number of generations emerging per season (voltinism) increase with decreasing latitude. Thus, time constraints on reproduction and juvenile development decrease with decreasing latitude, except where voltinism changes and time constraints suddenly increase as the season must be shared with one more generation. I studied the evolution of insect life histories in relation to time constraints from two perspectives: polymorphism and clinal variation. Life history polymorphism in seasonal environments was studied with the butterfly Pieris napi that has discrete life history strategies, and polymorphic natural populations. Experimental studies showed that asymmetric intraspecific larval competition and divergent timing of reproduction between the strategies may promote the maintenance of polymorphism. A simulation model showed that the divergent timing of reproduction between the strategies is sufficient to maintain polymorphism even in the absence of intraspecific competition. Clinal variation was studied empirically with four geometrid moths (Cabera exanthemata, Cabera pusaria, Chiasmia clathrata and Lomaspilis marginata) and generally in theory. Due to latitudinal saw-tooth variation in time constraints, traditional theory predicts a saw-tooth cline in body size and development time. A common garden experiment with the four geometrid moths did not support the traditional theory even when a saw-tooth cline in body size was found, suggesting that the theory is based on unrealistic assumptions. A theoretical analysis showed that reproductive effort should be high in populations under intense time constraints and low in populations experiencing no time constraints, resulting in a saw-tooth cline. In the four geometrid moths, support for these predictions was found, although the observed clinal variation deviated from the predicted pattern. The results imply that clinal variation is expected in almost any continuous life history trait, whereas polymorphism of different strategies may emerge when life histories fall into discrete categories. When inferring the evolution of a single trait, complex interdependencies among several traits should be considered, as well as the possibility that the time constraints are not similar for each generation in multivoltine populations
Tiivistelmä Hyönteisten kasvu ja kehitys ovat pääsääntöisesti mahdollisia vain kesän aikana. Etelään päin mentäessä kesä pitenee, ja saman kesän aikana kehittyvien hyönteissukupolvien määrä kasvaa. Kesän pituus aiheuttaa lisääntymiseen ja toukkien kasvuun kohdistuvan aikarajoitteen, joka heikkenee etelään päin siirryttäessä. Aikarajoite kuitenkin tiukkenee siellä, missä yksi uusi sukupolvi ehtii juuri kehittymään saman kesän aikana, sillä kesä on nyt jaettava useamman sukupolven kesken. Väitöstyössä tarkastelin hyönteisten elinkierto-ominaisuuksien evoluutiota suhteessa aikarajoitteisiin sekä diskreetin että jatkuvan muuntelun näkökulmista. Diskreettiä muuntelua tutkin lanttuperhosella (Pieris napi), jolla esiintyy diskreettejä elinkiertostrategioita. Kokeellisesti osoitin, että toukkien välinen kilpailu on epäsymmetristä, mikä yhdessä eri elinkiertostrategioiden erilaisen lisääntymisen ajoittumisen kanssa voi ylläpitää diskreettiä muuntelua. Simulaatiomalli osoitti, että erilaiset elinkiertostrategiat voivat säilyä populaatiossa pelkästään niiden erilaisen lisääntymisen ajoittumisen ansiosta. Elinkierto-ominaisuuksien jatkuvaa muuntelua tutkin neljän mittariperhosen (Cabera exanthemata, Cabera pusaria, Chiasmia clathrata ja Lomaspilis marginata) avulla ja teoreettisesti yleisellä tasolla. Aikaisempi teoria ennustaa ruumiinkoon ja kehitysajan muuntelevan sahalaitakuvion mukaisesti siirryttäessä pohjoisesta etelään, koska aikarajoitteet muuntelevat samalla tavalla. Tämä teoria perustunee epärealistisiin oletuksiin, koska kokeelliset tulokset eivät tukeneet teoriaa silloinkaan, kun mittariperhosten ruumiinkoko muunteli ennustetulla tavalla. Teoreettinen tutkimus osoitti, että myös lisääntymispanostuksen tulisi muunnella sahalaitakuvion mukaisesti suhteessa kesän pituuteen siten, että se on korkeimmillaan siellä, missä aikarajoitteet ovat tiukat. Mittariperhosten tutkiminen antoi jossain määrin tukea tälle ennusteelle. Tulosten perusteella jatkuvaa maantieteellistä muuntelua ennustetaan elinkierto-ominaisuuksille, jotka muuntelevat jatkuvalla asteikolla. Erilaiset elinkiertostrategiat voivat sen sijaan säilyä populaatiossa, jos elinkierto-ominaisuuksien muuntelu on diskreettiä. Eri ominaisuuksien monimutkaiset vuorovaikutukset sekä eri sukupolvien mahdollisesti kokemat erilaiset aikarajoitteet olisi syytä tuntea, kun tarkastelun kohteena on yksittäisen ominaisuuden evoluutio

La sélection de la parentèle est le concept actuellement le plus fréquemment avancé pour justifier l’évolution et le maintien d'une caste ouvrière stérile chez les Hyménoptères sociaux. La fourmi méditerranéenne Cataglyphis cursor possède plusieurs traits biologiques qui font de cette espèce un modèle particulièrement intéressant pour tester les prédictions de la théorie de la sélection de la parentèle, le plus important d'entre eux étant la capacité des ouvrières, qui ne s'accouplent jamais, à produire une descendance mâle (haploïde) par parthénogenèse arrhénotoque, ou femelle (diploïde) par parthénogenèse thélytoque. Nos analyses génétiques, basées sur des marqueurs microsatellites développés au préalable pour cette espèce, ont révélé que les reines utilisent la reproduction sexuée et asexuée respectivement pour la production de la caste ouvrière et reproductrice. L'analyse du pedigree des reproductrices issues de la reproduction asexuée nous a permis d'identifier le mécanisme cytologique de la parthénogenèse thélytoque et d'estimer la proportion de reines issues de la reproduction des ouvrières au sein de la population. De plus, bien que les reines soient capables de produire une descendance diploïde (femelle) par parthénogenèse thélytoque, elles ont conservé la reproduction sexuée pour la caste ouvrière et s'accouplent avec plusieurs mâles. Ceci indique que la reproduction sexuée a une fonction importante au niveau de la colonie, et nous avons testé certaines des hypothèses avancées pour justifier l'évolution de la polyandrie. Finalement, nous avons étudié l'impact des stratégies de dispersion de cette espèce sur le sex-ratio de la descendance sexuée. Ces résultats confirment l'intérêt que représente l'étude des stratégies reproductrices chez les Hyménoptères sociaux pour tester les prédiction de diverses théories en biologie évolutives et ouvrent également de nouvelles perspectives de recherche, tant chez C. cursor que chez d'autres espèces appartenant au genre Cataglyphis.
Kin selection is, to date, the most widely accepted theory to justify the evolution of a sterile worker caste among social Hymenoptera. The Mediterranean ant Cataglyphis cursor represents an interesting biological model for several reasons, the most important of them being the ability for unmated workers to produce haploid (male) offspring, through arrhenotokous parthenogenesis, and diploid (female) offspring, through thelytokous parthenogenesis. Our genetic analyses, based on microsatellite loci developed for this purpose, revealed that queens selectively use sexual and asexual reproduction to produce workers and sexuals, respectively. Pedigree analyses allowed us to identify the cytological mechanism involved in thelytokous parthenogenesis and to estimate the proportion of worker-produced queens in the study population. Although C. cursor queens do not require mating to produce diploid offspring, they have retained sexual reproduction and mate multiply with up to 8 males. This suggests that sexual reproduction has important benefits for colony function, and we tested several hypotheses accounting for the evolution of polyandry. Eventually, we studied the effect of dispersal strategies on sex-ratio of the sexual brood. These results confirm the interest of investigating the reproductive strategies of social Hymenoptera to test the predictions of diverse theories in the field of evolutionary biology, and open new research perspectives in C. cursor and other ants of the Cataglyphis genera.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

This thesis presents two studies where natural and sexual selection have interacted to evolve sexual behaviours. The thesis uses mathematical modelling to understand how these forces have caused each behaviour to evolve. This is useful because the results allow for reflection on the potential role of sexual selection in adaptation of these species to a changing environment. The first study is of early male arrival to spring breeding grounds in migratory avian species, this is termed protandry. The study explores the main hypotheses for avian protandry and then tests the susceptibility of each hypothesis to changing environment. The second study is of convenience polyandry in species where there is conflict over mating rate. Females have multiple strategies to avoid harassive males but strategies vary in cost and success rate; she must balance her strategy use to minimise her fitness depreciation. The study identifies the main factors that cause convenience polyandry to evolve and paves the way for future studies to investigate if sexual selection over resistance strategy provides these species a future advantage in adaptation to a changing environment.

