Artykuły w czasopismach na temat „Hermaphroditen”
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Wolf, Diana E., Jessica A. Satkoski, Kara White i Loren H. Rieseberg. "Sex Determination in the Androdioecious Plant Datisca glomerata and Its Dioecious Sister Species D. cannabina". Genetics 159, nr 3 (1.11.2001): 1243–57. http://dx.doi.org/10.1093/genetics/159.3.1243.
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Abstract Datisca glomerata is an androdioecious plant species containing male and hermaphroditic individuals. Molecular markers and crossing data suggest that, in both D. glomerata and its dioecious sister species D. cannabina, sex is determined by a single nuclear locus, at which maleness is dominant. Supporting this conclusion, an amplified fragment length polymorphism (AFLP) is heterozygous in males and homozygous recessive in hermaphrodites in three populations of the androdioecious species. Additionally, hermaphrodite × male crosses produced 1:1 sex ratios, while hermaphrodite × hermaphrodite crosses produced almost entirely hermaphroditic offspring. No perfectly sex-linked marker was found in the dioecious species, but all markers associated with sex mapped to a single linkage group and were heterozygous in the male parent. There was no sex-ratio heterogeneity among crosses within D. cannabina collections, but males from one collection produced highly biased sex ratios (94% females), suggesting that there may be sex-linked meiotic drive or a cytoplasmic sex-ratio factor. Interspecific crosses produced only male and female offspring, but no hermaphrodites, suggesting that hermaphroditism is recessive to femaleness. This comparative approach suggests that the hermaphrodite form arose in a dioecious population from a recessive mutation that allowed females to produce pollen.
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Stackelberg, Katharine T. Von. "Garden Hybrids". Classical Antiquity 33, nr 2 (1.10.2014): 395–426. http://dx.doi.org/10.1525/ca.2014.33.2.395.
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This article discusses representations of hermaphrodites in the domestic context of Roman gardens and argues that the spatial context of the hermaphrodite body is as germane to critical understanding as the intersexed body itself. The spatial and semantic interrelations between Roman gardens and hermaphrodite images focus on the dynamics of viewing hermaphrodite types in Italo-Roman art (section 1), the spatial configuration of hermaphrodites with documented findspots (section 2), Ovid's introduction of garden imagery in the tale of Salmacis and Hermaphroditus (Met. 4. 285–388) compared to the Salmakis inscription from Kaplan Kalesi at Halicarnassus (section 3), and the historical correlation to Augustan Rome's vegetative symbolism (section 4). This synthesis of material, literary, and historical evidence for hermaphrodite images indicates that their representation in Roman domestic art can be read as an expression of domestic harmony that mirrored the emphasis on heterosexual union and political concord ushered in by Augustus and Livia.
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Luke, Kelly N., i David L. Bechler. "The role of dyadic interactions in the mixed-mating strategies of the mangrove rivulus Kryptolebias marmoratus". Current Zoology 56, nr 1 (1.02.2010): 6–17. http://dx.doi.org/10.1093/czoolo/56.1.6.
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Abstract The mangrove rivulus Kryptolebias marmoratus a small cyprinodont fish native to tropical and subtropical waters from Florida to Brazil, is one of two known self-fertilizing, hermaphroditic vertebrates of which K. marmoratus displays androdioecy, a complex system of reproduction in which hermaphrodites and males are present. This study describes the behavioral repertoires observed during dyadic interactions in the laboratory. Kryptolebias marmoratus exhibited 23 distinctive acts or behaviors. Acts were divided into four categories: aggressive, submissive, neutral, and reproductive. Leading and following behaviors played important roles in the behavioral repertoires of these fish. In hermaphrodite-male dyads, males exclusively initiated the reproductive process and actively pursued hermaphrodites. When hermaphrodites were paired, there was no evidence that they behaved like other simultaneous hermaphrodites that alternate sexual roles (e.g. serranids). Hermaphrodites were extremely aggressive towards one another, and the aggressor established dominance rapidly. Male-male dyads were divided into two subdivisions based on the presence or absence of the caudal ocellus on one fish. A caudal ocellus on one male appeared to signal the possibility of a potential mating partner to males lacking it. Pairings of males without an ocellus were similar to hermaphrodite-hermaphrodite dyads in that both members of the pair were aggressive towards one another. These observations may be indicative of interactions taking place in natural communities or assemblages of fish in which both males and hermaphrodites occur and provide evidence on the role of dyadic interactions in the mixed-mating strategies.
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Manicacci, D., i L. Després. "Male and hermaphrodite flowers in the alpine lily Lloydia serotina". Canadian Journal of Botany 79, nr 9 (1.09.2001): 1107–14. http://dx.doi.org/10.1139/b01-087.
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In perennial species that produce only one flower per individual each year, androdicy (coexistence of genetic male and hermaphrodite individuals) may be difficult to distinguish from andromoncy (male and hermaphrodite flowers on the same plant). We show that the alpine lily, Lloydia serotina Rchb., produces functionally male and hermaphroditic flowers. Mean male frequency in 11 populations in the French Alps was 48.5%, ranging from 15.5 to 67.5%. Male flowers do not produce more pollen nor sire more seeds per flower in controlled pollinations than hermaphrodite flowers. Male floral scapes were consistently shorter than those of hermaphrodites. Out of several thousand observed floral scapes, four had two flowers, all with a terminal hermaphroditic flower and an axillary male one. Among 107 bulbs transplanted in pots in 1996, eighteen expressed a different sexual phenotype in 1999 or 2000, and one hermaphrodite produced two flowers of different sexes in 2000. Together, these results suggest that L. serotina is andromoncious throughout its lifetime.Key words: Lloydia serotina, andromoncy, male reproductive success, Liliaceae.
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Mamut, Jannathan, Junhui Cheng, Dunyan Tan, Carol C. Baskin i Jerry M. Baskin. "Effect of Hermaphrodite–Gynomonoecious Sexual System and Pollination Mode on Fitness of Early Life History Stages of Offspring in a Cold Desert Perennial Ephemeral". Diversity 14, nr 4 (1.04.2022): 268. http://dx.doi.org/10.3390/d14040268.
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Gynomonoecy, the occurrence of both pistillate (female) and perfect (hermaphroditic) flowers on the same plant, has received little attention compared to gynodioecy and other plant sexual systems. Eremurus anisopterus is a perennial ephemeral in the cold desert of northwest China with a hermaphrodite–gynomonoecious sexual system in the same population. The primary aim of this study was to compare the early life history traits and inbreeding depression between progeny from pistillate and hermaphrodite flowers in hermaphrodites and gynomonoecious individuals. All of the traits of progeny from outcrossed pistillate flowers on gynomonoecious plants were significantly greater than for other pollination types. Selfing (vs. outcrossing) resulted in a decrease in all traits, indicating inbreeding depression (ID) during early life history stages of gynomonoecious and hermaphroditic plants. ID for seed mass, seed germination and seedling survivorship under water stress for pistillate flowers on gynomonoecious plants was significantly higher than it was for hermaphrodite flowers on both gynomonoecious and hermaphrodite plants. The advantage of the offspring of pistillate (vs. hermaphrodite) flowers may contribute to the maintenance of gynomonoecy in E. anisopterus in its cold desert sand dune habitat.
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Stahler, Margaret M., Peter D. Ascher, James J. Luby i Alan P. Roelfs. "Sexual composition of populations of Fragaria virginiana (Rosaceae) collected from Minnesota and western Wisconsin". Canadian Journal of Botany 73, nr 9 (1.09.1995): 1457–63. http://dx.doi.org/10.1139/b95-158.
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Populations of Fragaria virginiana Miller collected from 39 sites in Minnesota and western Wisconsin were gynodioecious, in that 35% of the plants were pistillate, 65% were hermaphroditic with perfect flowers, and none were staminate, when scored for gender expression in greenhouse or field plantings. Instability of gender expression across environments was apparent in 15% of the collections and these genotypes that appeared to change gender were termed weak hermaphrodites. Variation in gender composition of collections was not related in any consistent manner with the plant communities characterizing the collection sites. The proportions of pistillate plants, total hermaphrodites, strong hermaphrodites, and weak hermaphrodites in collections from the northern forest floristic province in the northeastern part of the region were not significantly different from those of collections from the southwestern prairie-forest floristic region, although collections from the prairie-forest province were more variable for gender composition than populations from the northern forest province. Lack of staminate plants and increased percentages of hermaphrodite plants, relative to reports in the literature, suggest that the gender composition of F. virginiana populations in Minnesota has changed, perhaps as a result of introgression from hermaphroditic Fragaria ×ananassa or Fragaria vesca. Key words: Fragaria chiloensis, Fragaria vesca, Fragaria ×ananassa, dioecy, introgression, evolution.
