Sperm-Female Coevolution: Mechanisms, Models & Theoretical Implications

点击翻译按钮获取中文摘要

Sperm-female coevolution: mechanisms, models and theoretical implications.Recent work has demonstrated that the shapes of sperm and of the femalereproductive tract evolve in concert. This pattern is attributable to aprocess known as female "sperm choice," with female reproductivetract characteristics producing a bias in patterns of paternity whenfemales mate with multiple males, such as biasing fertilization in favor oflonger sperm. Research proposed here will investigate (1) physiologicalmechanisms of female sperm choice, (2) possible benefits tofemales of having the ability to "discriminate" among sperm variants, (3)costs and benefits to males of variation in traits that contribute tofertilization success, and (4) implications of producing few,large sperm for sex difference theory.Disparity between the sexes in the size of their sex cells is believed tobe the cornerstone of all sex differences (e.g., body size, aggressiveness,ornamentation). However, contrary to popular belief, males of all speciesdo not produce many tiny sperm. In fact, sperm cells are the most diversecell type: in nearly all animal groups, they evolve in size, shape, andstructure so rapidly that even closely related species can usually bediscriminated by their sperm. Because having the correct species-specificsperm structure is pivotal for successful reproduction, sperm divergencemay function as an "engine of speciation." Understanding the causes ofsperm evolution is thus important to our understanding of the biologicalbasis of sex differences and of the process of speciation.