Sperm-Female Coevolution: Mechanisms, Models & Theoretical Implications

精子-雌性共同进化：机制，模型和理论意义。最近的工作表明，精子和女性生殖道的形状一致进化。 这种模式是由一种被称为雌性“精子选择”的过程造成的，当雌性与多个雄性交配时，雌性生殖道的特征会产生一种偏向性的父系模式，比如偏向于长精子的受精。 本文提出的研究将调查（1）女性精子选择的生理机制，（2）女性有能力“区分”精子变体的可能好处，（3）有助于受精成功的性状变异对男性的成本和利益，以及（4）产生很少的影响，性别差异理论的大精子。两性之间性细胞大小的差异被认为是所有性别差异的基石（例如，体型、攻击性、顺从性）。 然而，与普遍的看法相反，所有物种的雄性都不会产生很多微小的精子。 事实上，精细胞是最多样化的细胞类型：几乎在所有动物群体中，它们在大小、形状和结构上进化得如此之快，以至于即使是关系密切的物种通常也能通过它们的精子来区分。 因为拥有正确的物种特异性精子结构是成功繁殖的关键，精子分化可能起到“物种形成引擎”的作用。“因此，了解精子进化的原因对我们理解性别差异的生物学基础和物种形成过程很重要。

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.