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LaMunyon, C. W., i S. Ward. "Assessing the viability of mutant and manipulated sperm by artificial insemination of Caenorhabditis elegans." Genetics 138, nr 3 (1.11.1994): 689–92. http://dx.doi.org/10.1093/genetics/138.3.689.
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Abstract We describe a protocol for artificial insemination of Caenorhabditis elegans which we used to evaluate the viability of sperm from different strains and of sperm activated in vitro. Worms can be artificially inseminated with almost 100% success. Both male and hermaphrodite sperm can be used for insemination. Sperm from a sterile hermaphrodite [fem-3(q23ts)] were found to be viable. As with normal mating, male sperm inseminated into hermaphrodites artificially outcompete the hermaphrodite's own sperm, even though they have not been ejaculated with seminal fluid. Spermatozoa that were activated in vitro from spermatids by the weak base triethanolamine were viable. In contrast, spermatozoa activated in vitro by protease treatment were not.
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Limbeck, Sven. "Rebis. Bilder von Hermaphroditen als Medien alchemischer Erkenntnis". Sexuologie. Zeitschrift für Sexualmedizin, Sexualtherapie und Sexualwissenschaft 24, nr 3-4 (grudzień 2017): 125–38. http://dx.doi.org/10.61387/s.2017.34.32.
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Chasnov, J. R., i King L. Chow. "Why Are There Males in the Hermaphroditic Species Caenorhabditis elegans?" Genetics 160, nr 3 (1.03.2002): 983–94. http://dx.doi.org/10.1093/genetics/160.3.983.
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Abstract The free-living nematode worm Caenorhabditis elegans reproduces primarily as a self-fertilizing hermaphrodite, yet males are maintained in wild-type populations at low frequency. To determine the role of males in C. elegans, we develop a mathematical model for the genetic system of hermaphrodites that can either self-fertilize or be fertilized by males and we perform laboratory observations and experiments on both C. elegans and a related dioecious species C. remanei. We show that the mating efficiency of C. elegans is poor compared to a dioecious species and that C. elegans males are more attracted to C. remanei females than they are to their conspecific hermaphrodites. We postulate that a genetic mutation occurred during the evolution of C. elegans hermaphrodites, resulting in the loss of an attracting sex pheromone present in the ancestor of both C. elegans and C. remanei. Our findings suggest that males are maintained in C. elegans because of the particular genetic system inherited from its dioecious ancestor and because of nonadaptive spontaneous nondisjunction of sex chromosomes, which occurs during meiosis in the hermaphrodite. A theoretical argument shows that the low frequency of male mating observed in C. elegans can support male-specific genes against mutational degeneration. This results in the continuing presence of functional males in a 99.9% hermaphroditic species in which outcrossing is disadvantageous to hermaphrodites.
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Olito, Colin, Jessica K. Abbott i Crispin Y. Jordan. "The interaction between sex-specific selection and local adaptation in species without separate sexes". Philosophical Transactions of the Royal Society B: Biological Sciences 373, nr 1757 (27.08.2018): 20170426. http://dx.doi.org/10.1098/rstb.2017.0426.
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Local adaptation in hermaphrodite species can be based on a variety of fitness components, including survival, as well as both female and male sex-functions within individuals. When selection via female and male fitness components varies spatially (e.g. due to environmental heterogeneity), local adaptation will depend, in part, on variation in selection through each fitness component, and the extent to which genetic trade-offs between sex-functions maintain genetic variation necessary for adaptation. Local adaptation will also depend on the hermaphrodite mating system because self-fertilization alters several key factors influencing selection and the maintenance of genetic variance underlying trade-offs between the sex-functions (sexually antagonistic polymorphism). As a first step to guide intuition regarding sex-specific adaptation in hermaphrodites, we develop a simple theoretical model incorporating the essential features of hermaphrodite mating and adaptation in a spatially heterogeneous environment, and explore the interaction between sex-specific selection, self-fertilization and local adaptation. Our results suggest that opportunities for sex-specific local adaptation in hermaphrodites depend strongly on the extent of self-fertilization and inbreeding depression. Using our model as a conceptual framework, we provide a broad overview of the literature on sex-specific selection and local adaptation in hermaphroditic plants and animals, emphasizing promising future directions in light of our theoretical predictions. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences'.
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Stănică, Mihaela Gabriela. "Comment représenter la transgression de genre - L'Hermaphrodite dans l'oeuvre de J. K. Huysmans -". Nordlit 15, nr 2 (26.03.2012): 197. http://dx.doi.org/10.7557/13.2055.
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By the end of the 19th century one may observe the birth of a particular form of knowledge which would further be known as scientia sexualis as well as the rationalization of the hermaphroditic body. Ernest Martin’s attempt to realize a taxonomy of the different forms of monstrosity (Histoire des monstres depuis l’Antiquité jusqu’à nos jours -1880) from a juridical and clinical perspective is representative for what Jean-Jacques Courtine will call “le désenchantement de l’étrange”.Since the physicians from that period refuse to acknowledge the existence of real hermaphrodites among humans, the pseudo-hermaphrodite will lose his ontological independence and will turn into a simple pathological deviation which will be placed among the other pathological figures which constitute the inventory of degenerationshaunting the imaginary of the fin de siècle. Since the hermaphroditic body, this gender trouble that threatens the dual taxonomy of the society, is denied the ontological independence, this body enters the sphere of invisibility. Given that the transgressive body becomes a simple deviation, the hermaphrodite can only be a secondary representation.How are these mechanisms of the secondary representation applied to the literary productions of that period? The answer to this question could be found in Huysmans’ texts where the ambiguity of the hermaphroditic figure is captured into somatic and psychical representations that seem to confirm the epistemic paradigms of that fin de siècle.
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Stock, S. Patricia, Christine T. Griffin i Rani Chaerani. "Morphological and molecular characterisation of Steinernema hermaphroditum n. sp. (Nematoda: Steinernematidae), an entomopathogenic nematode from Indonesia, and its phylogenetic relationships with other members of the genus". Nematology 6, nr 3 (2004): 401–12. http://dx.doi.org/10.1163/1568541042360555.
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Abstract Steinernema hermaphroditum n. sp., a new entomopathogenic nematode isolated from soil samples in the Moluccan islands, Indonesia, is described. Morphological observations as well as biological evidence (cross-hybridisation studies) indicate the distinctness of S. hermaphroditum n. sp. from other Steinernema spp. This new species is characterised by the presence of hermaphrodites in the first adult generation. Key morphological diagnostic characters include: a digitate tail with a mucro and a glandular spermatheca filled with sperm in the first generation hermaphrodite; the value of D%; the morphology of the male spicules and gubernaculum and the number and arrangement of the genital papillae; the values of D%, E% and the pattern of the lateral field of the third-stage infective juvenile. Additionally, molecular evidence obtained from ITS rDNA RFLP profiles, 28S rDNA sequence analyses, and phylogenetic reconstruction provide further evidence to establish this nematode as a new species.
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Felmy, Anja, Nora Weissert, Joseph Travis i Jukka Jokela. "Mate availability determines use of alternative reproductive phenotypes in hermaphrodites". Behavioral Ecology 31, nr 4 (20.05.2020): 1003–16. http://dx.doi.org/10.1093/beheco/araa046.
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Abstract In many species, individuals can employ alternative reproductive phenotypes, with profound consequences for individual fitness and population dynamics. This is particularly relevant for self-compatible hermaphrodites, which have exceptionally many reproductive options. Here we investigated the occurrence of reproductive phenotypes in the simultaneously hermaphroditic freshwater snail Radix balthica under experimentally simulated conditions of low versus moderate population density. We captured all mating behavior on camera and measured individual female lifetime reproductive success. We found every possible reproductive phenotype: (1) both male and female (i.e., truly hermaphroditic) reproduction, (2) purely female and (3) purely male reproduction, (4) male reproduction combined with self-fertilization and (5) female mating activity, (6) pure self-fertilization without mating and (7–8) two types of reproductive failure. Variation in alternative reproductive phenotypes was explained by mate availability (10.8%) and individual condition, approximated by a snail’s mean daily growth rate (17.5%). Increased mate availability resulted in a lower diversity of reproductive phenotypes, in particular increasing the frequency of true hermaphrodites. However, it lowered phenotype-specific fecundities and hence reduced the population growth rate. Snails in better condition were more likely to reproduce as true hermaphrodites or pure females, whereas low-condition snails tended to suffer reproductive failure. Overall, we show substantial variation in alternative reproductive phenotypes in a hermaphrodite, which is possibly in part maintained by fluctuations in population density and thus mate availability, and by variation in individual condition. We also provide evidence of an almost 2-fold increase in clutch size that can be ascribed specifically to mating as a female.
