Tesis sobre el tema "Polyandry"
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Butchart, Stuart Howard Miles. "Sexual conflicts and polyandry in bronze-winged jacanas". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624987.
Texto completoRonkainen, K. (Katri). "Polyandry, multiple mating and sexual conflict in a water strider, Aquarius paludum". Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526212364.
Texto completoTiivistelmä 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
Nilsson, Tina. "Polyandry and the evolution of reproductive divergence in insects". Doctoral thesis, Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-181.
Texto completoFirman, Renee C. "The evolutionary implications of polyandry in house mice (Mus domesticus)". University of Western Australia. School of Animal Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0162.
Texto completoIvy, Tracie Marie Sakaluk Scott Kitchener. "The evolution of polyandry in the decorated cricket, Gryllodes sigillatus". Normal, Ill. : Illinois State University, 2005. http://proquest.umi.com/pqdweb?index=0&did=1221741601&SrchMode=1&sid=4&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1176386432&clientId=43838.
Texto completoTitle 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.
Herridge, Elizabeth J. "The role of polyandry in sexual selection among dance flies". Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/25013.
Texto completoLong, Christopher. "Testing for indirect benefits of polyandry in the Florida green turtle". Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5982.
Texto completoM.S.
Masters
Biology
Sciences
Biology
Morimoto, Juliano. "Polyandry and nutrition : key modulators of sexual selection in Drosophila melanogaster". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:d0c59fbf-2d31-4959-8001-776a388a5898.
Texto completoWorden, Bradley Dean. "Female mating behavior in the Beetle Tenebrio Molitor : polyandry and parasite-mediated sexual selection /". The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488205318511058.
Texto completoKatvala, M. (Mari). "Female reproduction and conspecific utilisation in an egg-carrying bug:-Who carries, who cares?" Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:9514269691.
Texto completoBanger, Nicola A. "Consequences of Multiple Paternity for Female Fitness in an Ontario Population of Northern Map Turtles, 'Graptemys geographica'". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22881.
Texto completoRossmanith, Eva. "Breeding biology, mating system and population dynamics of the Lesser Spotted Woodepcker (Picoides minor) : combining empirical and model investigations". Phd thesis, Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2005/532/.
Texto completoIn 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.
Neumann, Peter. "The impact of polyandry and drifting on the genotypic composition of honeybee (Apis mellifera L.) colonies". [S.l. : s.n.], 1998. http://deposit.ddb.de/cgi-bin/dokserv?idn=960878742.
Texto completoVälimäki, P. (Panu). "Reproductive tactics in butterflies – the adaptive significance of monandry versus polyandry in Pieris napi". Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514284847.
Texto completoВашека, Тетяна Володимирівна y Валерія Ярославівна Юдіна. "Postmodern moral world: the changes of attitude towards sex and its connections between polyandry, and polygyny". Thesis, Національний авіаційний університет, 2020. https://er.nau.edu.ua/handle/NAU/49577.
Texto completoВашека, Тетяна Володимирівна y Валерія Ярославівна Юдіна. "Postmodern moral world: the changes of attitude towards sex and its connections between polyandry, and polygyny". Thesis, Національний авіаційний університет, 2020. http://er.nau.edu.ua/handle/NAU/42309.
Texto completoВашека, Тетяна Володимирівна y Валерія Ярославівна Юдіна. "Postmodern moral world: the changes of attitude towards sex and its connections between polyandry, and polygyny". Thesis, Національний авіаційний університет, 2020. https://er.nau.edu.ua/handle/NAU/54043.
Texto completoEckholm, Bruce James. "Effects of Honey Bee (Apis mellifera) Intracolonial Genetic Diversity on the Acquisition and Allocation of Protein". Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293412.
Texto completoBarth, Benjamin [Verfasser], Robin F. A. [Akademischer Betreuer] Moritz, Robert J. [Akademischer Betreuer] Paxton y Susanne [Akademischer Betreuer] Foitzik. "Causes and consequences of extreme polyandry in army ants : [kumulative Dissertation] / Benjamin Barth ; Robin F. A. Moritz, Robert J. Paxton, Susanne Foitzik". Halle, 2016. http://d-nb.info/1116952521/34.
Texto completoBarth, Benjamin Verfasser], Robin F. A. [Akademischer Betreuer] Moritz, Robert J. [Akademischer Betreuer] Paxton y Susanne [Akademischer Betreuer] [Foitzik. "Causes and consequences of extreme polyandry in army ants : [kumulative Dissertation] / Benjamin Barth ; Robin F. A. Moritz, Robert J. Paxton, Susanne Foitzik". Halle, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:3:4-17882.
Texto completoKivelä, S. M. (Sami Mikael). "Evolution of insect life histories in relation to time constraints in seasonal environments:polymorphism and clinal variation". Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514293788.
Texto completoTiivistelmä 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
Pearcy, Morgan. "Stratégies reproductrices chez la fourmi Cataglyphis cursor". Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210909.
Texto completoKin 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
McKeown, Jennifer J. "Modelling the evolution of sexual behaviour". Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/21823.
Texto completoCosta, Camila Moreira. "Ocorrência de poliandria na broca-do-café, Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae)". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-25022014-153249/.
Texto completoResearches 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.
Pirog, Agathe. "Structure génétique des populations et biologie de la reproduction chez le requin bouledogue Carcharhinus leucas et le requin tigre Galeocerdo cuvier". Thesis, La Réunion, 2018. http://www.theses.fr/2018LARE0008/document.