Estudos relacionados ao sistema de acasalamento nos insetos permite a compreensão dos aspectos evolutivos do comportamento reprodutivo de uma espécie. Esses sistemas são classificados, geralmente, pelo número de parceiros sexuais de um indivíduo durante um período de acasalamento. Em fêmeas, pode ocorrer monogamia, quando a cópula for realizada com somente um macho e, poliandria, quando há ocorrência de múltiplas cópulas com machos diferentes ou com o mesmo macho (cópulas repetidas). Em espécies como a broca-do-café, Hypothenemus hampei, que passam a maior parte de sua vida (ovo a adulto) no interior do fruto de café e possuem ciclo multivoltino os estudos envolvendo o sistema de acasalamento são escassos. Portanto, este trabalho visou estudar o acasalamento da broca-do-café, avaliando se há ocorrência de poliandria e os possíveis efeitos de múltiplas cópulas e cópulas repetidas sobre a bioecologia da fêmea e sua prole. Os resultados revelaram pela primeira vez a ocorrência de poliandria em H. hampei. Foi observado um maior número de recópulas em fêmeas colonizadoras, quando comparado com as fêmeas em oviposição, sugerindo que a condição fisiológica da fêmea foi um fator decisivo no momento da recópula. Além disso, a duração da recópula foi menor nas fêmeas em oviposição do que em fêmeas colonizadoras. A fecundidade foi afetada negativamente pela poliandria, sugerindo a presença de um custo associado a realização de múltiplas cópulas. A longevidade não foi influenciada pelo sistema de acasalamento, demonstrando que a poliandria não influenciou o tempo de vida das fêmeas. A recuperação larva:adulto em H. hampei não foi influenciada pelo sistema de acasalamento. Por outro lado, a taxa de eclosão de larvas foi superior na condição de poliandria, comparativamente à monogamia.
Researches about insects mating systems are important to understand the aspects of reproductive behavior evolution. Mating systems are usually grouped according to the number of mates during mating. Insect females mating system are classified as monogamy when there is only one copulation per male while polyandry refers to multiple mating with different males or with the same male (repeated mating). There is a lack of researches dealing with mating systems in species like the coffee berry borer, Hypothenemus hampei, which spend most of its life cycle (egg to adult) inside of the coffee berry and has a multivoltine cycle. This research aimed to study the mating system of H. hampei females, verifying the existence of polyandry and evaluating the effects of the multiple and repeated mating on the bioecology of the female and its offspring. The current study showed for the first time the occurrence of polyandry on females of H. hampei. The number of remating in colonizing females was higher than in the females under oviposition, thus the female physiological condition is crucial on remating behavior. The copula duration was shorter in females under oviposition than in the colonizing females. Fecundity was negatively affected by polyandry suggesting the existence of costs associated with multiple mating by females. Longevity were not influenced by the mating systems, showing that polyandry does not affect female lifetime. Although egg hatching was superior in polyandry compared to monogamy, the larva:adult recovery rate in H. hampei was not affected by the mating system.

Cette thèse porte sur deux espèces de grands requins, le requin bouledogue Carcharhinus leucas et le requin tigre Galeocerdo cuvier. Les objectifs sont d'étudier la structure génétique de leurs populations, la taille efficace des populations identifiées et les modes de reproduction de ces deux espèces. Une différenciation génétique importante a été identifiée entre les populations de requin bouledogue de l'Ouest de l'océan Indien et de l'Ouest du Pacifique, reflétant soit une absence de flux de gènes contemporains, soit des flux de gènes uniquement assurés par les mâles. À l'inverse, les populations de requin tigre de ces deux régions sont homogènes génétiquement. Une plus faible diversité génétique a été identifiée chez le requin tigre que chez le requin bouledogue, peut-être liée à une diminution forte des effectifs datant de moins de 3 000 ans. Autour de La Réunion, les populations des requins bouledogue et tigre suivent des dynamiques différentes, liées à leurs modes de reproduction. Chez le requin bouledogue, les individus semblent fidèles à des zones côtières particulières (philopatrie) pour s'accoupler et/ou mettre bas, et les portées sont fréquemment issues de plusieurs pères (polyandrie). À l'inverse, les zones d'accouplement et de mise bas du requin tigre restent mal connues, et cette espèce semble exclusivement monoandre, caractéristiques liées à sa nature semi-océanique. Ces travaux montrent les capacités de dispersion importantes de ces deux espèces. Leurs populations présentent des dynamiques différentes induisant une vulnérabilité différente aux pressions anthropiques
This PhD thesis focuses on two large shark species, the bull shark Carcharhinus leucas and the tiger shark Galeocerdo cuvier. The aims are to study the genetic structuring of their populations, the effective population size of the delimited populations and the reproductive modes of both species. A strong genetic differentiation was highlighted between bull shark populations from the Western Indian Ocean and the Western Pacific, due to either an absence of contemporary gene flow or to an absence of female gene flow only. On the opposite, tiger shark populations seem genetically homogenous, with important genetic connectivity between both regions. Within each region, no genetic differentiation among localities was highlighted for both species. A weaker genetic diversity was identified for the tiger shark, probably linked to the occurrence of a recent bottleneck occurring less than 3,000 years ago. Around Reunion Island, bull and tiger shark populations present different dynamics, linked to their reproductive modes. Bull shark individuals from both sexes seem to exhibit some fidelity to specific coastal sites (philopatry) to mate and/or deliver embryos, and litters are frequently issued from several fathers (polyandry). On the opposite, mating and pupping areas of the tiger shark remain poorly known, and this species seems exclusively monoandrous, probably linked to its semi-oceanic nature.This work highlights the high dispersal abilities of both species. Their populations present different dynamics, leading to different sensitivities to anthropogenic pressures. These results point out the need to adopt management plans specific to each species

Les insectes sociaux représentent le paradigme de la vie coopérative dans le règne animal. Ceci repose sur l’existence d’une division des activités reproductrices entre des individus reproducteurs (les reines et les mâles) et une majorité d’ouvrières sacrifiant leurs propres potentialités reproductives pour assurer l’essentiel des tâches logistiques nécessaires à l’essor des sociétés. Chez les Hyménoptères sociaux, l’analyse comparative des stratégies de reproduction révèle que la structure monogyne (une reine par société) et monandre (un seul accouplement par reine) est l’état ancestral des sociétés. Cette structure favorise une corrélation génétique élevée entre les ouvrières et le couvain qu’elles élèvent et, par conséquent, leur succès reproductif global (inclusive fitness). Cependant, un nombre croissant d’études génétiques montre que la structure des sociétés peut fortement s’éloigner de ce pattern. Ceci est particulièrement manifeste chez les fourmis, lesquelles présentent un très large polymorphisme social se traduisant par une grande variabilité du nombre de femelles reproductrices au sein des sociétés. Les formicidés sont également remarquables par la diversité de leurs modes de reproduction. Cette diversité concerne la fréquence des accouplements (monandrie/polyandrie) ou encore l’exploitation conditionnelle des modes de reproductions sexuée et asexuée. Chez quelques espèces, les futures reines sont en effet produites par parthénogenèse (elles sont des quasi-clones de leur mère), alors que les ouvrières sont issues d'une reproduction sexuée classique. Cette stratégie exceptionnelle permet aux reines d'accroître le taux de transmission de copies de leurs gènes dans la descendance, tout en conservant les bénéfices d'une diversité génétique dans la force ouvrière. Cette grande diversité de structures sociales et de modes de reproduction suggère l’action de nombreuses pressions sélectives. Les travaux réalisés dans le cadre de cette thèse de doctorat visent à déterminer les facteurs responsables du large polymorphisme social et des nombreux modes de reproduction observés chez les fourmis désertiques du genre Cataglyphis. Ils sont articulés autour de deux axes principaux.

Les analyses phylogénétiques montrent que la polyandrie est ancestrale au sein du genre Cataglyphis. Le premier axe de ce travail a pour but d’étudier les causes évolutives justifiant le maintien d’un tel système de reproduction au sein de ce genre. Ce travail porte sur les avantages d’une diversité génétique accrue parmi les ouvrières. Une telle diversité génétique permettrait notamment d'accroître le polymorphisme de taille des ouvrières et l'efficacité de la division du travail [Chapitre 1], ou la résistance aux pathogènes de la force ouvrière [Chapitre 2]. [1] Ce premier travail a été réalisé sur Cataglyphis cursor, une espèce strictement monogyne et polyandre. Les résultats de cette étude révèlent une très grande fidélité des ouvrières à la tâche. Ils montrent l’existence d’une association significative entre la tâche réalisée par une ouvrière et sa lignée paternelle, ainsi qu’entre la taille des ouvrières et la tâche effectuée. [2] Le second travail de cette thèse a été réalisé chez C. mauritanica. Nos résultats montrent que la résistance aux pathogènes diffère entre ouvrières issues de différentes lignées paternelles lorsque ces dernières sont isolées. Curieusement, cette différence s’estompe lorsque les lignées paternelles sont regroupées au sein des sociétés polyandres. Dès lors, la polyandrie permettrait d’homogénéiser l’immunité des sociétés. Nos données montrent cependant que la résistance des ouvrières à Metarhizium anisopliae n’est pas corrélée à la diversité génétique de la colonie ou au nombre d’accouplements des reines.

Le second axe de ce travail porte sur les stratégies de reproduction remarquables observées chez les espèces de Cataglyphis appartenant au groupe altisquamis :C. velox, C. mauritanica, C. humeya et C. hispanica. Ces espèces partagent une stratégie unique dans le règne animal, appelée hybridogénèse sociale. L’hybridogénèse classique est un système reproductif dans lequel les parents issus de lignées génétiques distinctes s’hybrident. Alors que les génomes maternels et paternels sont exprimés dans la lignée somatique des descendants, le génome paternel est systématiquement écarté de la lignée germinale. En conséquence, seul le génome maternel est transmis aux générations futures. Dans le schéma d’hybridogénèse sociale reporté dans ces travaux, les reines s’accouplent systématiquement avec un mâle originaire d’une lignée génétique distincte. Elles utilisent la reproduction sexuée pour la production d’une caste ouvrière stérile intégralement hybride (analogue à la lignée somatique) et la reproduction asexuée par parthénogénèse pour la production des castes reproductrices mâles et femelles (analogues à la lignée germinale). Dans ce système, bien que les génomes paternels et maternels soient exprimés dans la caste ouvrière, seul le génome maternel est transmis aux descendants reproducteurs [Chapitre 3]. Le groupe altisquamis est représenté par plusieurs espèces au sein desquelles deux lignées génétiques s’hybrident systématiquement pour la production de la caste ouvrière. Le dernier chapitre de cette thèse [4] est une analyse phylogéographique des espèces de ce groupe dans la péninsule ibérique. Les résultats confirment l’existence d’une seule paire de lignées génétiques au sein de chaque espèce. Ces résultats révèlent également une contradiction entre les marqueurs nucléaires et mitochondriaux traduisant la complexité du système reproductif. Ces travaux soulignent l’ambiguïté des relations phylogéniques entre espèces d’un tel système et discutent de son implication dans la spéciation des espèces hybridogénétiques.

