نتایج جستجو برای: sperm traits
تعداد نتایج: 134527 فیلتر نتایج به سال:
Context Reproduction is an economically important trait in both males and females; however, the relationships between fertility body composition traits are little researched, but essential to breeding programs, as they will help inform selection decisions allow greatest opportunity for genetic gain. Aims Estimate phenotypic correlations male female yearling investigate their relationship with t...
Sperm competition, whereby sperm from multiple males compete to fertilize an egg, selects for adaptations that increase fertilization success. Because fertilization success is related to sperm number, size, and quality, both interspecific and intraspecific variation in these traits are predicted to correlate with the level of sperm competition. Specifically, species and individuals that experie...
Sperm senescence can have important evolutionary implications due to its deleterious effects on sperm quality and offspring performance. Consequently, it has been argued that polyandry (female multiple mating) may facilitate the selection of younger, and therefore competitively superior, sperm when ejaculates from multiple males compete for fertilization. Surprisingly, however, unequivocal evid...
Polyandry, where females mate with multiple males, means that a male's reproductive success will depend both on his ability to acquire mates and the ability of his sperm to compete effectively for fertilizations. But, how do males partition their reproductive investment between these two episodes of selection? Theory predicts that increases in ejaculate investment will come at a cost to investm...
In promiscuous species, male reproductive success depends on their ability to mate with fertile females and on the fertilizing ability of their sperm. In such species, theory predicts that, owing to a trade-off between pre- and post-copulatory reproductive traits, males with lesser access to females should increase resource investment into those sperm traits that enhance fertilization success-u...
Production of more than one morphological type of sperm in a common testis has been documented for a variety of invertebrates, including gastropods, spiders, centipedes, and insects. This unusual phenomenon is difficult to explain by current theory, particularly since available evidence indicates that one sperm type is often incapable of effecting fertilization. In this review we critically exa...
There is a notion in evolution that traits, once lost, cannot re-evolve. A new species of bone-eating worm defies this notion. Its males are free-living and look nothing like the dwarfed bags of sperm of its relatives.
Males of many species assess the likely level of sperm competition and respond adaptively, for example by increasing the level of courtship they deliver, by transferring more sperm or seminal fluids or by extending matings. In mechanistic terms, it may be easier for males to adjust the level of their investment to the likely level of sperm competition for male-limited traits such as sperm and s...
Sperm are a simple cell type with few components, yet they exhibit tremendous between-species morphological variation in those components thought to reflect selection in different fertilization environments. However, within a species, sperm components are expected to be selected to be functionally integrated for optimal fertilization of eggs. Here, we take advantage of within-species variation ...
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