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Banks, J. A. "Sex-determining genes in the homosporous fern Ceratopteris". Development 120, nr 7 (1.07.1994): 1949–58. http://dx.doi.org/10.1242/dev.120.7.1949.
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Haploid Ceratopteris gametophytes are either hermaphroditic or male. The determinate of sex type is the pheromone antheridiogen (ACE) which is secreted by the meristic hermaphrodite and promotes ameristic male development of sexually undetermined gametophytes. Several mutations effecting the sex of the haploid gametophyte have been isolated and are described. The hermaphroditic (her) mutants are insensitive to ACE and develop as meristic hermaphrodites. These mutations effect ameristic male development in the presence of ACE but have no effect on hermaphroditic development. While most her mutations also have no effect on diploid sporophyte development, some partially ACE-insensitive her mutations have profound effects on sporophyte development. The transformer (tra) mutation effects both meristem and archegonia formation and causes the gametophyte to be an ameristic male under conditions that promote hermaphroditic development. The feminization (fem) mutation effects antheridia development in both male and hermaphroditic gametophytes and causes the gametophyte to develop as a meristic female in the absence or presence of the pheromone. The her1 tra1 double mutant is male in the absence or presence of ACE, indicating that tra1 is epistatic to her1. The phenotypes of her1, tra1 and fem1 single gene mutant phenotypes and the her1 tra1 double mutant phenotype are used to deduce a model suggesting how the products of these genes might interact in a regulatory pathway to control sex determination.
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Krämer, Fabian. "Die Individualisierung des Hermaphroditen in Medizin und Naturgeschichte des 17. Jahrhunderts". Berichte zur Wissenschaftsgeschichte 30, nr 1 (marzec 2007): 49–65. http://dx.doi.org/10.1002/bewi.200701235.
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Azziz, Raouane, Ruhi Fadzlyana Jailani i Mualimin Mochammad Sahid. "Integrating Islamic Ruling and the Medical Concept: A Study of the Hermaphrodite Inheritance". global journal al thaqafah 12, nr 2 (31.12.2022): 172–82. http://dx.doi.org/10.7187/gjat122022-11.
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Determining the gender of the heirs is important in the ruling of Islamic inheritance. Hence, Muslim jurists made efforts in determining the gender of hermaphrodites. Taking the safer position, the common practice is for the inheritance to be divided into two: the greater part of the share is withheld and the lesser portion is given out to the hermaphroditic inheritors along with their heirs until their gender is certified. This typically leads to disagreements among the jurists, hence, subsequently leading to a tedious process of certification. This protracted disagreement combined with a much prolonged certification process may harm the inheritors’ right due to the delay in judgement. This research aims to define the biological identity of a hermaphrodite and determine his sex according to the medical concept, as well as integrating the methods adopted by Muslim scholars to solve the issue of hermaphrodite inheritance. Both descriptive and analytical approaches are used in ensuring accurate knowledge transfer and trust in attribution. This research has found that the medical definition of a hermaphrodite is the most accurate and the most correct to end the dispute when dividing inheritance. Hence, this opens a wider area for further research that relies on medical information as evidence to be taken when studying Islamic legal rulings in ensuring the cohesion of society by preserving the rights of its members and maintaining their material and moral properties.
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Johnson, T. E., i E. W. Hutchinson. "Absence of strong heterosis for life span and other life history traits in Caenorhabditis elegans." Genetics 134, nr 2 (1.06.1993): 465–74. http://dx.doi.org/10.1093/genetics/134.2.465.
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Abstract We have examined crosses between wild-type strains of Caenorhabditis elegans for heterosis effects on life span and other life history traits. Hermaphrodites of all wild strains had similar life expectancies but males of two strains had shorter life spans than hermaphrodites while males of two other strains lived longer than hermaphrodites. F1 hermaphrodite progeny showed no heterosis while some heterosis for longer life span was detected in F1 males. F1 hybrids of crosses between two widely studied wild-type strains, N2 (var. Bristol) and Berg BO (var. Bergerac), were examined for rate of development, hermaphrodite fertility, and behavior; there was no heterosis for these life history traits. Both controlled variation of temperature and uncontrolled environmental variation affected the length of life of all genotypes. Significant G x E effects on life span were observed in comparisons of N2 and Berg BO hermaphrodites, or N2 hermaphrodites and males, or N2 and a Ts mutant strain (DH26). Nevertheless, within an experiment, environmental variation was minimal and life spans were quite replicable.
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Landry, Carol L., i Beverly J. Rathcke. "Insect visitation rates and foraging patterns differ in androdioecious and hermaphrodite-only populations of Laguncularia racemosa (Combretaceae) in Florida". Journal of Tropical Ecology 28, nr 4 (1.06.2012): 343–51. http://dx.doi.org/10.1017/s0266467412000296.
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Abstract:Insect-pollinated Laguncularia racemosa has a variable breeding system; some populations are androdioecious, with male and hermaphroditic plants, while others lack male plants. We observed the foraging behaviours of insects in three androdioecious and three hermaphrodite-only populations of L. racemosa in Florida. In each population, insect visitation rates were estimated from 30–108 timed intervals. We recorded the number of flowers visited by 144–224 insects during foraging bouts made to 15–40 male and hermaphroditic plants. Male plants in androdioecious populations had significantly more visitors than hermaphroditic plants, increasing the number of vectors carrying pollen from male plants. Further, many insects visited few flowers during foraging bouts, which should increase outcrossing frequency. According to mathematical models, male plants benefit from these combined factors. Plants in hermaphrodite-only populations had significantly more visitors than hermaphroditic plants in androdioecious populations. Proportionately more insects visited many flowers during foraging bouts in hermaphrodite-only versus androdioecious populations. The increased likelihood of geitonogamous self-pollination could help explain the lack of male plants in hermaphrodite-only populations. Differences in pollinator assemblages and the relative abundances of several species were responsible for differences in foraging behaviours: Apis mellifera, Bombus sp., Melissodes sp., Xylocopa sp., Euodynerus sp. and a calliphorid species.
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Prokic, Branislav, Dusan Milijevic, Verica Mrvic i Bogomir Prokic. "Corrective surgery of external sexual organs in female pseudo hermaphrodite dog". Veterinarski glasnik 65, nr 5-6 (2011): 443–50. http://dx.doi.org/10.2298/vetgl1106443p.
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Hermaphroditism is a congenital anomaly characterized by the presentation of sexual characteristics of both sexes in one individual. Hermaphrodites can occur in every mammal species. Real and pseudo hermaphrodites can be distinguished. Both ovaries and testes (ovotestes) are presented in real hermaphrodites, while the conformation of the individual does not correspond to any sex in particular. Pseudo hermaphrodites are more frequent. Male pseudo hermaphrodites have testes and female external genital characteristics, while female pseudo hermaphrodites have ovaries and rudimentary external genitals reassembling to masculine ones. Corrective surgical removal of a rudimental penis in a female pseudo hermaphrodite dog is presented in the paper.
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Cuevas-García, Eduardo, i César A. Abarca-García. "Origen, mantenimiento y evolución del ginodioicismo". Botanical Sciences, nr 78 (3.06.2017): 33. http://dx.doi.org/10.17129/botsci.1719.
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One of the main characteristics of Angiosperms is the great diversity of reproductive systems they present. Gynodioecy, namely the coexistence of hermaphrodite and female plants in the same population, is an example of such diversity. In this study we present the main characteristics of gynodioecious species, such as the large variation in female frequency among populations. We examine the three forms by which male sterility can be originated and transmitted, and their consequences for the evolutionary dynamics. We present and discuss the hypothesis that would explain the maintenance of females in populations, since due to the lack of male function, they need to produce more or better seeds than hermaphrodites to avoid a disadvantage. We analyze the main evolutionary routes beginning from a hermaphroditic condition, and the existing evidences that suggest gynodioecy as the main path in the evolution of dioecy. Finally, we analyze the present state of the investigation of reproductive systems in Mexico, using as an example the study of the gynodioecy.
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Yu, Tong Lei, Yao Hui Deng, Juan Zhang i Li Peng Duan. "Size-assortative copulation in the simultaneously hermaphroditic pond snail Radix auricularia (Gastropoda: Pulmonata)". Animal Biology 66, nr 3-4 (2016): 239–47. http://dx.doi.org/10.1163/15707563-00002501.
