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Male Phenotype (male + phenotype)
Selected AbstractsFEMALE SOLDIER BEETLES DISPLAY A FLEXIBLE PREFERENCE FOR SELECTIVELY FAVORED MALE PHENOTYPESEVOLUTION, Issue 5 2005Denson Kelly Mclain Abstract In Georgia (USA) the soldier beetle, Chauliognathus pennsylvanicus (Coleoptera; Cantharidae), exhibits clinal variation in the length of the spot on its elytron. This suggests that the viability of phenotypes varies by habitat. Evidence of viability selection comes from within-site changes in the spot length distribution across a breeding season. When males with spots of intermediate length became less frequent, they became disproportionately less likely to mate, consistent with either a loss of vigor among remaining males or female rejection of disfavored phenotypes. Persistent, daily courtship by males provides females with the opportunity to track changes in male phenotype frequency and to exercise choice for phenotypes favored under natural selection. A laboratory experiment in which the frequency of one spot morph (long) or the other (short) was increased from 25% to 75% over a period of 30 days revealed that females possess a flexible preference that leads them to prefer whichever spot type has become more common over time. A haploid genetic model demonstrates that a flexible female preference for the locally favored male phenotype can be selected for when different viability alleles, genetically correlated with the male trait, are favored in different habitats that are linked by gene flow. Thus, migration between different kinds of habitat patches of a metapopulation could maintain the variation in male quality. This variation favors female choice for any trait that is directly or indirectly favored by natural selection. Such choice imparts positive frequency-dependent selection that could rapidly fix traits pleiotropically linked to viability. Rapid fixation would cause differentiation between populations of colonizing species as females exercise choice for mates favored under new ecological conditions. [source] SEXUAL SELECTION AND THE EVOLUTION OF COSTLY FEMALE PREFERENCES: SPATIAL EFFECTSEVOLUTION, Issue 3 2000Troy Day Abstract., Models of Fisher's runaway process show that if there is a cost to female preference, no preference or male trait exaggeration will evolve. Surprisingly, this is true no matter how small the cost, which reveals that these models of Fisher's process are structurally unstable (Bulmer 1989). Here a model of Fisher's runaway process is presented to demonstrate that costly female preference evolves very easily when space is explicitly included in the model. The only requirement is that the optimal male phenotype changes across the species' range. The model shows that the spatial average of the female preference and male trait reach an evolutionary equilibrium that is identical to those of nonspatial models, but that the preference and male trait can deviate greatly from these averages at any point in space. For example, if random mating results in the lowest cost to females, then at equilibrium the spatial average preference will be zero. Nevertheless, there will be some locations at which females prefer males with larger ornaments and others where they prefer males with smaller ornaments. Results also show that the structural instability of nonspatial models of Fisher's process is less of a problem in spatial models. In particular, many of the main qualitative features of cost-free spatial models of Fisher's process remain valid even when there are small costs of female preference. Finally, the model shows that abrupt changes in the optimal male phenotype across space can result in an amplification of this pattern when preference has a small cost, but it can also result in a pattern similar to reproductive character displacement. Which of these occurs depends on the magnitude of the cost of female preference. This suggests that some patterns of reproductive character displacement in nature might be explained simply by sexual selection rather than by hybrid dysgenesis and reinforcement. [source] Transplanted XY germ cells produce spermatozoa in testes of XXY mice,INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 4 2010Y. Lue Summary XXY mouse has been characterized as an experimental model for men with Klinefelter's syndrome (XXY male phenotype). To test whether donor XY germ cells could proliferate and differentiate in the XXY testicular environment, donor testicular cells from adult (2,3 months old) and immature (10 days old) XY green fluorescence protein (GFP) transgenic mice were transplanted into the seminiferous tubules of adult (4,7 months old) and young (6 weeks old) XXY