Texto completoThis 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
Eyer, Pierre-André. "Modes de reproduction et diversité génétique chez les fourmis du genre Cataglyphis". Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209190.
Texto completoLes 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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Wright, Lucy Isabel. "Insights into the mating systems of green turtle populations from molecular parentage analyses". Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3695.
Texto completoCroshaw, Dean. "Salamander Mating Behaviors and Their Consequences for Individuals and Populations". ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/436.
Texto completoFournier, Denis. "Population genetic structure, mating system and conflicts in Pheidole ants". Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211174.
Texto completoDoctorat en Sciences
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Boschetto, Chiara. "Meccanismi della selezione sessuale postcopulatoria in un guppy (Poecilia reticulata), un pesce teleosteo a fecondazione interna". Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425476.
Texto completoThurin, Nicolas. "Evolutions des stratégies reproductrices au sein du genre Plagiolepis (Hymenoptera: Formicidae)". Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210108.
Texto completo\
Doctorat en Sciences
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Nir, Edward Ess. "The monodominant stands of anisoptera thurifera ssp polyandra and their management in Papua New Guinea /". [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18255.pdf.
Texto completoFernandes, Heloísa Mara Batista. "Constituintes químicos e avaliação de atividades biológicas de Croton polyandrus Spreng. (Euphorbiaceae)". Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/6773.
Texto completoCoordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
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.
Le, Cam Sabrina. "Grégarité, changement de sexe et polyandrie : modalité de la reproduction chez une espèce invasive Crepidula fornicata". Paris 6, 2009. http://hal.upmc.fr/tel-01110473.
Texto completoPessoa, Déborah Ribeiro. "Estudo da toxidade e atividade antitumoral do óleo essencial de Croton Polyandrus Spreng. (Euphorbiaceae) em Modelo Experimental de Tumor Ascítico de Ehrlich". Universidade Federal da Paraíba, 2013. http://tede.biblioteca.ufpb.br:8080/handle/tede/6760.
Texto completoCoordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
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.
Devost, Éric. "Conflit sexuel et polyandrie de la commodité chez une espèce polygynandre : les effets combinés des processus pré- et post- copulatoires sur le succès reproducteur de "Gerris buenoi"". Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26725.
Texto completoIn 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.
Clemencet, Johanna. "Evolution des stratégies de dispersion et de reproduction chez la fourmi Cataglyphis cursor". Paris 6, 2006. http://www.theses.fr/2006PA066106.
Texto completoCliche, Marie-Ève. "Illusion et rhétorique de la folie comique entre 1630 et 1650 : le discours des mythomanes et des monomaniaques dans Le Menteur de Pierre Corneille, Les Visionnaires de Jean Desmarets de Saint-Sorlin et Polyandre de Charles Sorel". Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28422/28422.pdf.
Texto completoTimmermans, Iris. "Stratégies de reproduction au sein du genre Cataglyphis (Hymenoptera :Formicidae): analyse comparative". Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210238.
Texto completoLes 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
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Beltran, S. "Monogamie et changements de partenaires chez un parasite monogame, Schistosoma mansoni". Phd thesis, Université de Perpignan, 2009. http://tel.archives-ouvertes.fr/tel-00939328.
Texto completoZeh, Jeanne Anne. "Polyandry as a hedge against genetic incompatibility". Thesis, 1996. http://hdl.handle.net/1911/16945.
Texto completoFoster, Wendy. "Reproductive strategies of the red-tailed phascogale (Phascogale calura)". 2008. http://digital.library.adelaide.edu.au/dspace/handle/2440/49885.
Texto completo"March 2008" -- T.P. Includes author's previously published papers. Bibliography: pages 104-118. Also available in print form.
Rodrigues, Ana Leonor Rapoula. "Polyandry and host-endosymbiont conflicts in the spider mite tetranychus urticae". Doctoral thesis, 2017. http://hdl.handle.net/10451/30396.
Texto completoOrganisms 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.
Foster, Wendy Kay. "Reproductive strategies of the red-tailed phascogale (Phascogale calura)". Thesis, 2008. http://hdl.handle.net/2440/49885.
Texto completoThesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2008
Foster, Wendy Kay. "Reproductive strategies of the red-tailed phascogale (Phascogale calura)". 2008. http://hdl.handle.net/2440/49885.
Texto completohttp://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
Jennions, Michael Dawson. "Breeding behaviour of the foam nest frog, chiromantis xerampelina: sperm competition and polyandry". Thesis, 1992. https://hdl.handle.net/10539/25661.
Texto completoBreeding 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
Sládeček, Martin. "Vliv individuálních vlastností samic čejky chocholaté (Vanellus vanellus) na kvalitu snůšky, párovací status a inkubační úsilí samce". Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-344389.
Texto completoNeumann, Peter [Verfasser]. "The impact of polyandry and drifting on the genotypic composition of honeybee (Apis mellifera L.) colonies / von Peter Neumann". 1998. http://d-nb.info/960878742/34.
Texto completoŠevčíková, Pavlína. "Experimentální studie vlivu páření s více samci na reprodukční úspěch samice u gekončíků Eublepharis macularius". Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-296530.
Texto completoNgidi, Evangeline Bonisiwe. "The use of personal names in respect of the living-dead within traditional polygynous families in Kwamambulu, Kranskop". Thesis, 2012. http://hdl.handle.net/10413/8953.
Texto completoThesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.