Social insects represent the most extreme form of cooperative life in the animal kingdom. This is based on the existence of a division of reproductive activities between the reproductive individuals (queens and males) and a majority of workers performing all logistical tasks at the expense of their own reproduction. In social Hymenoptera, comparative analysis of reproductive strategies reveals that colonies headed by a single mated queen (monogyny/monoandry) is the ancestral structure of colonies. This structure provides a high genetic correlation between the workers and the brood they raise and, therefore, their overall reproductive success (inclusive fitness). However, an increasing number of genetic studies reveal that the reproductive structure of colonies can strongly differ from this pattern. This is particularly obvious in ants, which have a very large social polymorphism resulting in a large variability in the number of reproductive females within colonies. The Formicidae are also remarkable for the diversity of their modes of reproduction. This diversity relates to mating frequency (monoandry/polyandry) or conditional use of sexual and asexual reproduction. In some species, new queens are produced by parthenogenesis (they are almost clones of their mothers), while the workers arise from a classical sexual reproduction. By using alternative modes of reproduction for queen and worker castes, queens can increase the transmission rate of their genes to their reproductive female offspring while maintaining genetic diversity in the worker population. This high diversity of social structures and modes of reproduction suggests the occurrence of many selective forces. This thesis aimed at determining environmental and genetic factors responsible for the large social polymorphism and the high diversity of reproductive modes display by Cataglyphis desert ants. This thesis is divided into two main parts.

Phylogenetic analyses show that polyandry is ancestral across the genus Cataglyphis. The first part of this thesis examines the genetic hypothesis to account for the evolution and maintenance of multiple mating by queen in this genus. This work focuses on the benefits of increased genetic diversity among workers. Such genetic diversity may increase the size polymorphism of the worker force and improve efficiency of the division of labor [Chapter 1] or increase pathogen resistance of the colony [Chapter 2]. In Chapter 1, the genetic hypothesis to enhance efficiency of division of labor was tested on Cataglyphis cursor, a strictly monogynous and polyandrous species. The results reveal a great fidelity in task performance by workers. They reveal a significant association between patriline and task preference: workers belonging to different patrilines differ in their propensity to perform a given task. We also found that worker size is closely associated with task specialization. The second work of this thesis [Chapter 2] was performed in C. mauritanica. Our results show that resistance to pathogens differs between workers from different patrilines when patrilines are raised separately. Surprisingly, this difference disappears when the patrilines are grouped within polyandrous colonies. Therefore, polyandry would standardize the overall resistance of colonies. Consistent with this result, our data show a positive association between the number of matings by the queens and colony resistance to Metarhizium anisopliae.

The second part of this thesis expounds the unorthodox reproductive strategies observed in species belonging to the group Cataglyphis altisquamis: C. velox, C. mauritanica, C. hispanica and C. humeya. These species share a unique strategy in the animal kingdom, called social hybridogenesis. Hybridogenesis is a sexual reproductive system, whereby parents from different genetic origin hybridize. Both the maternal and paternal genomes are expressed in somatic tissues, but the paternal genome is systematically excluded from the germ line, which is therefore purely maternal. Consequently, only the maternal genome spread across generations. Here, we report a unique case of hybridogenesis at a social level. Queens mate exclusively with males originating from a different genetic lineage than their own to produce hybrid workers, while they use parthenogenesis to produce the male and female reproductive castes. In consequences, all sterile workers (somatic line) are sexually produced hybridogens, whereas sexual forms (germ line) are clonally produced. Thus, only maternal genes are perpetuated across generations [Chapter 3]. The group C. altisquamis is represented by several hybridogenetic species in which two highly divergent genetic lineages co-occur, despite their constant hybridization. The last chapter of this thesis [Chapter 4] is a phylogeographic analysis of C. altisquamis species in the Iberian Peninsula. Our results confirm the existence of a single pair of genetic lineages within each species. Our results also reveal strong incongruences between nuclear and mitochondrial markers that reflect the reproductive system complexities. These studies reveal phylogenetic ambiguities among these hybridogenetic species and discuss the involvement of such unconventional system in speciation process.

Doctorat en Sciences
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Gaining a good understanding of marine turtle mating systems is fundamental for their effective conservation, yet there are distinct gaps in our knowledge of their breeding ecology and life history, owing largely to the difficulty in observing these highly mobile animals at sea. Whilst multiple mating by females, or polyandry, has been documented in all marine turtle species, the fitness consequences of this behaviour have not been fully investigated. Furthermore, male mating patterns, operational sex ratios and the number of males contributing to breeding populations are poorly understood, impeding accurate assessments of population viability. In this thesis, I use molecular-based parentage analysis to study, in detail, the genetic mating system of two green turtle (Chelonia mydas) populations. In the focal population in northern Cyprus, I show that, despite exhibiting a strongly female-biased hatchling sex ratio and contrary to our expectations, there are at least 1.3 breeding males to every nesting female. I go on to assess the breeding frequency of male turtles in the population and determine that males do not breed annually at this site, demonstrating that the observed relatively equal sex ratio of breeders is not the result of a few males mating every year, but that the number of breeding males in the population is greater than expected. I show that 24% of nesting females in the population produce clutches with multiple paternity, but do not detect any fitness benefits to polyandrous females, and discuss the potential role of sexual conflict in influencing female mating decisions. Finally, I reveal a high frequency of multiple paternity in green turtle clutches on Ascension Island, one of the largest green turtle rookeries in the world, and discuss possible causes of variation in the level of polyandry among marine turtle populations. The results presented here shed new light on aspects of marine turtle mating systems that are challenging to study, and illustrate the value of molecular data, not only in describing mating patterns, but in elucidating aspects of life history and behaviour that would otherwise be very difficult to ascertain.

In this dissertation, I report new information that is necessary for future mating system studies in a little studied species, the marbled salamander (Ambystoma opacum). I studied female mating behavior, sexual selection, and the consequences of polyandry for individual females and salamander populations. I also compared the performance of several statistical approaches for analyzing genetic mating system data. The first chapter summarizes the characteristics of several novel microsatellite DNA loci as well as cross-amplified loci for marbled salamanders and mole salamanders that may be used for future studies. In the second chapter, I report estimates of sire number for 13 marbled salamander clutches based on microsatellite data from 32 hatchlings per clutch. Females mated with as many as three different males as indicated by conservative techniques. Less than half of females mated with multiple males. Based on comparative analyses, I recommend the parental reconstruction approach with the computer program GERUD for assessing multiple paternity. The third chapter describes an experiment designed to study sexual selection. As expected, in breeding mesocosms, the potential for sexual selection was much higher for males than for females. Size was unrelated to variance in male reproductive fitness. Only opportunity for selection and Morisita’s index conformed to theoretical expectations of the relationship between operational sex ratio and the potential for sexual selection among males. Because opportunity for selection has intuitive links to formal sexual selection theory, I recommend its continued use. In the fourth chapter, I compared polyandrous and monandrous females to explore the potential fitness consequences of multimale mating. No fitness measure at the egg or hatchling stage (clutch size, hatching success, hatchling size, etc.) differed between the two types of clutches. Size of metamorphs was not different, but polyandrous clutches had significantly higher survival to metamorphosis. In the fifth chapter, I analyzed effects of increased polyandry and male availability on genetic diversity, effective population size (Ne), and fitness of experimental populations. Although no analyses were significant, some effects were moderate to high in size. Ne was higher when estimated from hatchlings than with metamorphs.

