Sperm Selection
Mostrando 13-24 de 62 artigos, teses e dissertações.
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13. PopulaÃÃo bacteriana, motilidade espermÃtica e fertilidade de sÃmen de piracanjuba Brycon orbignyanus, submetido ao resfriamento. / Bacterian population, sperm motility and fertility of piracanjuba semen Brycon orbignyanus (VALENCIENNES, 1849) under refrigeration.
Piracanjuba, Brycon orbignyanus, is a migratory fish species originated from the Grande River basin. Piracanjuba is currently an endangered species. As this species does not breed naturally in captivity, artificial fertilization is necessary. The aim of this study was to improve the protocols for piracanjuba semen refrigeration at 4-6Â C by pH standardizati
Publicado em: 2006
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14. Males' evolutionary responses to experimental removal of sexual selection.
We evaluated the influence of pre- and post-copulatory sexual selection upon male reproductive traits in a naturally promiscuous species, Drosophila melanogaster. Sexual selection was removed in two replicate populations through enforced monogamous mating with random mate assignment or retained in polyandrous controls. Monogamous mating eliminates all opport
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15. Positive selection on protein-length in the evolution of a primate sperm ion channel
Positive Darwinian selection on advantageous point substitutions has been demonstrated in many genes. We here provide empirical evidence, for the first time, that positive selection can also act on insertion/deletion (indel) substitutions in the evolution of a protein. CATSPER1 is a voltage-gated calcium channel found exclusively in the plasma membrane of th
National Academy of Sciences.
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16. All males are not created equal: Fertility differences depend on gamete recognition polymorphisms in sea urchins
Behaviors, morphologies, and genetic loci directly involved in reproduction have been increasingly shown to be polymorphic within populations. Explaining how such variants are maintained by selection is crucial to understanding the genetic basis of fertility differences, but direct tests of how alleles at reproductive loci affect fertility are rare. In the s
The National Academy of Sciences.
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17. Postcopulatory sexual selection in an arctiid moth (Utetheisa ornatrix).
The offspring of twice-mated female Utetheisa ornatrix show low incidence of mixed paternity. Most progeny are sired exclusively by one male, the larger one, irrespective of parental age, male pyrrolizidine alkaloid content, mating order, between-mating interval, or duration of copulation. Data are presented suggesting that the female herself may exert contr
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18. Positive selection in the egg receptor for abalone sperm lysin
The mechanism of speciation is a central problem in evolutionary biology. In free-spawning animals with no complex mating behavior, prezygotic reproductive isolation (speciation) could result from the rapid divergence of genes coding for sperm and egg proteins that bind each other during fertilization. In abalone, sperm lysin evolves rapidly by positive Darw
The National Academy of Sciences.
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19. Positive Darwinian selection drives the evolution of several female reproductive proteins in mammals
Rapid evolution driven by positive Darwinian selection is a recurrent theme in male reproductive protein evolution. In contrast, positive selection has never been demonstrated for female reproductive proteins. Here, we perform phylogeny-based tests on three female mammalian fertilization proteins and demonstrate positive selection promoting their diverg
The National Academy of Sciences.
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20. Virility Deficiency and the Sex-Ratio Trait in DROSOPHILA PSEUDOOBSCURA. I. Sperm Displacement and Sexual Selection
The Sex-Ratio (SR) phenomenon is associated with the X chromosome of many species of Drosophila. Males carrying SR transmit predominantly sperm bearing the X chromosome. SR, therefore, has a very significant advantage in segregation. This paper provides an experimental analysis of the role of virility selection in preventing the fixation of SR. SR males are
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21. Sexual selection, germline mutation rate and sperm competition
BioMed Central.
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22. Polymorphism in Genes That Influence Sperm Displacement
Paternity of offspring of multiply inseminated females is in many organisms highly skewed, with an advantage generally going to the male that most recently mated. Variation in sperm competitive ability can result in strong natural selection, and one expects that a gene that offers an advantage in sperm displacement would, all else being equal, be rapidly fix
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23. Meiotic drive alters sperm competitive ability in stalk-eyed flies.
Meiotic drive results when sperm carrying a driving chromosome preferentially survive development. Meiotic drive should therefore influence sperm competition because drive males produce fewer sperm than non-drive males. Whether meiotic drive also influences the competitive ability of sperm after ejaculation is unknown. Here we report the results from recipro
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24. Simultaneous hermaphroditism and sexual selection
Theory about the evolution of sexual behavior in dioecious species is based on the general assumption that egg production is limited by a female's ability to garner resources to make eggs, not by a lack of sperm to fertilize them. Reproductive success for males is thus limited by access to females (and their eggs). I suggest that egg production by simultaneo