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To better understand the importance of body size in hermaphroditic mating, we studied the mating behaviour of the pond snail Radix auricularia. This simultaneous hermaphrodite exhibits a positive correlation between body size and egg production and provides weak evidence for size-assortative mating. In addition to this mating pattern, the partner performing the male role was significantly smaller than the mounted partner, performing the female role. In this study, two laboratory experiments were done to test whether body size has (1) an effect on mate choice of the sperm donor, and (2) poses mechanical constraints. These snails did not display physical limitation in mating with a much larger or smaller partner. In the mate choice experiment, we found no evidence for significant preferences for large partners. Therefore, mate choice of sperm donor and mechanical constraints are not likely to contribute to the formation of size-assortatively mating pairs in this species, which contributes to understanding about how these processes work in hermaphrodites.
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Abbott, Jessica K. "Intra-locus sexual conflict and sexually antagonistic genetic variation in hermaphroditic animals". Proceedings of the Royal Society B: Biological Sciences 278, nr 1703 (18.08.2010): 161–69. http://dx.doi.org/10.1098/rspb.2010.1401.
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Intra-locus sexual conflict results when sex-specific selection pressures for a given trait act against the intra-sexual genetic correlation for that trait. It has been found in a wide variety of taxa in both laboratory and natural populations, but the importance of intra-locus sexual conflict and sexually antagonistic genetic variation in hermaphroditic organisms has rarely been considered. This is not so surprising given the conceptual and theoretical association of intra-locus sexual conflict with sexual dimorphism, but there is no a priori reason why intra-locus sexual conflict cannot occur in hermaphroditic organisms as well. Here, I discuss the potential for intra-locus sexual conflict in hermaphroditic animals and review the available evidence for such conflict, and for the existence of sexually antagonistic genetic variation in hermaphrodites. I argue that mutations with asymmetric effects are particularly likely to be important in mediating sexual antagonism in hermaphroditic organisms. Moreover, sexually antagonistic genetic variation is likely to play an important role in inter-individual variation in sex allocation and in transitions to and from gonochorism (separate sexes) in simultaneous hermaphrodites. I also describe how sequential hermaphrodites may experience a unique form of intra-locus sexual conflict via antagonistic pleiotropy. Finally, I conclude with some suggestions for further research.
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PANNELL, JOHN R. "Consequences of inbreeding depression due to sex-linked loci for the maintenance of males and outcrossing in branchiopod crustaceans". Genetics Research 90, nr 1 (luty 2008): 73–84. http://dx.doi.org/10.1017/s0016672307008981.
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SummaryAndrodioecy, where males co-occur with hermaphrodites, is a rare sexual system in plants and animals. It has a scattered phylogenetic distribution, but it is common and has persisted for long periods of evolutionary time in branchiopod crustaceans. An earlier model of the maintenance of males with hermaphrodites in this group, by Ottoet al.(1993), considered the importance of male–hermaphrodite encounter rates, sperm limitation, male versus hermaphrodite viability and inbreeding depression suffered by selfed progeny. Here I advance this model in two ways: (1) by exploring the conditions that would allow the invasion of hermaphrodites into a dioecious population and that of females into an androdioecious population; and (2) by incorporating a term that accounts for the potential effects of genetic load linked to a dominant hermaphrodite-determining allele in androdioecious populations. The new model makes plausible sense of observations made in populations of the speciesEulimnadia texana, one of a number of related species whose common ancestor evolved hermaphroditism (and androdioecy) from dioecy. In particular, it offers an explanation for the long evolutionary persistence of androdioecy in branchiopods and suggests reasons for why dioecy has not re-evolved in the clade. Finally, it provides a rather unusual illustration of the implications of the degeneration of loci linked to a sex-determining locus.
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Leonard, Janet L. "Sexual selection and hermaphroditic organisms: Testing theory". Current Zoology 59, nr 4 (1.08.2013): 579–88. http://dx.doi.org/10.1093/czoolo/59.4.579.
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Abstract Sexual selection is widespread if not ubiquitous in hermaphroditic organisms. Although many phenomena that have been described as sexual selection in gonochores, (e.g. harem polygamy, multiple mating, elaborate courtship, even secondary sexual characters) can be found in some hermaphrodites, what is more interesting is the ways in which sexual selection in hermaphrodites may differ from dioecious taxa. In hermaphrodites, an individual’s mating success includes its success from both sexual roles. Secondly, in many simultaneously hermaphroditic taxa there is strong evidence of sexual selection and yet the operational sex ratio is 1:1, by definition. Many simultaneous hermaphrodites have elaborate courtship and genital anatomy, suggesting sexual selection plays an important role in reproductive success. Sperm competition and cryptic female choice mean that the number of mates acquired is not necessarily a predictor of reproductive success. Even in simultaneous hermaphrodites with reciprocal mating, variance in reproductive success through the male role and through the female role may differ in a population. Moreover hermaphrodites may choose to emphasize one sexual role over the other. Data suggest that the preferred role varies in hermaphrodites, which creates an opportunity to test fundamental predictions and assumptions of sexual selection theory. Hermaphrodites may vary their emphasis on one sexual role over the other either developmentally or behaviorally in response to environmental or social parameters. How they use this capability in acquiring more or higher quality mates still requires study.
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Collareta, Alberto. "Discovery of complemental males in a Pliocene accumulation of Chelonibia testudinaria (LINNAEUS, 1758), with some notes on the evolution of androdioecy in turtle barnacles". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 297, nr 2 (1.08.2020): 193–203. http://dx.doi.org/10.1127/njgpa/2020/0920.
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While mostly hermaphrodite, thoracican cirripedes (stalked and acorn barnacles) are remarkable in presenting also androdioecy and dioecy. With few androdioecious exceptions, the majority of the acorn barnacles of the order Balanomorpha are hermaphroditic. One of the balanomorphs in which androdioecy has been verified is the turtle barnacle Chelonibia testudinaria (Linnaeus, 1758) (Coronuloidea: Chelonibiidae), an epibiont represented by various morphs found on several hosts, including sea turtles, crabs, horseshoe crabs, sirenians, sea snails, sea snakes and crocodylians. An accumulation of shells of C. testudinaria from the late Pliocene of Italy is here reappraised, and com- plemental males are discovered among them. These complemental males consist of miniature shells occurring largely on the radii of much larger hermaphrodites, a condition known for living C. testudinaria. To the author's knowledge, this record represents the first report of fossilized complemental males for a member of Balanomorpha worldwide. The evolution and persistence of miniature males in C. testudinaria is likely due to their insuring cross-fertilization when distances between neighbouring hermaphrodites are great and speeding the rate of reproduction in this relatively short-lived species. Chelonibia testudinaria is known from fossil specimens as old as the Pliocene and the record herein demonstrates that androdioecy evolved in the lineage of C. testudinaria not later than the Piacenzian. It is thus tempting to propose that a combination of high phenotypic plasticity, diverse host habits, and androdioecy is responsible for the persistence of C. testudinaria, a refugial species.
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Gems, David, i Donald L. Riddle. "Genetic, Behavioral and Environmental Determinants of Male Longevity in Caenorhabditis elegans". Genetics 154, nr 4 (1.04.2000): 1597–610. http://dx.doi.org/10.1093/genetics/154.4.1597.
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Abstract Males of the nematode Caenorhabditis elegans are shorter lived than hermaphrodites when maintained in single-sex groups. We observed that groups of young males form clumps and that solitary males live longer, indicating that male-male interactions reduce life span. By contrast, grouped or isolated hermaphrodites exhibited the same longevity. In one wild isolate of C. elegans, AB2, there was evidence of copulation between males. Nine uncoordinated (unc) mutations were used to block clumping behavior. These mutations had little effect on hermaphrodite life span in most cases, yet many increased male longevity even beyond that of solitary wild-type males. In one case, the neuronal function mutant unc-64(e246), hermaphrodite life span was also increased by up to 60%. The longevity of unc-4(e120), unc-13(e51), and unc-32(e189) males exceeded that of hermaphrodites by 70–120%. This difference appears to reflect a difference in sex-specific life span potential revealed in the absence of male behavior that is detrimental to survival. The greater longevity of males appears not to be affected by daf-2, but is influenced by daf-16. In the absence of male-male interactions, median (but not maximum) male life span was variable. This variability was reduced when dead bacteria were used as food. Maintenance on dead bacteria extended both male and hermaphrodite longevity.
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Haag, Eric S., i Judith Kimble. "Regulatory Elements Required for Development of Caenorhabditis elegans Hermaphrodites Are Conserved in the tra-2 Homologue of C. remanei, a Male/Female Sister Species". Genetics 155, nr 1 (1.05.2000): 105–16. http://dx.doi.org/10.1093/genetics/155.1.105.