A key feature of social Hymenoptera is the division of labor in reproduction between one or a few fertile individuals – the queen(s) – and many sterile nestmates that function as helpers – the workers. The reproductive altruism of workers has long been considered as one of the most important paradox of Evolution. Today, kin selection (Hamilton 1964a,b) is recognized as a prime selective force for the evolution reproductive altruism in Hymenoptera. Hamilton’s kin selection theory states that workers may benefit helping relatives reproduce as long as the relatives they aid share a higher than average proportion of their genes with the workers and effectively pass on copies of the workers' genes to the next generation. Relatedness between colony members is therefore pivotal in kin selection theory, because it directly influences the benefits from indirect fitness. In social Hymenoptera, within-colony relatedness is usually high, because of the haplodiploid sex determinism system. However, several factors of the breeding system are known to affect the colony genetic structure and, hence, the workers’ indirect inclusive fitness: the number of breeders, their genetic relationships and their relative contribution to the reproduction. On the other hand, dispersal strategies influence the population genetic structure, which in turn may result in different interaction patterns between members from neighboring colonies. Despite its central role in the evolution of cooperation and reproductive altruism in animals, kin selection also predicts conflicts between colony members. Because the individuals from a colony are not genetically identical, their reproductive interests may be different (Trivers 1974). These conflicts are diversified, both regarding their actors and their causes (Trivers & Hare 1976; Bourke & Franks 1995; Keller 1995; Chapuisat & Keller 1999b; Keller & Reeve 1999; Sundström & Boomsma 2001). The first part of this work deals with the population genetic structure, mating system and dispersal strategies of two Pheidole ants, the Mediterranean ant Pheidole pallidula and the Mojave Desert ant Pheidole tucsonica. Chapter 1 investigates the population genetic structure, the breeding system, the colony kin composition and the colony genetic structure of the Mediterranean ant P. pallidula. This study was performed by using highly polymorphic DNA microsatellite marker loci. The results show that a single, unrelated male inseminates each queen. Colonies are monogynous (i.e. headed by one reproductive queen) or polygynous (i.e. headed by 2 to 4 functional queens). Moreover, they are genetically differentiated and form a population exhibiting significant isolation-by-distance, suggesting that some colonies originate through budding. Chapter 2 reports cross-species amplifications of microsatellite markers developed for the ant P. pallidula on 13 ant species belonging to the sub-family Myrmicinae. Moreover, levels of genetic diversity within a colony, as well as relationship among colonies are studied for the black ant Pheidole tucsonica. Chapter 3 characterizes the level of inter-nest aggression, the spatial distribution and the genetic structure of a P. tucsonica population. The results show that inter-colony aggression varies from none to “all out” fights and that it is largely non-transitive. No effect of geographical distance or genetic structure on inter-nest aggression levels is detected. Moreover, genetic data reveal high rates of polygyny and/or polyandry. Overall, these results do not support the idea of a simple mechanism of nestmate recognition through queen or worker-produced pheromones or environmental cues. The second part of this work is devoted to the queen-queen conflict over reproduction, and the queen-workers conflict over sex allocation in P. pallidula. Chapter 4 is a detailed analysis on the partitioning of reproduction among queens in polygynous colonies of the species. Our results show a significant departure from equal contribution of queens to reproductive female, male and worker production. Reproductive skew is greater for male production than for queen and worker production. There is no relationship between the magnitude of the reproductive skew and (i) the number of reproductive queens per colony, (ii) their relatedness and (iii) the overall colony productivity, some of the factors predicted to influence the extent of reproductive skew. Finally, this study reveals a trade-off in the relative contribution of nestmate queens to reproductive female and worker production. The queens contributing more to reproductive female production contribute significantly less to worker production. To our knowledge, such a trade-off is shown for the first time in the Formicidae. Chapter 5 focuses on queen-workers conflict over sex allocation. Colonies of the Mediterranean ant P. pallidula show a strong split sex ratio, with 85% colonies producing more than 80% sexuals of one sex. Genetic analyses reveal that this species has an unusual breeding system, with colonies being headed by a single or a few unrelated queens. As expected in such a breeding system, our results show no variation in relatedness asymmetry between monogynous (single queen per colony) and polygynous colonies. Nevertheless, sex allocation is tightly associated with the breeding structure, with monogynous colonies producing a male-biased brood and polygynous colonies almost only females. In addition, sex allocation is closely correlated with colony total sexual productivity. Overall, our data show that when colonies become more productive (and presumably larger) they shift from monogyny to polygyny and from male production to female production, a pattern that has never been reported in social insects so far. A new explanation based on the concept of the “tragedy of the commons” is proposed to explain the strong sex ratio specialization observed in P. pallidula and in other species characterized by facultative polygyny. Chapter 6 investigates the relationship between the breeding system (monogynous vs. polygynous colonies) and the biosynthesis rate of juvenile hormone. Previous works in P. pallidula showed (i) that maternal effects induced by hormones and/or other compounds transferred to the eggs could influence the caste fate of female eggs and (ii) that sex specialization is tightly associated with the breeding structure (monogynous colonies produce a male-biased brood and polygynous colonies almost only females - Chapter 5). This study reveals a strong relationship between the biosynthetic rate of juvenile hormone (JH) production and the breeding system. Because in this species the breeding structure is closely associated with colony sex ratio, we propose that the rate of JH in queens could be a critical parameter in colony sex ratio determination. Queens of P. pallidula would exert partial control over sex ratio by laying different proportions of worker-destined eggs and queen-destined eggs according to the structure monogynous or polygynous of their colony. To conclude, some perspectives for future research on the different topics presented in this work are suggested.
Doctorat en Sciences
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Given multiple matings from females, sexual selection continues after insemination in the form of postcopulatory sexual selection. This process is formed by two main mechanisms: sperm competition (competition of sperm of two or more males for the fertilization of the eggs of the same female) and cryptic female choice. These act as powerful selective pressures for the evolution of reproductive biology of both males and females. The aim of this thesis is to analyze the relative importance of sperm competition and cryptic female choice in determining a male reproductive success. The study species is the guppy (Poecilia reticulata), a freshwater fish, ovoviviparous with internal fertilization. Using artificial insemination, I studied if females can obtain fecundity benefits from mating with colourful males (as predicted by Sheldon's Phenotype-linked fertility hypothesis), the role of sperm number and sperm quality for sperm competition success, repeatability of a male's fertilization success and the role of MHC genes in non directional cryptic female choice. This technique allows to control for many potential confounding variables, as order of mating, number of sperm inseminated and cryptic female choice. From the experiments, it emerges that directional processes in this species are more important for fertilization success rather than non directional processes, even if a part of variance in fertilization success is explained by a male's similarity for MHC genotype with the female.

Selon la théorie de la sélection de la parentèle, les individus peuvent transmettre des copies de leurs gènes à la génération suivante sans accéder eux-mêmes à la reproduction, mais en aidant des apparentés à augmenter leur propre succès reproductif. Ce concept reste aujourd'hui l'explication la plus probable pour justifier l'évolution de l’altruisme de reproduction dans le règne animal. Les coefficients de corrélations génétiques entre les membres d’un groupe ont une importance capitale, puisqu'ils influencent directement les bénéfices génétiques indirects associés au comportement altruiste. Trois principaux facteurs sont cependant connus pour influencer profondément l'architecture des sociétés: (i) le nombre de reines présentes dans un nid (polygynie), (ii) le nombre d'accouplements des reines (polyandrie), et (iii) l’accouplement entre apparentés (consanguinité).

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Doctorat en Sciences
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The family Euphorbiaceae is the sixth largest family of plants in the world represented by 300 genera and 8000 species. Among the many genres that make up this family, the genus Croton stands as the second largest, with about 1300 species, having a neotropical distribution. This genus has been the most studied, due in large part to the chemical compounds produced by this promising group. To contribute to the chemotaxonomic study of the genus Croton and family Euphorbiaceae, the extract of C. polyandrus was subjected to a phytochemical study to isolate chemical constituents through usual chromatographic methods, and then to identify them by means of spectroscopic methods, such as IR, 1H-NMR and 13C and uni-dimensional, spectometryc such as spectrometry mass, and compared with literature data. The chemical study of the aerial parts and roots of C. polyandrus resulted in the identification of nine substances: oxide β-caryophyllene (Cp-1), β-sitosterol (Cp-2), sitosterol-3-O-β-D-glucopyranoside (Cp-3); pheophytin A (Cp-4); Carvacrol (Cp-5), 5-β-hydroxy-2-oxo-p-ment-6 (1)-ene (Cp-6), 3-methoxy-4-hydroxy-benzaldehyde (Cp-7), 1,2,3,4-tetrahidroxi-p-mentano (Cp-8); Sucrose (Cp-9), being the nine first reported in this species. The chemical composition of essential oil had thirty-three components, among which p-cymene (12.4%) showed a major compound with. The essential oil of C. polyandrus were tested against strains of gram positive and gram negative strains of Candida, and cancer cell lines. The essential oil of C. polyandrus tested showed no antibacterial activity, however, showed considerable antifungal and cytotoxic to all cell lines only at the highest concentration tested, using the values of TGI, the essential oil was inactive against the tumor cell lines.
A família Euphorbiaceae é a sexta maior família em número de espécies vegetais identificadas no mundo representada por 300 gêneros e 8000 espécies. Dentre os inúmeros gêneros que compõe esta família, o gênero Croton se destaca como o segundo maior, com cerca de 1300 espécies, possuindo uma distribuição neotropical. Esse gênero tem sido um dos mais estudados, em grande parte devido aos compostos químicos produzidos por este grupo. Visando contribuir para o estudo quimiotaxonômico da família Euphorbiaceae e do gênero Croton, o extrato de C. polyandrus foi submetido a um estudo fitoquímico para isolar seus constituintes químicos, através de métodos cromatográficos usuais, e depois para identificá-los por meio de métodos espectroscópicos, tais como Infravermelho, Ressonância Magnética Nuclear de 1H e 13C uni e bidimensionais e espectométricos, como espectometria de massas, além de comparação com dados da literatura. O estudo químico das folhas e raiz de C. polyandrus resultou na identificação de nove substâncias: óxido de β-cariofileno (Cp-1); β-sitosterol (Cp-2); sitosterol-3-O-β-D-glicopiranosídeo (Cp-3); feofitina A (Cp-4); carvacrol (Cp-5); 5-β-hidroxi-2-oxo-p-ment-6(1)-eno (Cp-6); 4-hidroxi-3-metoxi-benzaldeído (Cp-7); 1,2,3,4-tetrahidroxi-p-mentano (Cp-8); sacarose (Cp-9), sendo as nove relatadas pela primeira vez na espécie. A composição química do óleo essencial apresentou trinta e três componentes, dentre os quais, p-cimeno (12.4%), mostrou-se como composto majoritário. O óleo essencial de C. polyandrus foi testado frente cepas de bactérias gram positivas e gram negativas, cepas de fungos do gênero Candida, e linhagens de células tumorais. O óleo essencial de C. polyandrus testado não mostrou qualquer atividade antibacteriana, no entanto, apresentou uma considerável atividade antifúngica e efeito citotóxico para todas as linhagens celulares apenas na maior concentração testada, ao utilizar os valores de TGI, o óleo essencial se mostrou inativo frente as linhagens celulares tumorais.