recipient mice respectively. Twelve weeks after transplantation, GFP positive spermatogonia were found in 21.74% (five out of 23) of adult XXY recipients who received adult donor cells. The GFP positive segments of seminiferous tubules were observed in 44.44% (four out of nine) young XXY recipients who received donor cells from 10 days old GFP mice. We found using immunohistochemistry and cell morphology that donor-derived GFP positive germ cells were spermatogonia, spermatocytes, round spermatids and spermatozoa in some of the seminiferous tubules of young XXY recipient mice. The results demonstrated that the donor XY germ cells were able to qualitatively complete spermatogenesis in some of the seminiferous tubules of XXY mice. [source] Initiation of Steroidogenesis Precedes Expression of Cholesterologenic Enzymes in the Fetal Mouse TestesANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2009T. Büdefeld Summary Sexual differentiation is a carefully regulated process that ultimately results in a development of the male or female phenotype. Proper development of the male phenotype is dependent upon the action of testosterone and anti-mullerian hormone. Leydig cells start to produce testosterone around day 12.5 in the fetal mouse testis, and continue to produce high levels of this hormone throughout gestation. In the present study, we examined whether expression of lanosterol 14,-demethylase (cyp51) and cytochrome P450 NADPH reductase, both involved in the cholesterol production, occurs simultaneously with proteins required for the production of steroid hormones. Immunocytochemical staining with the antibodies against cyp51, cytochrome P450 NADPH reductase, steroidogenic acute regulatory protein (StAR) and 3beta-hydroxysteroid dehydrogenase I (3,-HSD I) was used to determine the ontogeny of expression of these four proteins. As expected, 3,-HSD I and StAR proteins were detected on day 12.5 p.c., while expression of cyp51 and NADPH cytochrome P450 reductase appeared 1 day later, on day 13.5. Thereafter, the expression of all four proteins remained strong throughout gestation. Results of this study suggest that initial steps of steroid hormone production in murine Leydig cells are mostly dependent on exogenously derived cholesterol, while from day 13.5 onwards, mouse Leydig cells are able to synthesize cholesterol and are therefore not dependent on exogenous cholesterol resources. [source] Ovotesticular disorder of sex development with a prostatic gland and review of literatureANDROLOGIA, Issue 6 2009H. C. Irkilata Summary Ovotesticular disorder of sex development (OTDSD) is a rare condition and defined as the presence of ovarian and testicular tissue in the same individual. Most of patients with OTDSD have female internal genital organs. In this report, we present a case in which, we demonstrated prostate tissue using endoscopic and radiologic methods in a 46-XX, sex determining region of the Y chromosome negative male phenotypic patient, with no female internal genitalia. Existence of prostate in an XX male without SRY is rarely seen and reveals a complete male phenotype. This finding is critical to figure out what happens in embryonal period. [source] SEXUAL CONFLICT AND CRYPTIC FEMALE CHOICE IN THE BLACK FIELD CRICKET, TELEOGRYLLUS COMMODUSEVOLUTION, Issue 4 2006Luc F. Bussiégre Abstract The prevalence and evolutionary consequences of cryptic female choice (CFC) remain highly controversial, not least because the processes underlying its expression are often concealed within the female reproductive tract. However, even when female discrimination is relatively easy to observe, as in numerous insect species with externally attached spermatophores, it is often difficult to demonstrate directional CFC for certain male phenotypes over others. Using a biological assay to separate male crickets into attractive or unattractive categories, we demonstrate that females strongly discriminate against unattractive males by removing their spermatophores before insemination can be completed. This results in significantly more sperm being transferred by attractive males than unattractive males. Males respond to CFC by mate guarding females after copulation, which increases the spermatophore retention of both attractive and unattractive males. Interestingly, unattractive males who suffered earlier interruption of sperm transfer benefited more from mate guarding, and they guarded females more vigilantly than attractive males. Our results suggest that postcopulatory mate guarding has evolved via sexual conflict over insemination times rather than through genetic benefits of biasing paternity toward vigorous males, as has been previously suggested. [source] | |||||||||||||