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Abstract The Caenorhabditis elegans hermaphrodite is essentially a female that produces sperm. In C. elegans, tra-2 promotes female fates and must be repressed to achieve hermaphrodite spermatogenesis. In an effort to learn how mating systems evolve, we have cloned tra-2 from C. remanei, the closest gonochoristic relative of C. elegans. We found its structure to be similar to that of Ce-tra-2 but its sequence to be divergent. RNA interference demonstrates that Cr-tra-2 promotes female fates. Two sites of tra-2 regulation are required for the onset of hermaphrodite spermatogenesis in C. elegans. One, the MX region of TRA-2, is as well conserved in C. remanei as it is in C. briggsae (another male/hermaphrodite species), suggesting that this control is not unique to hermaphrodites. Another, the DRE/TGE element of the tra-2 3′ UTR, was not detected by sequence analysis. However, gel-shift assays demonstrate that a factor in C. remanei can bind specifically to the Cr-tra-2 3′ UTR, suggesting that this translational control is also conserved. We propose that both controls are general and do not constitute a novel “switch” that enables sexual mosaicism in hermaphrodites. However, subtle quantitative or qualitative differences in their employment may underlie differences in mating system seen in Caenorhabditis.
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WEDEKIND, C., D. STRAHM i L. SCHÄRER. "Evidence for strategic egg production in a hermaphroditic cestode". Parasitology 117, nr 4 (październik 1998): 373–82. http://dx.doi.org/10.1017/s0031182098003114.
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The cestode Schistocephalus solidus is a simultaneous hermaphrodite that grows in 2 intermediate hosts and reproduces rapidly within a few days in the gut of a bird. Reproduction takes place by self- or cross-fertilization. Here, it was tested whether egg production differs between S. solidus that reproduce alone and those that are allowed to reproduce in pairs. Egg production in an in vitro system was found to depend on the cestodes' social situation. When kept alone, larger cestodes produced larger eggs. This was not so when kept in pairs – the difference between these 2 reproductive modes being highly significant in this respect. Further experiments revealed that, within the first 3 days, these hermaphrodites produced a larger total egg mass when kept alone than when kept in pairs. This was also reflected by the energy contents of the cestodes after this time-span: selfers had used up more energy than paired worms. Furthermore, S. solidus appeared to adjust its investment per egg depending on whether the offspring will be the result of self- or cross-fertilization. Selfers produced larger numbers of eggs, but these eggs were smaller and contained even smaller embryos per given egg size than eggs of potentially outbreeding cestodes. Selfed eggs reached lower hatching rates. Although this is to be expected from inbreeding depression it may also be an effect of the reduced maternal investment per egg. The observed phenotypic plasticity in the reproduction of S. solidus is discussed within 4 evolutionary frameworks: local mate competition adjusted for hermaphrodites, the hermaphrodite's dilemma, bet-hedging, and sib-competition.
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Nance, Jeremy, Alicia N. Minniti, Cathryn Sadler i Samuel Ward. "spe-12 Encodes a Sperm Cell Surface Protein That Promotes Spermiogenesis in Caenorhabditis elegans". Genetics 152, nr 1 (1.05.1999): 209–20. http://dx.doi.org/10.1093/genetics/152.1.209.
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Abstract During spermiogenesis, Caenorhabditis elegans spermatids activate and mature into crawling spermatozoa without synthesizing new proteins. Mutations in the spe-12 gene block spermatid activation, rendering normally self-fertile hermaphrodites sterile. Mutant males, however, are fertile. Surprisingly, when mutant hermaphrodites mate with a male, their self-spermatids activate and form functional spermatozoa, presumably due to contact with male seminal fluid. Here we show that, in addition to its essential role in normal activation of hermaphrodite-derived spermatids, SPE-12 also plays a supplementary but nonessential role in mating-induced activation. We have identified the spe-12 gene, which encodes a novel protein containing a single transmembrane domain. spe-12 mRNA is expressed in the sperm-producing germ line and the protein localizes to the spermatid cell surface. We propose that SPE-12 functions downstream of both hermaphrodite- and male-derived activation signals in a spermatid signaling pathway that initiates spermiogenesis.
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Petersen, Christopher W. "The Relationships Among Population Density, Individual Size, Mating Tactics, and Reproductive Success in a Hermaphroditic Fish, Serranus Fasciatus". Behaviour 113, nr 1-2 (1990): 57–80. http://dx.doi.org/10.1163/156853990x00437.
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AbstractThe hermaphroditic reef fish Serranus fasciatus exhibits three types of social systems. The size of a social group is correlated with the local density of conspecifics. At very low densities, isolated pairs of individuals reciprocally spawn with each other, achieving equal current reproductive success. At intermediate group sizes, harems form, with the largest individual typically losing all of its female function and becoming a functional male. In harems, subordinate hermaphrodites obtain little male reproductive success through streaking, an alternative male mating tactic. The lone pure male maintains almost total monopolization of male reproductive success in harems, apparently due to aggressive domination of subordinates. At high group sizes, the ability of the male to monopolize all of the matings in a social group decreases, and some of the larger hermaphrodites obtain some male-role reproductive success by pair spawning with smaller subordinate hermaphrodites while continuing to spawn as females with the male. Mating partners stay relatively constant through time, resulting in a pattern of small 'sub-harems' within harems. These mating tactics are consistent with the hypothesis that dominant individuals increase their current reproductive success in this species by restricting male mating opportunities of conspecifics. Subordinate individuals spawn as males when the dominant is unable to restrict interactions between hermaphrodites that are potential mates, or when they successfully streak. The increased male reproductive success of hermaphrodites in isolated pairs and complex harems compared with hermaphrodites in harems appears to be important in maintaining a hermaphroditic subordinate phenotype in this largely non-reciprocating species.
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Wolfe, Lorne M. "REGULATION OF SEX EXPRESSION IN DESERT AND MEDITERRANEAN POPULATIONS OF AN ANDROMONOECIOUS PLANT (GAGEA CHLORANTHA, LILIACEAE)". Israel Journal of Plant Sciences 46, nr 1 (13.05.1998): 17–25. http://dx.doi.org/10.1080/07929978.1998.10676703.
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This study examined issues related to the ecology of andromonoecy in Gagea chlorantha (Liliaceae), a perennial geophyte that grows in desert and Mediterranean-type habitats in Israel. Andromonoecy is a plant sexual system where individuals produce both male and hermaphrodite flowers and is thought to have evolved to optimize resource allocation to male and female function. Individuals of this species produced 1–6 flowers, and flower production was significantly correlated with the size of the storage organ (bulb). Three sexual phenotypes were found to exist: those that made only male flowers, plants that made only hermaphrodite flowers, and those that produced both flower types. Two lines of evidence suggest that hermaphroditic reproduction is more costly than male reproduction: (1) hermaphroditic flowers were heavier than male flowers in terms of dry biomass; (2) bulb size was greater on single-flower plants that were hermaphrodite compared to male. In addition, bulb size was greater on multiple-flowered plants that made a hermaphrodite flower as the last flower, compared to those that made a male flower. The floral sex ratio varied extensively along a latitudinal rainfall gradient within Israel. The five Mediterranean populations were male-biased. In contrast, the production of males in the three Negev desert populations was extremely rare, and approximately 94% of the flowers were hermaphrodite. The difference in sex ratio between the two habitat types is explained in terms of environmental unpredictability.
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RESNICK, IRVEN M. "ALBERT THE GREAT ON NATURE AND THE PRODUCTION OF HERMAPHRODITES: THEORETICAL AND PRACTICAL CONSIDERATIONS". Traditio 74 (2019): 307–34. http://dx.doi.org/10.1017/tdo.2019.10.
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Despite its rarity, hermaphroditism is often discussed in medieval texts in theoretical and practical contexts by canonists, theologians, and natural philosophers. For the canonist or theologian, hermaphroditism raised questions concerning baptism, marriage, entry to clerical orders, and legal status. For the natural philosopher, the hermaphrodite seemed to violate the strict dichotomy of male and female. Here I examine Albert the Great's natural-philosophical treatment of hermaphroditism. Albert rejects the view that hermaphrodites constitute a “third sex” and instead invokes Aristotle's authority to show that hermaphrodites are a “monstrous” flaw in nature. He carefully investigates the manner in which nature produces hermaphrodites in the womb and introduces a discussion of the generative capacity of hermaphrodites themselves. He concludes that they are incapable of reproducing in and of themselves (i.e., they are incapable of auto-fecundation) although they seem able to generate in another individual through coition.
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Orlando, Edward F., Yoshinao Katsu, Shinichi Miyagawa i Taisen Iguchi. "Cloning and differential expression of estrogen receptor and aromatase genes in the self-fertilizing hermaphrodite and male mangrove rivulus, Kryptolebias marmoratus". Journal of Molecular Endocrinology 37, nr 2 (październik 2006): 353–65. http://dx.doi.org/10.1677/jme.1.02101.