Cette thèse a eu pour objectif d’étudier les liens entre les patrons de changement de sexe et d’autres traits de vie tels que la polyandrie et la grégarité au sein de deux espèces de gastéropodes protandres (i. E. Réversion sexuelle de mâle vers femelle) du genre Crepidula Chez C. Fornicata, une relation entre la diversité des contributions paternelles et la variabilité d’un trait larvaire a été montré, conférant un potentiel avantage reproductif aux femelles. L’analyse d’une seconde espèce, C. Convexa, combinés à des données de la littérature suggèrent, au sein du genre Crepidula, un lien entre protandrie, polyandrie et grégarité qui pourrait être modulé par le mode de développement de l’espèce. Chez C. Fornicata, la dynamique démographique influence les patrons de changement de sexe. Une éponge perforante Cliona celeta infestant la population étudiée est peu susceptible de moduler la fécondité des femelles et les patrons de changement de sexe. Ces résultats ont permis de mieux comprendre les facteurs individuels et populationnels influençant les modalités de changement de sexe chez une espèce marine protandre

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Cancer, a complex genetic disease is usually the result of a multifactor process which leads to successive gene changes affecting proliferation, differentiation, and cell death. Natural products are widely used in cancer therapy, and they continue to be a promising source for new anticancer agents. Croton polyandrus Spreng., known popularly as croton de tabuleiro is rarely (either in of phytochemical or pharmacological terms) reported in the literature. Recent studies have shown its antifungal activity, but no in vitro antitumor effects for the leaf s essential oil (whose major component is p-cymene), have been reported. The present study aimed to evaluate the essential oil, extracted from the leaves of C. polyandrus (O.E.C.) for in vivo antitumor activity and toxicity. Hemolysis assay with mouse erythrocytes obtained a CH50 value of 141.0 μg/mL, suggesting moderate cytotoxicity for non-tumor cells that are typically affected during cancer therapy. In acute toxicological testing with mice, the estimated LD50 was 447.18 mg/kg. When O.E.C. was acutely administrated, CNS depressive effects were observed as well as reductions in the body weights of the animals with dosages at 250 and 375 mg/kg. Although not displaying in vitro antitumor activity, as also demonstrated for ascites carcinoma cells in the Ehrlich cytotoxicity assay (IC50 = 270.6μg/ml), O.E.C. showed significant in vivo activity, in the same cell line after nine days of treatment with 100 and 150 mg/kg oil, this considering the parameters of volume, weight and tumor cell viability. There was no significant difference between the effect produced by the oil at doses of 100 and 150 mg/kg, and that produced by 5-FU (the standard drug treatment) at 25 mg/kg. There was a significant increase in the percentage of cells found in either late apoptosis or necrosis after nine days of treatment using both doses of oil. While analyzing the distribution of cells during differing phases of the cell cycle, it was observed that O.E.C. induced cycle arrest at the G0/G1 phase, and increased the sub-G1 fraction, suggesting an induction of cell death through apoptosis. There was also an increase in the median survival rate for the animals with transplanted Ehrlich tumor. The toxicological analyzes revealed (after nine days of treatment) reductions in body weight, increased activity of transaminases (AST and ALT), and hematological changes suggestive of anemia. A decrease was seen in the leukocyte and lymphocyte counts, and a thymus index reduction, which together suggest the immunosuppressive effects commonly observed after anticancer therapy. Histopathologic analysis confirmed O.E.C. hepatotoxicity at 150 mg/kg. However, the damage was moderate and reversible, and O.E.C. did not induce an increase in micronucleated erythrocytes, implying non-genotoxicity. The results for O.E.C. indicate antitumor activity in vivo with moderate toxicity, thus suggesting further preclinical study.
O câncer é uma doença genética complexa, geralmente resultado de um processo multifatorial, que ocasiona alterações sucessivas em genes relacionados à proliferação, diferenciação e morte celular. Produtos naturais são amplamente utilizados na terapia do câncer e continuam representando uma fonte promissora para a descoberta de novos agentes antineoplásicos. Croton polyandrus Spreng. é conhecida popularmente como croton de tabuleiro e é pouco relatada na literatura tanto do ponto de vista fitoquímico como farmacológico. Dados recentes mostram que o componente majoritário do óleo essencial das folhas dessa espécie é o p-cimeno, e que o referido óleo apresenta atividade antifúngica, mas não possui efeito antitumoral in vitro. Esse trabalho teve como objetivo avaliar a atividade antitumoral in vivo e toxicidade do óleo essencial das folhas de C. polyandrus (O.E.C.). No ensaio de hemólise em eritrócitos de camundongos foi obtido um valor de CH50 de 141,0 μg/mL, o que sugere moderada citotoxicidade nesse tipo de célula não tumoral, que é comumente afetada na terapia antineoplásica. No ensaio toxicológico agudo em camundongos o valor estimado da DL50 foi 447,18 mg/kg. Após administração aguda do O.E.C. foram observados efeitos depressores do SNC, bem como redução no peso corporal dos animais tratados com 250 e 375 mg/kg do óleo. Apesar de não apresentar atividade antitumoral in vitro, como também demonstrado no ensaio de citotoxicidade em células de carcinoma ascítico de Ehrlich (CI50 = 270,6 μg/mL), O.E.C. mostrou significante atividade in vivo na mesma linhagem celular, após nove dias de tratamento com 100 e 150 mg/kg do óleo, considerando-se os parâmetros volume, peso e viabilidade das células tumorais. Não houve diferença significante entre o efeito produzido pelo óleo nas doses de 100 e 150 mg/kg e àquele produzido pelo 5-FU (droga padrão) - 25 mg/kg. Houve um aumento significante na porcentagem de células em apoptose tardia/necrose após o tratamento de nove dias com ambas as doses do óleo. Na análise da distribuição das células nas diferentes fases do ciclo celular, foi observado que O.E.C. induziu parada do ciclo na fase G0/G1 e aumento da fração sub-G1, o que sugere indução de morte celular por apoptose. Observou-se ainda, aumento na média de sobrevida dos animais transplantados com tumor de Ehrlich. As análises toxicológicas indicam que, após nove dias de tratamento com O.E.C. foi observado redução no peso corporal, aumento da atividade das transaminases (AST e ALT) e alterações hematológicas sugestivas de anemia. Ainda, foi observada diminuição na contagem de leucócitos e linfócitos, bem como redução no índice de timo, dados esses que em conjunto sugerem imunossupressão, efeito comumente observado após terapia antineoplásica. A análise histopatológica confirmou o indício de hepatotoxicidade, especialmente para a dose de 150 mg/kg do O.E.C., entretanto, os danos foram considerados moderados e reversíveis. O.E.C. não induziu aumento na quantidade de eritrócitos micronucleados, no ensaio do micronúcleo, o que indica ausência de genotoxicidade. Portanto, é possível inferir que o O.E.C. apresenta atividade antitumoral in vivo com moderada toxicidade, o que não representa um fator limitante para a continuação de seus estudos pré-clínicos.

Chez les patineurs, des processus postcopulatoires sont documentés et un conflit sexuel sur le taux d'accouplement est démontré. Cependant, leurs effets combinés sur le succès reproducteur ont rarement été investigués. Cette étude joint une analyse de filiation génétique à des observations comportementales pour évaluer l'effet des processus pré- et post- copulatoires sur le succès reproducteur de Gerris buenoi. Nos résultats montrent la nature antagoniste des combats précopulatoires et un niveau de résistance optimal intermédiaire pour les femelles. Cependant, le taux d'accouplement n'a eu aucune influence sur le succès reproducteur des deux sexes. Un taux d'accouplement élevé permettant à des processus postcopulatoires de se mettre en place ainsi que plusieurs copulations superflues ont vraisemblablement masqué les effets attendus du taux d'accouplement. Notre étude confirme l'idée que des précisions peuvent être apportées sur les forces de sélection sexuelle en jeu lorsque l'on considère tous les épisodes d'un cycle d'accouplement chez les animaux polygynandres.
In water striders, postcopulatory processes are documented and sexual conflict over mating rate has been shown. However, their combined effect on reproductive success has seldom been investigated. This study combines genetic parentage analyses and behavioral observations to investigate how pre- and postcopulatory processes influence the reproductive success of Gerris buenoi. Our results show the antagonistic nature of precopulatory fights and an optimal resistance level for females. However, mating rate had no effect on the reproductive success of both sexes. A high mating rate allowing postcopulatory processes to take place and many superfluous copulations likely masked the expected effects of mating rate on reproductive success. Our study confirms that insights on sexual selection forces at work are gained from investigating all episodes in the reproduction cycles of polygynandrous animals.

Par le biais d’une analyse du discours des personnages excentriques que nous retrouvons dans deux comédies et dans un roman comique français des décennies 1630-1640, Les Visionnaires (1637) de Jean Desmarets de Saint-Sorlin, Le Menteur (1643) de Pierre Corneille et Polyandre (1648) de Charles Sorel, nous nous intéressons aux liens qu’entretiennent illusion et folie au milieu du XVIIe siècle. Nous examinons plus précisément les procédés discursifs et rhétoriques caractéristiques du discours des personnages de fous comiques de cette période, afin de dégager des tendances révélatrices de la pensée d’une période de transition marquée par les questions de l’illusion et des apparences, mais aussi par celles de la raison, de la vraisemblance et de la juste mesure. Nous adoptons ainsi, en parallèle, une approche anthropologique de la littérature nous permettant d’envisager la parole de l’extravagant à partir des rapports étroits qui liaient les différents savoirs à cette époque.

Les fourmis, comme tous les Hyménoptères, sont caractérisées par un mode de détermination du sexe de type haplodiploïde. Les femelles sont issues d’œufs fertilisés et sont diploïdes alors que les mâles se développent à partir d’œufs non fertilisés par parthénogenèse arrhénotoque, et sont haploïdes. A quelques rares exceptions près, le déterminisme de la caste au sein du sexe femelle est réalisé de manière épigénétique :seules les larves diploïdes les mieux nourries et/ou celles produites après le repos hivernal se développent en femelles sexuées (reines), les autres en femelles non reproductrices (ouvrières). Récemment, plusieurs travaux ont montré que les reines de quelques espèces de fourmis sont capables de maximiser leur succès reproductif en exploitant de manière conditionnelle la reproduction sexuée et asexuée. Alors que les ouvrières sont produites à partir d’œufs fertilisés par reproduction sexuée classique, les jeunes femelles reproductrices sont issues d’œufs diploïdes produits par parthénogenèse thélytoque et sont, par conséquent, génétiquement très similaires à leur mère. L’espèce Cataglyphis cursor est le premier modèle chez lequel cette stratégie reproductrice a été mise en évidence (Pearcy et al. 2004b). Les sociétés de C. cursor sont strictement monogynes, les reines sont hautement polyandres et utilisent la reproduction sexuée et asexuée pour la production d’ouvrières et de femelles reproductrices, respectivement. La combinaison de la polyandrie et de la reproduction thélytoque permet aux reines de C. cursor d’optimiser le taux de transmission de leurs gènes via des filles reproductrices, tout en assurant une diversité génétique maximale au sein de la force ouvrière. Par ailleurs, les ouvrières de C. cursor ont conservé leurs ovaires et se reproduisent en l’absence de reine. Elles produisent alors des mâles (par parthénogenèse arrhénotoque), des femelles sexuées et des ouvrières (par parthénogenèse thélytoque) (Cagniant, 1973)

Les travaux réalisés dans le cadre de cette thèse de doctorat visent à déterminer si les stratégies reproductrices remarquables exploitées par C. cursor sont propres à l’espèce ou si elles ont évolué au sein de plusieurs espèces du genre. A cette fin, nos recherches s'articulent autour de 2 axes complémentaires. Premièrement, nous avons approfondi l'étude des stratégies reproductrices chez C. cursor en nous concentrant sur deux aspects. (i) Plusieurs hypothèses ont été proposées pour justifier l’évolution de la polyandrie chez les fourmis. Nos travaux ont testé et éliminé trois d’entre elles pour C. cursor :l’hypothèse de la limitation spermatique, celle des coûts des mâles diploïdes et celle selon laquelle une plus grande variabilité génétique des ouvrières améliorerait la division du travail. (ii) Nous avons mis en évidence l’existence d’un contrôle des reines dans le déterminisme de la caste chez cette espèce. Les reines ne produisent des œufs thélytoques qu’au début du printemps, lorsque les ouvrières élèvent les œufs en sexués. Plus tard dans la saison, les reines ne produisent plus que des œufs fertilisés qui se développeront en ouvrières.

Deuxièmement, à titre comparatif, nous avons analysé la structure socio-génétique de deux autres espèces de Cataglyphis :C. sabulosa et C. livida. Ces deux espèces sont monogynes et polyandres. Leurs ouvrières sont capables de pondre des œufs haploïdes mais seules les ouvrières de C. sabulosa ont produits des œufs diploïdes thélytoques. Aucune des reines des deux espèces n’utilisent la parthénogenèse thélytoque pour produire des femelles sexuées.

L’ensemble des résultats obtenus dans notre étude ont été replacés dans une perspective évolutive afin de préciser quand la polygynie, la polyandrie et la thélytoquie seraient apparues dans la phylogénie des Cataglyphis.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

La monogamie est un système d'appariement qui lie une seule femelle à un seul mâle. Cette monogamie peut être définie comme sociale et génétique (au-delà de l'observation du couple, la descendance est seulement issue de ce couple, aucun changement de partenaire n'apparaît), ou comme sociale et non génétique (dans ce cas, des infidélités ou des divorces peuvent être observés). Ce système d'appariement est très rare dans le monde animal. Il concerne moins de 1% des animaux et la majeure partie des études sur le monogamie a été réalisée sur des vertébrés (notamment sur les oiseaux dont 90% des espèces présentent ce système monogame). Plus rares sont les études réalisées sur les invertébrés (quelques cas de monogamie étudiée chez des crustacés, des insectes ...). Pourtant l'étude de la monogamie à un niveau taxonomique inférieur permet de comprendre ses caractéristiques en éliminant la complexité sociale (apprentissage, imitation ...) présente chez les vertébrés. Schistosoma mansoni est un parasite (responsable de la bilharziose) qui présente plusieurs aspects intéressants du point de vue système d'appariement : (1) la femelle vit dans le canal gynéchophore de son mâle, nous observons bien un couple formé d'une seule femelle et d'un seul mâle, il s'agit donc d'une monogamie sociale ; (2) S. mansoni est l'espèce monogame de rang taxonomique le plus bas à notre connaissance, ce qui permet d'éliminer au maximum les biais de complexité sociale cités précédemment ; (3) enfin, cette espèce parasite présente des avantages d'un point de vue expérimental : les sexes et génotypes des individus utilisés peuvent et sont contrôlés en laboratoire et des populations "naturellement" clonales sont à notre disposition. C'est pourquoi, nous nous sommes intéressés à la monogamie chez cet invertébré parasite monogame. Plusieurs questions sont développées durant cette thèse : qui est monogame parmi les Schistosomatidae et pourquoi ? Est-ce que une monogamie sociale et génétique ou sociale et non génétique (i.e. des changements de partenaires sont-ils observés) ? Quels sont les facteurs impliqués dans ces changements de partenaire (dissimilarité entre les partenaires du couple, biais de sex ratio en faveur des males, différences neutres, fonctionnelles et phénotypiques entre les mâles, effet du système immunitaire de l'hôte vertébré) ? C'est par l'association de réflexions et d'expérimentations que nous tentons de répondre à ces questions.

Why do females across a wide range of taxa mate with more than one male? Here, I present the hypothesis that females engage in polyandry as a hedge against genetic incompatibility. I review evidence from the literature showing that the genomes of species are dynamic entities, constantly evolving as a consequence of genetic conflicts within and between the nucleus and the cytoplasm. Cellular endosymbionts, segregation distorter alleles, transposable elements and genomically-imprinted genes can all threaten female fitness by modifying maternal and paternal haplotypes in ways that render them incompatible within the developing embryo. I discuss the potential for polyandrous females to utilize postcopulatory mechanisms such as sperm competition, female choice of sperm, and reallocation of maternal resources from defective to viable embryos in order to minimize the risk and/or cost of fertilization by genetically-incompatible sperm. In a sperm precedence experiment carried out on the pseudoscorpion, Cordylochernes scorpioides, single-locus minisatellite DNA fingerprinting demonstrated strong last-male sperm precedence when females were mated to two males which broke down completely when females were mated to three males. This result indicates that the opportunity for postcopulatory sexual selection may be much greater in nature than is evident from standard, laboratory, two-male mating experiments. Polyandry in this pseudoscorpion is shown to be a deliberate strategy which increases reproductive success. In laboratory experiments, females restricted to mating with a single male experienced a higher rate of embryo failure and produced significantly fewer offspring than either females mated to more than one male in the laboratory or females naturally inseminated in the field. Previously proposed hypotheses such as forced copulation, insufficient sperm from a single mating, male nutrient donations, offspring genetic diversity and inherent male genetic quality cannot explain this higher reproductive success of polyandrous females. Observations of meiotic drive, highly-skewed sex ratios and paternal effects on sex ratio in this pseudoscorpion are consistent with the hypothesis that, by accumulating sperm from several males, C. scorpioides females reduce the number of embryos which fail as a consequence of genetic incompatibility between maternal and paternal genomes.

Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, Discipline of Ecology and Evolutionary Biology, 2008.
"March 2008" -- T.P. Includes author's previously published papers. Bibliography: pages 104-118. Also available in print form.