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The mechanisms underlying sex determination and differentiation in fishes are labile in response to environmental parameters. Sex-specific phenotypes are largely regulated by sex steroids, and the inhibition or the stimulation of aromatase can reverse sex as well as alter secondary sexual characteristics in fishes. Among vertebrates, the mangrove rivulus is the only known self-fertilizing hermaphrodite. Throughout most of its range, rivulus appear to exist as clonally reproducing hermaphrodites. However, outcrossing has been documented in Belize, where up to 25% of rivulus collected are males. The direct development of (primary) males occurs when embryos are incubated at 18 °C and hermaphrodites develop into secondary males when held at 28 °C. Given the importance of sex steroids, their receptors, and aromatase in sex determination and differentiation of fishes, we cloned, sequenced, and quantified the expression of estrogen receptors (ERα, ERβ) and ovarian (AroA) and brain (AroB) aromatase genes. Hermaphrodites had increased ERα, ERβ, AroA, and AroB gene expression in the liver, gonad, gonad, and brain respectively, compared to males. These data are consistent with the gene expression data reported for other species and are reflective of the presence of ovarian tissue in the hermaphrodites. Interestingly, we show the elevated expression of brain aromatase in the hermaphrodite brain. The role of the dimorphic expression of brain aromatase in the regulation of sex-specific characteristics is intriguing and requires further research. Because of the uniqueness of its reproductive biology, rivulus is an excellent model for elucidating the mechanisms regulating vertebrate sex determination and sexual differentiation.
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Barton, M. Kathryn, Timothy B. Schedl i Judith Kimble. "Gain-of-Function Mutations of fem-3, a Sex-Determination Gene in Caenorhabditis elegans". Genetics 115, nr 1 (1.01.1987): 107–19. http://dx.doi.org/10.1093/genetics/115.1.107.
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ABSTRACT We have isolated nine gain-of-function (gf) alleles of the sex-determination gene fem-3 as suppressors of feminizing mutations in fem-1 and fem-2. The wild-type fem-3 gene is needed for spermatogenesis in XX self-fertilizing hermaphrodites and for male development in both soma and germ line of XO animals. Loss-of-function alleles of fem-3 transform XX and XO animals into females (spermless hermaphrodites). In contrast, fem-3(gf) alleles masculinize only one tissue, the hermaphrodite germ line. Thus, XX fem-3(gf) mutant animals have a normal hermaphrodite soma, but the germ line produces a vast excess of sperm and no oocytes. All nine fem-3(gf) alleles are temperature sensitive. The temperature-sensitive period is from late L4 to early adult, a period just preceding the first signs of oogenesis. The finding of gain-of-function alleles which confer a phenotype opposite to that of loss-of-function alleles supports the idea that fem-3 plays a critical role in germ-line sex determination. Furthermore, the germ-line specificity of the fem-3(gf) mutant phenotype and the late temperature-sensitive period suggest that, in the wild-type XX hermaphrodite, fem-3 is negatively regulated so that the hermaphrodite stops making sperm and starts making oocytes. Temperature shift experiments also show that, in the germ line, sexual commitment appears to be a continuing process. Spermatogenesis can resume even after oogenesis has begun, and oogenesis can be initiated much later than normal
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Osbrink, Weste, i Lynn Carta. "Rhabditis rainai n. sp. (Nematoda: Rhabditida) associated with the Formosan subterranean termite, Coptotermes formosanus (Isoptera: Rhinotermitidae)". Nematology 7, nr 6 (2005): 863–79. http://dx.doi.org/10.1163/156854105776186299.
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AbstractRhabditis rainai n. sp. is described from the gut and head of sick Formosan subterranean termites (Coptotermes formosanus) collected in New Orleans, LA, USA (isolate LKC20). Rhabditis rainai n. sp. is a hermaphroditic species with an unusual prerectum, four denticles per glottoid swelling, enlarged posterior stoma, three paired lip sectors, protruding posterior anal lip, and five ridges in the hermaphrodite lateral field. Males generated from starved bacterial cultures have three lateral field ridges and a notched peloderan bursa with only eight rays. Male spicules are distinctive with a round but truncated head, constricted neck, narrow shoulders, nearly straight blade with distal tenth upturned, and rounded tips supporting a curved ventral arch. Males of LKC20 were mated successfully with hermaphrodites cultured from a Fiji Islands soil (isolate PS1191). In subsequent crosses, male progeny were fertile as expected for conspecific populations. Differences in morphometrics of cultured specimens that were heat-killed or fixed is demonstrated. Rhabditis rainai n. sp. was compared to R. blumi and R. adenobia, but does not fit clearly within the current subgenera of Rhabditis or genera of Rhabditidae. Nematode-termite relationships and possible origin of R. rainai n. sp. with Formosan subterranean termites from Southeast Asia are discussed.
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Sola, L., M. Marzovillo, A. R. Rossi, E. Gornung, S. Bressanello i B. J. Turner. "Cytogenetic analysis of a self-fertilizing fish, Rivulus marmoratus: remarkable chromosomal constancy over a vast geographic range". Genome 40, nr 6 (1.12.1997): 945–49. http://dx.doi.org/10.1139/g97-121.
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The aplocheiloid killifish Rivulus marmoratus is the only known self-fertilizing hermaphroditic vertebrate. Most natural populations consist almost entirely of hermaphrodites and comprise arrays of homozygous clones. However, in almost all populations thus far studied, clonal variation, as detected with molecular techniques, is very high. A karyological survey was carried out on specimens from Brazil, the Bahamas, Belize, and Florida (4 locales) by C-banding, silver staining, and fluorescent staining. The chromosome complement of R. marmoratus is surprisingly uniform over its vast geographic range, in terms of both chromosome number and morphology, heterochromatin distribution and composition, and nucleolar organizer region (NOR) distribution. The short arms of chromosome pair 15, where NORs are located, showed the only variation detected in this study: those of pattern A were consistently shorter than those of pattern B; moreover, the latter show positive heteropycnosis with Giemsa staining. The present data demonstrate that chromosomal variation is not a significant part of the clonal divergence in this species, even though its breeding system, by forming homozygotes for new rearrangements almost immediately, should make that variation easier to detect. The high chromosomal homogeneity is discussed in the light of the peculiar natural history of the species.Key words: hermaphrodite killifish, chromosomes, NORs, heterochromatin.
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Minniti, Alicia N., Cathryn Sadler i Samuel Ward. "Genetic and Molecular Analysis of spe-27, a Gene Required for Spermiogenesis in Caenorhabditis elegans Hermaphrodites". Genetics 143, nr 1 (1.05.1996): 213–23. http://dx.doi.org/10.1093/genetics/143.1.213.
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Abstract Hermaphrodites with mutations in the spe-27gene are self-sterile, laying only unfertilized eggs; mutant males are fertile. Hermaphrodites make spermatids that fail to activate to crawling spermatozoa so passing oocytes sweep them out of the spermatheca. These spermatids do activate and produce self-progeny if young mutant hermaphrodites are mated by fertile (or sterile) males. Spermatids isolated from either mutant males or hermaphrodites initiate activation in vitro when treated with proteases, but then arrest with spiky membrane projections that resemble those of a normal intermediate in pseudopod formation. These phenotypes are identical to spe-8 and spe-12 mutants. They can be explained if males and hermaphrodites have distinct pathways for spermatid activation, and these three genes are necessary only for the hermaphrodite pathway. Consistent with this model, when spe-27 mutant male spermatids without seminal fluid are artificially inseminated into hermaphrodites, they fail to activate. The spe-27 gene has been isolated, sequenced and its regulatory regions identified. The sequence predicts a 131 amino acid polypeptide that has no striking structural motifs and no resemblance to known proteins. Two of the mutations in spe-27alter mRNA splicing; a third mutation is a temperature-sensitive missense mutation.
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Penagos Zuluaga, Juan C., Simon A. Queenborough i Liza S. Comita. "Flowering sex ratios and costs of reproduction in gynodioecious Ocotea oblonga (Lauraceae)". Biological Journal of the Linnean Society 131, nr 2 (28.08.2020): 344–55. http://dx.doi.org/10.1093/biolinnean/blaa117.
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Abstract In gynodioecious plant species, both female and hermaphrodite individuals produce fruit, but only hermaphrodites produce pollen. Such sex-specific differences in reproductive investment may contribute to dimorphism, but the magnitude and ecological effects are still unclear, especially for gynodioecious tropical trees where collecting flowers and determining the sex is complex. We documented flowering and fruiting over three years in a natural population of Ocotea oblonga (Lauraceae) trees in a tropical moist forest, Panama. We determined sex from freshly collected flowers, counted and measured fruit, and used long-term growth data for each individual. We confirmed that O. oblonga is gynodioecious. No tree switched sex or had flowers of both sexes. The population was hermaphrodite-biased. We found no ecological differences in reproductive investment (seed, fruit, or tree size, or growth rate) between the sexes, indicating that the sex differential in the cost of reproduction is much smaller in woody gynodioecious taxa than in dioecious taxa. Females produced more fruit than hermaphrodites, which may contribute to their persistence in the population. Accordingly, and contrary to most studies of temperate gynodioecious populations, our study of a tropical tree shows no differential cost of reproduction in a hermaphrodite-biased population. Consequently, other factors such as seed fertility or herbivory could drive the biased sex ratio in this population.
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Popovic, Zorica, Milena Stefanovic, Miroslava Smiljanic, Rada Matic, M. Kostic, Vera Vidakovic i S. Bojovic. "Sex expression in Serbian dendroflora: A case study of Fraxinus ornus var. angustifolia". Archives of Biological Sciences 64, nr 1 (2012): 107–11. http://dx.doi.org/10.2298/abs1201107p.
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Out of a total number of tree species in Serbian flora, 28% are hermaphrodites, 43% are monoecious and 29% are dioecious. The dendroflora appears to have a larger proportion of unisexual than hermaphrodite species. The monoecious system is the dominant unisexual system within the tree species in Serbia. The possible sex differentiation by RAPD markers and Correspondence Analysis was examined in a population of Fraxinus ornus var. angustifolia. On the basis of 6 selected RAPD bands which contribute to the differentiation in frequency between male and hermaphrodite individuals, Correspondence Analysis visualized the following tendency: 20 trees of each variety were separated into two groups that mainly correspond to sexual types. Our results showed that RAPD markers assisted by Correspondence Analysis could be used in identifying male and hermaphrodite individuals in F. ornus varieties.
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Sakai, Satoki, Yuka Suzuki, Tomoyuki Itagaki, Hisashi Tsujisawa i Takashi T. Makino. "On the function of hermaphrodite florets in female inflorescences of Petasites japonicus (Asteraceae)". Botany 86, nr 2 (luty 2008): 179–84. http://dx.doi.org/10.1139/b07-121.
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To examine the function of morphologically hermaphroditic, but functionally sterile, florets in female inflorescences of Petasites japonicus (Sieb. & Zucc.) Maxim., we conducted experiments in which all those florets were removed from female inflorescences. We hypothesize that those florets enhance female reproductive success by deceit, because they resemble the morphologically hermaphroditic, but functionally male florets, in male inflorescences. We found that the mean number of pollinator visits per inflorescence did not differ between the intact inflorescences and inflorescences in which such hermaphrodite florets had been removed. However, the mean duration of stay per visit to an inflorescence tended to be shorter in those with removed florets than in the intact inflorescences. The achene / female floret ratio was smaller in the inflorescences with removed florets than in the intact ones. We hence concluded that the hermaphrodite florets in female inflorescences enhance female reproductive success through prolonged duration of pollinator stay.
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Maki, Masayuki. "Differences in plant size and flower production between hermaphrodites and females of two gynodioecious Chionographis (Liliaceae)". Canadian Journal of Botany 74, nr 1 (1.01.1996): 150–53. http://dx.doi.org/10.1139/b96-020.
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Plant size and flower production were compared between female and hermaphroditic plants of two gynodioecious Chionographis. Frequency distribution of size and minimum size class of flowering plants were not different between two sex morphs in both Chionographis. In C. japonica ssp. hisauchiana, females produced more ovuliferous flowers than hermaphrodites, although the total number of flowers were not significantly different between two sex morphs. In contrast, hermaphrodites of C. japonica var. kurohimensis exceeded females in the total number of flowers, whereas the number of ovuliferous flowers was not significantly different between two sex morphs. Reproductive effort at flowering season is not different between females and hermaphrodites. These little differences in secondary sex characters, compared with dioecious species, are probably due to the selfing of hermaphrodites and weaknesses in gender specialization. Keywords: Chionographis, flower production, gynodioecy, plant size, secondary sex characters.
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Fitch, Maureen M. M., Paul H. Moore, Terryl C. W. Leong, Leslie Ann Y. Akashi, Aileen K. F. Yeh, Susan A. White, Amy S. Dela Cruz, Lance T. Santo, Stephen A. Ferreira i Leslie J. Poland. "Clonally Propagated and Seed-derived Papaya Orchards: II. Yield Comparison". HortScience 40, nr 5 (sierpień 2005): 1291–97. http://dx.doi.org/10.21273/hortsci.40.5.1291.
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Gynodioecious papaya (Carica papaya L.) seedlings in commercial cropping systems in Hawaii are typically multiple-planted and thinned upon flowering to a single hermaphrodite because seedlings segregate for sex expression. Use of clonally propagated hermaphrodites would eliminate the over-planting practice and may provide other advantages. Yields of clonally propagated hermaphrodites were compared with single- and multiple-planted seedlings in three fields on two islands in Hawaii. Cloned hermaphrodites were either rooted cuttings or in vitro micropropagated plants. Clonally propagated plants bore ripe fruit 1 to 3 months earlier than thinned seedlings and had significantly higher early and cumulative yields. At each site, cumulative yields of thinned seedlings never reached the same level as those of clonally propagated plants. The yield benefit from clonally propagated plants was greatest at Keaau, the lowest sunlight and least productive test site.
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Li, Cheng-Yu, Shu-Ping Huang, Mark Garcia, Adam Fuller, Yuying Hsu i Ryan L. Earley. "Sexual phenotype drives variation in endocrine responses to social challenge in a quasi-clonal animal". Royal Society Open Science 5, nr 4 (kwiecień 2018): 180002. http://dx.doi.org/10.1098/rsos.180002.
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In many species, males tend to behave more aggressively than females and female aggression often occurs during particular life stages such as maternal defence of offspring. Though many studies have revealed differences in aggression between the sexes, few studies have compared the sexes in terms of their neuroendocrine responses to contest experience. We investigated sex differences in the endocrine response to social challenge using mangrove rivulus fish, Kryptolebias marmoratus . In this species, sex is determined environmentally, allowing us to produce males and hermaphrodites with identical genotypes. We hypothesized that males would show elevated androgen levels (testosterone and 11-ketotestosterone) following social challenge but that hermaphrodite responses might be constrained by having to maintain both testicular and ovarian tissue. To test this hypothesis, we staged fights between males and between hermaphrodites, and then compared contest behaviour and hormone responses between the sexes. Hermaphrodites had significantly higher oestradiol but lower 11-ketotestosterone than males before contests. Males took longer to initiate contests but tended to fight more aggressively and sustain longer fights than hermaphrodites. Males showed a dramatic post-fight increase in 11-ketotestosterone but hermaphrodites did not. Thus, despite being genetically identical, males and hermaphrodites exhibit dramatically different fighting strategies and endocrine responses to contests.
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Baeza, J. Antonio. "No effect of group size on sex allocation in a protandric-simultaneous hermaphroditic shrimp". Journal of the Marine Biological Association of the United Kingdom 87, nr 5 (październik 2007): 1169–74. http://dx.doi.org/10.1017/s0025315407057542.
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Lysmata wurdemanni is a protandric-simultaneous hermaphroditic shrimp. Individuals reproduce as males first and late in life as simultaneous hermaphrodites. I examined whether sex allocation (resources devoted to ova vs sperm) varies with group size in shrimps that have just matured as hermaphrodites. Focal males were reared with different numbers of hermaphrodites (1, 2, 5 or 10). Sperm stored in the ejaculatory ducts and eggs brooded underneath the abdomen were retrieved and weighted immediately after focal shrimps matured as hermaphrodites. Hermaphrodites should invest more into sperm with increasing group size to cope with more intense sperm competition. The proportion of focal shrimps that lost their first clutch of eggs after maturing as hermaphrodites increased with group size. This suggests male gender preferences by hermaphrodites experiencing large group sizes. No differences in sex allocation among group sizes were recorded for shrimps that did not lose their first clutch of eggs. Thus, group size does not affect sex allocation in terms of ova and sperm mass. This lack of phenotypic plasticity might be explained if sperm competition is not important in L. wurdemanni. It should not pay in terms of fitness for shrimps to produce and inseminate female-role hermaphrodites with large amounts of sperm when full paternity is assured in the absence of multi-male mating. In agreement with this idea, a second experiment demonstrated that female-role hermaphrodites invariably mated only once with a single other shrimp.
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Callejas-Chavero, Alicia, Carlos F. Vargas-Mendoza, Carlos Gomez-Hinostrosa, Victor J. Arriola-Padilla i Amelia Cornejo-Romero. "Breeding system in a population of the globose cactus Mammillaria magnimamma at Valle del Mezquital, Mexico". Botanical Sciences 99, nr 2 (14.02.2021): 229–41. http://dx.doi.org/10.17129/botsci.2654.