Tese de doutoramento, Biodiversidade, Genética e Evolução, Universidade de Lisboa, Faculdade de Ciências, 2017
Organisms compete for several resource types, the most studied being food, hosts and mates. Regrettably, the study of competition for each of these resource types belongs to different research fields that rarely overlaps, which might hamper a comprehensive understanding of competition as pervasive selective force. In this work, we begin by showing how experimental evolution can be transversally applied to the study of competition across research fields and attempt to extract general patterns and processes, as in all cases individuals are competing for the use of a limiting resource. The rest of this thesis is directed towards competition for mates, a type of competition that is shaped by sexual selection. The main goal of this work was to study the adaptations favoured by sexual selection at different stages of reproduction, namely prior and after mating, in order to better understand the occurrence of polyandry in species with first male sperm precedence. In these species, the first male that mates with a female will sire all her offspring. Consequently, it seems paradoxical that females mate multiply, except if this behaviour provides an advantage for females or males, if it correlates with other traits, or if it occurs inadvertently. In order to tackle this, we used the spider mite Tetranychus urticae, a haplodiploid species with first male sperm precedence in which polyandry is pervasive. First, we tested whether males distinguish between virgin and mated females and which type of cues they use to exert their preference. In fact, spider mite males preferred virgin over mated females and used chemical cues, namely volatiles and chemical trails, to distinguish them. These results indicate that polyandry does not occur due to a lack of ability to discriminate females of different matings status, suggesting this behaviour might be advantageous for either sex. Consequently, the next step was to test the potential costs and benefits of polyandry for males and females. Neither males, nor females benefited directly with polyandry. In fact, females that mated multiple times survived less and laid fewer eggs, compared to females that mated once or twice only. Nevertheless, males did not suffer longevity costs when they mated with mated females and they were able to decrease the fitness of first males, gaining an indirect benefit with this behaviour. Polyandry can thus be, even if partially, explained by this indirect benefit. Still, these results do not rule out the existence of other, indirect benefits. For instance, by mating multiply, individuals might reduce the risk of only mating with incompatible mates. Incompatible matings may be attributed to the presence of endosymbiotic bacteria. These organisms can employ various tactics, such as altering the reproduction of their hosts, in order to favour their own transmission. When these tactics are costly for the host, hosts are expected to evolve strategies to avoid or reduce such costs. Spider mite populations are often infected with Wolbachia, an endosymbiotic bacterium that induces cytoplasmic incompatibility (CI), whereby crosses between uninfected females and infected males yield reduced fertilized offspring. Here we tested whether T. urticae uninfected females evolve mate choice and multiple mating to circumvent the costs imposed by CI. To this aim, we performed experimental evolution on spider-mite populations with i) full Wolbachia infection, ii) no infection, or iii) mixed infection. In the latter, Wolbachia-uninfected females could copulate with both Wolbachia-infected and Wolbachia-uninfected males at each generation, which is expected to result in high costs for uninfected females, and hence promote the evolution of a compensatory mechanism. Evolving under mixed infection did not affect host mate choice, latency to copulation or copulation duration, after 12 generations of selection. Therefore, the role of Wolbachia in pre-copulatory reproductive isolation in spider mites, if present, is probably residual. However, after 20 generations of selection, uninfected females evolving under mixed infection that mated with Wolbachia-infected males presented a higher degree of CI than those mated first with Wolbachia-infected and then with Wolbachia-uninfected males evolving under mixed infection. Therefore, polyandry can be advantageous when there is the risk of incompatible matings, since it reduces the degree of CI. By doing so, spider mites break their sperm priority pattern in favour of the second male. However, this disruption of sperm precedence only occurred in one direction. Indeed, when the first mating was compatible, i.e., the first male was not infected with Wolbachia, individuals kept first male sperm precedence. The unidirectional disruption of the sperm precedence pattern might be a key factor for the evolution of CI-driven polyandry in species with skewed patterns of sperm precedence. Overall, the results obtained here contribute to improve our understanding of mating strategies by addressing important questions that have been largely neglected so far, namely the putative drivers of multiple mating in species with first male sperm precedence.
Na natureza, os organismos competem por diferentes de tipos de recursos, sendo os recursos mais estudados a comida, os hospedeiros e os parceiros sexuais. Infelizmente, o estudo de cada um destes recursos pertence a uma área de investigação diferente, o que dificulta a compreensão plena do papel da competição enquanto força selectiva. No trabalho que aqui se apresenta, começamos por demonstrar de que modo a evolução experimental pode ser aplicada transversalmente ao estudo da competição, de forma a permitir extrair padrões e processos comuns às várias áreas de investigação. Isto torna-se possível uma vez que, em todos os casos, os organismos competem por acesso a um recurso limitante, qualquer que seja esse recurso. Os capítulos seguintes da tese focam-se na competição por parceiros sexuais, um tipo de competição moldado pela selecção sexual. O principal objectivo deste trabalho foi estudar que adaptações são favorecidas pela selecção sexual em diferentes fases da reprodução, nomeadamente antes e depois do acasalamento. Desta forma, esperamos contribuir para enriquecer o nosso conhecimento no que diz respeito à ocorrência de poliandria, isto é, ao acasalamento de vários machos com uma única fêmea, em espécies com precedência espermática do primeiro macho. Nestas espécies, o primeiro macho a acasalar com uma fêmea é aquele que fertiliza todos os seus ovócitos. Consequentemente, parece paradoxal que estas fêmeas acasalem mais do que uma vez, a não ser que este comportamento traga alguma vantagem, esteja geneticamente relacionado com outra característica que seja vantajosa, ou ocorra inadvertidamente. De modo a poder abordar esta aparente contradição, usámos o ácaro-aranha Tetranychus urticae, uma espécie haplodiplóide, com precedência espermática do primeiro macho e cujos indivíduos acasalam frequentemente com fêmeas já fecundadas. Numa primeira abordagem, testámos se os machos desta espécie eram capazes de distinguir fêmeas virgens de fêmeas fecundadas e que tipo de pistas são usadas pelos machos para exercer a sua preferência. Graças a este estudo, pudemos confirmar que os machos usam pistas químicas, nomeadamente voláteis, e rastos químicos deixados no substrato, para distinguir fêmeas virgens de fêmeas fecundadas. Estes resultados permitiram-nos concluir que a poliandria não ocorre devido a uma incapacidade, por parte dos machos, de discriminar fêmeas fecundadas de fêmeas virgens, o que sugere que este comportamento é vantajoso para pelo menos um dos sexos. Na sequência desta constatação, procurámos encontrar potenciais benefícios provenientes da existência de poliandria em machos e fêmeas. Para esta experiência utilizámos a resistência a um pesticida como marcador genético, o que nos permitiu determinar a paternidade da descendência produzia pelas várias fêmeas testadas. Esta metodologia é essencial para determinar se a poliandria altera o padrão de precedência espermática desta espécie, conferindo assim benefícios directos aos machos. Os nossos resultados indicam que nenhum dos sexos beneficia directamente com acasalamentos múltiplos. De facto, a precedência espermática do primeiro macho foi sempre mantida, independentemente do número e do intervalo entre acasalamentos, sugerindo que acasalar com fêmeas fecundadas não confere nenhum benefício directo aos machos. Para além disso, fêmeas que acasalaram múltiplas vezes apresentaram uma menor longevidade e fecundidade do que fêmeas que acasalaram só uma ou duas vezes, sugerindo que há custos em acasalar múltiplas vezes para as fêmeas. No entanto, os machos desta espécie, apesar de não terem obtido benefícios directos com a poliandria, não sofreram custos de longevidade quando foram colocados exclusivamente com fêmeas previamente fecundadas. Além do mais, o número total de descendência produzida pelo primeiro macho a acasalar com uma fêmea fecundada é menor quando essa fêmea acasala múltiplas vezes, do que quando essa fêmea não acasala novamente, ou acasala apenas mais uma vez. Esta diminuição do número de descendência quando a fêmea acasala múltiplas vezes, faz com que o sucesso reprodutor do primeiro macho diminua, levando a um aumento relativo do sucesso reprodutor dos machos seguintes. Este benefício indirecto pode explicar, ainda que em parte, a ocorrência de poliandria no ácaro-aranha. De qualquer forma, este resultado não exclui a possibilidade de existirem outros benefícios que possam explicar a existência de poliandria. Por exemplo, ao acasalarem múltiplas vezes, os indivíduos podem reduzir o risco de se envolverem apenas em acasalamentos inviáveis. A existência de acasalamentos inviáveis pode ser atribuída à presença de bactérias endosimbiontes. Estes organismos empregam diversas tácticas como, por exemplo, alterar a reprodução dos seus hospedeiros, de forma a favorecerem a sua transmissão. Quando essas tácticas são custosas para o hospedeiro, prevê-se que este evolua estratégias de modo a poder evitar ou reduzir os custos da infecção. Frequentemente, as populações de ácaros encontram-se infectadas com Wolbachia, uma bactéria endossimbiótica que induz incompatibilidade citoplasmática. A incompatibilidade citoplasmática resulta na redução do número de descendência fertilizada proveniente de acasalamentos entre fêmeas não infectadas e machos infectados. Com as experiências seguintes, procurámos saber se fêmeas de ácaros-aranha não infectadas evoluem a capacidade de escolher parceiros sexuais compatíveis ou de acasalar múltiplas vezes, de modo a contornar os custos impostos pela incompatibilidade citoplasmática. De forma a testar esta possibilidade, realizámos uma experiência na qual populações de ácaros-aranha evoluíam nas seguintes condições: i) populações totalmente infectadas com Wolbachia, ii) populações totalmente livres de Wolbachia ou iii) populações com uma prevalência intermédia deste simbionte. No último caso, a cada geração, fêmeas não infectadas foram colocadas com machos infectados e não infectados, na mesma proporção, de modo a promover os acasalamentos entre indivíduos. Este último regime de evolução experimental corresponde às condições ideais para a evolução de um mecanismo compensatório contra a Wolbachia, por parte do hospedeiro. Após doze gerações de selecção, indivíduos mantidos com prevalência intermédia de Wolbachia não alteraram a sua capacidade de escolha. Para além disso, não se verificaram modificações na latência à copula ou na duração de cópula em qualquer um dos regimes. Isto permite-nos concluir que o efeito da Wolbachia na evolução de isolamento reprodutor em ácaros, se existe, é residual. Este resultado é relevante para o estudo da especiação, uma vez que o isolamento reprodutor é considerado um comportamento com elevado impacto neste processo. Apesar de não termos encontrado diferenças no comportamento que antecede a cópula, fêmeas não infectadas que evoluíram em populações com prevalência intermédia de Wolbachia apresentaram uma redução no grau de incompatibilidade citoplasmática após acasalarem com machos infectados e machos não-infectados, sequencialmente. Este resultado permite-nos concluir que a poliandria pode ser vantajosa em ambientes em que existe o risco de acasalamentos inviáveis, uma vez que permite reduzir a incompatibilidade citoplasmática. Ao fazê-lo, os ácaros-aranha alteraram o seu padrão de precedência espermática a favor do segundo macho. No entanto, esta alteração só ocorreu numa direcção, uma vez que, nas situações em que o primeiro macho era compatível, i.e., não estava infectado com Wolbachia, a precedência espermática pelo primeiro macho foi mantida. A unidirecionalidade na alteração do padrão de precedência espermática é muito provavelmente um factor essencial à evolução de poliandria incitada pelos custos associados à incompatibilidade citoplasmática, em espécies com padrões de precedência espermática enviesados. Em suma, o trabalho desenvolvido ao longo desta tese, ao endereçar questões importantes que tinham sido, até agora, negligenciadas, permite-nos compreender mais aprofundadamente qual o papel da poliandria em espécies com precedência espermática do primeiro macho. Para além disso, os resultados apresentados aqui contribuem substancialmente para o estudo das interações entre endosimbiontes e os seus hospedeiros, bem como para compreender de que forma essa interação afecta o processo de especiação.