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Background: The breeding system of Mammillaria magnimamma was initially described as hermaphroditic. However, some individuals in a natural population at Valle del Mezquital exhibited a seemingly non-functional androecium.
Objectives: To determine the breeding system of M. magnimamma through morphological characterization of floral types.
Study site and years: The study was conducted at Valle del Mezquital, Mexico, during the 2019 reproductive season.
Methods: We characterized floral polymorphism by means of scanning electron microscopy and morphometric analysis of 18 floral traits. Pollinator frequency, size and number of seeds, and germination rate were compared between flower types.
Results: 87.85 % of the plants were hermaphrodites, and 12.15 % were females with non-functional androecium, with significantly smaller stamens, indehiscent anthers, and malformed pollen. Female flowers were shorter (14.007 ± 0.742 mm) and had smaller (1.856 ± 0.151 mm) nectar chambers than hermaphroditic flowers (15.821 ± 0.450 and 2.194 ± 0.090 mm, respectively). Although pollinators visited hermaphrodites (124 visits) about twice as often as pistillate flowers (60 visits), the latter produced more numerous (F1,26 = 8.320, P = 0.003) and larger (Hc = 4.637, P = 0.031) seeds that also germinated faster (Hc = 70.59, P < 0.0001).
Conclusions: This M. magnimamma population exhibits a gynodioecious breeding system with both hermaphroditic and male sterile female plants. Females produce more, higher quality seeds, which favour their maintenance in the population.
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Michiels, Nico K., Philip H. Crowley i Nils Anthes. "Accessory male investment can undermine the evolutionary stability of simultaneous hermaphroditism". Biology Letters 5, nr 5 (15.07.2009): 709–12. http://dx.doi.org/10.1098/rsbl.2009.0280.
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Sex allocation (SA) models are traditionally based on the implicit assumption that hermaphroditism must meet criteria that make it stable against transition to dioecy. This, however, puts serious constraints on the adaptive values that SA can attain. A transition to gonochorism may, however, be impossible in many systems and therefore realized SA in hermaphrodites may not be limited by conditions that guarantee stability against dioecy. We here relax these conditions and explore how sexual selection on male accessory investments (e.g. a penis) that offer a paternity benefit affects the evolutionary stable strategy SA in outcrossing, simultaneous hermaphrodites. Across much of the parameter space, our model predicts male allocations well above 50 per cent. These predictions can help to explain apparently ‘maladaptive’ hermaphrodite systems.
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Ganger, Mike, i Tiffany Sturey. "Antheridiogen concentration and spore size predict gametophyte size in Ceratopteris richardii". Botany 90, nr 3 (marzec 2012): 175–79. http://dx.doi.org/10.1139/b11-097.
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In many plants females invest more in reproduction than males. In organisms that exhibit environmental sex determination, individuals in low-quality environments or who are slow growing are expected to develop into males. The gametophytes of Ceratopteris richardii Brongn., a homosporous fern, may develop as males or hermaphrodites. Hermaphrodites secrete a pheromone called antheridiogen that induces undifferentiated spores to develop as males. Given that induction is not 100% in the presence of antheridiogen, it is hypothesized that resources may alter C. richardii gender decisions. An experiment was undertaken to determine (i) whether spore size predicts gender, (ii) whether spore size predicts gametophyte size, (iii) whether antheridiogen negatively affects the growth of C. richardii, and (iv) whether wild-type C. richardii and him1 mutants (genetic mutants disposed to male development regardless of antheridiogen presence) behave similarly in their response to antheridiogen. Spore size was not predictive of gender but was positively related to both male and hermaphrodite gametophyte size. Antheridiogen was found to slow the growth of male and hermaphrodite gametophytes of the wild type and male gametophytes of the him1 mutant. These results are supportive of the idea that gender may be determined indirectly through antheridiogen’s effect on gametophyte growth.
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Zetka, M. C., i A. M. Rose. "Sex-related differences in crossing over in Caenorhabditis elegans." Genetics 126, nr 2 (1.10.1990): 355–63. http://dx.doi.org/10.1093/genetics/126.2.355.
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Abstract In the nematode Caenorhabditis elegans, hermaphrodite recombination has been characterized and is the basis of the genetic map used in this organism. In this study we have examined male recombination on linkage group I and have found it to be approximately one-third less than that observed in the hermaphrodite. This decrease was interval-dependent and nonuniform. We observed less recombination in the male in 5 out of 6 intervals examined, and no observable difference in one interval on the right end of LG I. Hermaphrodite recombination frequencies are the result of recombination in two germlines; oocyte and hermaphrodite spermatocytes. We have measured recombination in the oocyte and have found it to be approximately twofold lower than that calculated for hermaphrodite spermatocytes and not significantly different from the male spermatocyte frequency. Thus, recombination frequencies appear to be a function of gonad physiology rather than the sex of the germline. Evidence from experiments examining the effect of karyotype on recombination in males sexually transformed by the her-1 mutation into XO hermaphrodites (normally XX), suggests the sexual phenotype rather than genotype determines the recombination frequency characteristic of a particular sex. Hermaphrodite recombination is known to be affected by temperature, maternal age, and the rec-1 mutation. We have examined the effect of these parameters on recombination in the male and have found male recombination frequency increased with elevated temperatures and in the presence of Rec-1, and decreased with paternal age.
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Rushforth, Alice M., Claudia Cummins White i Philip Anderson. "Functions of the Caenorhabditis elegans Regulatory Myosin Light Chain Genes mlc-1 and mlc-2". Genetics 150, nr 3 (1.11.1998): 1067–77. http://dx.doi.org/10.1093/genetics/150.3.1067.
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Abstract Caenorhabditis elegans contains two muscle regulatory myosin light chain genes, mlc-1 and mlc-2. To determine their in vivo roles, we identified deletions that eliminate each gene individually and both genes in combination. Functions of mlc-1 are redundant to those of mlc-2 in both body-wall and pharyngeal muscle. mlc-1(0) mutants are wild type, but mlc-1(0) mlc-2(0) double mutants arrest as incompletely elongated L1 larvae, having both pharyngeal and body-wall muscle defects. Transgenic copies of either mlc-1(+) or mlc-2(+) rescue all defects of mlc-1(0) mlc-2(0) double mutants. mlc-2 is redundant to mlc-1 in body-wall muscle, but mlc-2 performs a nearly essential role in the pharynx. Approximately 90% of mlc-2(0) hermaphrodites arrest as L1 larvae due to pharyngeal muscle defects. Lethality of mlc-2(0) mutants is sex specific, with mlc-2(0) males being essentially wild type. Four observations suggest that hermaphrodite-specific lethality of mlc-2(0) mutants results from insufficient expression of the X-linked mlc-1(+) gene in the pharynx. First, mlc-1(0) mlc-2(0) double mutants are fully penetrant L1 lethals in both hermaphrodites and males. Second, in situ localization of mlc mRNAs demonstrates that both mlc-1 and mlc-2 are expressed in the pharynx. Third, transgenic copies of either mlc-1(+) or mlc-2(+) rescue the pharyngeal defects of mlc-1(0) mlc-2(0) hermaphrodites. Fourth, a mutation of the dosage compensation gene sdc-3 suppresses hermaphrodite-specific lethality of mlc-2(0) mutants.
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Jones, Andrew, i Martin Burd. "Vegetative and reproductive variation among unisexual and hermaphroditic individuals of Wurmbea dioica (Colchicaceae)". Australian Journal of Botany 49, nr 5 (2001): 603. http://dx.doi.org/10.1071/bt01008.
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Hermaphroditism may constrain the effects of sex-specific selection on life history and reproductive traits. Wurmbea dioica in south-eastern Australia has populations with male, female and hermaphroditic plants, allowing an intraspecific comparison from which inferences may be made about the nature of evolutionary specialisation for each sexual function. We found that pistillate plants of W. dioica in a population in central Victoria were larger than male plants, but that males produced more and larger flowers. When comparing whole-plant means, males did not differ from hermaphrodites in pollen investment and females did not differ from hermaphrodites in fruit mass. However, when data for individual flowers were analysed with a statistical control for floral size, flowers of hermaphrodites had less investment in both pollen and fruit compared with flowers of the corresponding unisexual plants, implying that an intra-floral allocation trade-off occurs. Investment per flower in pollen had no apparent trade-off with flower number per plant, while fruit investment did show a significant relationship to flower number per plant, but the relationship was in different directions for females and hermaphrodites. Sex-specific selection has apparently favoured differentiation of investment strategies for males and females, while hermaphrodites reveal some morphological compromises that must be made to engage in both sexual functions.