This thesis examines the reproductive biology of red-tailed phascogales, an obligate male semelparous dasyurid species, which is part of a captive breeding colony at Alice Springs Desert Park. The red-tailed phascogale belongs to a group of dasyurids that shows an unusual reproductive strategy amongst mammals, one which provides opportunity for understanding means by which individuals maximise their reproductive success and the role of sperm competition. The broad aim was to gain an understanding of the reproductive biology of red-tailed phascogales and explore means by which individuals can affect their reproductive success. Examination of the red-tailed phascogale reproductive biology showed that females mated with multiple males and were capable of storing sperm in their oviducts for at least a five day period. Captive female red-tailed phascogales showed greater plasticity in their breeding season than has been observed in Antechinus, which exhibits the same life history strategy. Females were observed to invest heavily into the production of young, producing almost twice as many ova (15.1 ± 1.9) as young they can raise and 76% of females filling six to eight of the eight available teats in a breeding attempt. A 63% male bias was observed in young attaching to the teats, which could be produced through differential attachment of the sexes to teats at birth. Of the 846 young born in the captive breeding colony, 68% were weaned, with weaning occurring between 90-110 days of age and a 53% female bias observed in young being weaned. By weaning, a litter of young weighed 380% of the mothers mass with male young tending to be heavier than females by weaning. No relationship was observed between maternal weight and either litter sex ratio or sex biased growth of young. A positive relationship between maternal body mass and body mass of offspring at weaning was observed, with the body mass of young at weaning correlated with its body mass at maturity. Multiple paternity was observed in more than half of the litters examined, with heavier males having increased siring success compared to lighter males. Genotyping showed that the effective population size for the captive colony was 1.9x that observed from the group managed studbook. Male reproduction was also not as tightly constrained as in Antechinus, with spermatogenic failure not occurring in captive populations until after mating had occurred, meaning males are not reliant on epididymal stores alone for successful breeding. Scrotal diameter showed a positive relationship with testis and epididymal mass across male life, although this relationship was not evident when analysis was restricted to the time of peak sperm production. Captive males showed the opposite pattern of testosterone fluctuations to that observed in wild animals, with lowest levels occurring during the mating period. Captive animals were able to survive up to five years in captivity, in contrast to the obligate semelparity observed in wild males. Although most captive females can survive to breed in a second year and females are known to breed in a second year in the wild, the reproductive strategy of females appears to be aimed at maximising the returns on their first breeding attempt. In males, the need to maximise the investment into the first breeding season is amplified through the complete absence of opportunity to breed again; either through post-mating mortality in the wild or spermatogenic failure in captivity. The results of this study have implications for captive breeding of red-tailed phascogales, with their reproductive biology; spermatogenic failure, restricted breeding season, teat number limiting the number of young raised, high lactational investment into young, sex biases, the need to maintain genetic diversity and biases in siring success; providing challenges for the maintenance of a captive population. The results of this study also provide comparative information that contributes to understanding the unusual life history strategy of Phascogale and Antechinus, and contributes to the growing body of knowledge about mating strategies in marsupials.
Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2008

This thesis examines the reproductive biology of red-tailed phascogales, an obligate male semelparous dasyurid species, which is part of a captive breeding colony at Alice Springs Desert Park. The red-tailed phascogale belongs to a group of dasyurids that shows an unusual reproductive strategy amongst mammals, one which provides opportunity for understanding means by which individuals maximise their reproductive success and the role of sperm competition. The broad aim was to gain an understanding of the reproductive biology of red-tailed phascogales and explore means by which individuals can affect their reproductive success. Examination of the red-tailed phascogale reproductive biology showed that females mated with multiple males and were capable of storing sperm in their oviducts for at least a five day period. Captive female red-tailed phascogales showed greater plasticity in their breeding season than has been observed in Antechinus, which exhibits the same life history strategy. Females were observed to invest heavily into the production of young, producing almost twice as many ova (15.1 ± 1.9) as young they can raise and 76% of females filling six to eight of the eight available teats in a breeding attempt. A 63% male bias was observed in young attaching to the teats, which could be produced through differential attachment of the sexes to teats at birth. Of the 846 young born in the captive breeding colony, 68% were weaned, with weaning occurring between 90-110 days of age and a 53% female bias observed in young being weaned. By weaning, a litter of young weighed 380% of the mothers mass with male young tending to be heavier than females by weaning. No relationship was observed between maternal weight and either litter sex ratio or sex biased growth of young. A positive relationship between maternal body mass and body mass of offspring at weaning was observed, with the body mass of young at weaning correlated with its body mass at maturity. Multiple paternity was observed in more than half of the litters examined, with heavier males having increased siring success compared to lighter males. Genotyping showed that the effective population size for the captive colony was 1.9x that observed from the group managed studbook. Male reproduction was also not as tightly constrained as in Antechinus, with spermatogenic failure not occurring in captive populations until after mating had occurred, meaning males are not reliant on epididymal stores alone for successful breeding. Scrotal diameter showed a positive relationship with testis and epididymal mass across male life, although this relationship was not evident when analysis was restricted to the time of peak sperm production. Captive males showed the opposite pattern of testosterone fluctuations to that observed in wild animals, with lowest levels occurring during the mating period. Captive animals were able to survive up to five years in captivity, in contrast to the obligate semelparity observed in wild males. Although most captive females can survive to breed in a second year and females are known to breed in a second year in the wild, the reproductive strategy of females appears to be aimed at maximising the returns on their first breeding attempt. In males, the need to maximise the investment into the first breeding season is amplified through the complete absence of opportunity to breed again; either through post-mating mortality in the wild or spermatogenic failure in captivity. The results of this study have implications for captive breeding of red-tailed phascogales, with their reproductive biology; spermatogenic failure, restricted breeding season, teat number limiting the number of young raised, high lactational investment into young, sex biases, the need to maintain genetic diversity and biases in siring success; providing challenges for the maintenance of a captive population. The results of this study also provide comparative information that contributes to understanding the unusual life history strategy of Phascogale and Antechinus, and contributes to the growing body of knowledge about mating strategies in marsupials.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1330358
Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2008

Thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of Science.
Breeding was observed in the foam nest frog, Chiromantis xerampelina, over three breeding seasons The mating pattern was characterized by an extended breeding season with a male-biased operational sex ratio and asynchronous and unpredictable female arrival. At more than 90% of nests, from one to seven unpaired males ('peripheral males') gathered around the amplexing pair during nest construction. Those peripheral males closest to the pair competed 'With each other, and with the amplexing male, to position their cloacae against the female's cloaca during oviposition bouts. In a detailed study of a single population, over 80% of males were observed as peripheral males, and 57% of males were observed both in amplexus and as peripheral males. Male mating success and participation at nests was unrelated to size or weight. Chorus participation was the best predictor of male, mating success and participation at nests. The most plausible explanation for the presence of peripheral males was a sperm competition hypothesis; namely that peripheral males compete with the amplexing male for fertilizations by shedding sperm into the nest. I collected data on body mass and testis mass for 13 African anurans. Using additional published data on 19 Japanese anurans, an allometric relationship between body mass and testis mass was calculated. using 16 genera as independent data points. This revealed that C. xerampelina have testes fourteen times heavier than predicted on the basis of body mass. This is consistent with a trend seen in several taxa where testis size is related to the intensity of sperm competition. An additional experiment, in which the arnplexing male was prevented from shedding sperm into the nest, showed that peripheral males are capable of fertilizing eggs. I conclude that peripheral males are engaged in an opportunistic alternative mating tactic involving sperm cosnpetition. More than half the observed females bred polyandrously, some mating with up to three males, This was the result of amplexing males dismounting between nesting sessions, and males displacing one another from amplexus.
Andrew Chakane 2018

Feather ornaments and its role as a signals in sexual selection has been broadly studied topic in avian biology. However, vast majority of studies focus especially on role of male ornamentation and female preferences in sexual selection. Despite this fact, recent work shows, that similar palette of adaptive functions can be found for female feather ornaments, and male preferences for them, respectively. This study focuses on possible importance of female melanin-based ornaments and other individual on breeding performance in the Northern Lapwing (Vanellus vanellus), common polygynous wader breeding in agricultural landscape. No significant predictor of female investment to egg size was found. Long winged females with bigger proportion of secondaries changed during prenuptial moulting and bigger extent of melanin ornaments tended, surprisingly, to later timing of breeding. Contrary to this trend, extent of female ornamentation seems to be sexually selected trait by males. Analysis of male incubation behavior shows, that males incubate more in nests of more ornamented females, as well as in nests in later incubation stage. These findings seems to be in a good agreement with "Differential allocation hypothesis". On the other site, no effect of clutch egg sizes and timing of breeding was found....

The aim of the project was to test female advantages of promiscuous and/or polyandrous mating. Although, previous studies reported improved reproductive success of females copulating with multiple males in many model species, including Eublepharis macularius, this study failed to demonstrate such a benefit of polyandry. Traits reflecting female reproductive success, i.e. the number of produced eggs, egg mass, hatchability, hatchling mass, growth and survival were not influenced by copulation with multiple partners, but some of them were dependent on female condition. Only initial stages of juvenile growth were influenced by female identity and/or investment.

The thesis underpinning this dissertation is based on the Zulu people’s belief in the living-dead and the fact that the latter control the lives of their living descendants. The living descendants use names to express their dissatisfaction with one another. The families perform rituals to appease the living-dead. The living-dead are perceived as guardian angels who are closer to God. They are believed to be able to reward good behavior and reprimand those who are not behaving in an acceptable manner. Names, as Bhengu (1975:52) states, connect people to their living-dead. It is therefore important that this relationship with the living-dead is maintained. Friction is always going to be a problem in polygynous families. Avoiding confrontation is important to people who want to appease their living-dead, who control their lives. Personal names act as a deterrent to angering the living-dead. In a situation where getting even is not an option, opting for a name to voice your disapproval is the easy way out. Names become communication channels between members of the family and the community at large. This study is done from an ethnographic perspective with an attempt to fully describe a variety of aspects of a cultural group to enhance understanding of the people being studied. Spradley (1980:3) states that “The essential core of ethnography is the concern with the meaning of actions and events to the people we seek to understand”. This understanding may be seen as the basis of the method; through ethnographic study, the researcher comes to comprehend, through detailed observation, the existences of peoples and their cultures.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.