RUI: Variation in the Dispersal of Fertilizing Sperm as a Function of Population Density

我寻求资金，以探索种群密度的变化对受精精子(那些成功使卵子受精的精子，而不是所有被释放的精子)的扩散距离以及殖民地海囊中多重父子关系的发生率的影响。到目前为止的工作已经证明：1)野外精子密度随着与隔离雄性的距离而迅速下降。2)卵子受精率是精子密度的函数。这些初步数据表明，当多个男性参与受精时，受精精子的传播距离将比之前报道的孤立男性的距离短得多。如果一个雄性受精卵子的概率与其精子相对于其他雄性受精的密度成正比，那么受精精子的分散距离将随着种群密度的增加而减小。因此，在较高的种群密度下，可能会有更多的雄性参与每一只雌性的受精，导致一窝幼虫中的多重父子关系的增加。我建议通过建立具有不同密度的已知遗传标记的海鞘种群来检验这些假设，并进行父子关系分析，以在受精后分析孵化幼虫的父子关系。这项研究将通过研究种群密度的变化对种群结构的各个方面的影响，如杂交种群规模、近亲交配水平、邻近个体或群体的亲缘关系以及亚种群之间的基因流动，从而有助于我们对底栖海洋生物的了解。

I seek funding to explore the impact of variation in population density on the dispersal distance of fertilizing sperm (those sperm that successfully fertilize an egg, as opposed to all of the sperm that are released) and the incidence of multiple paternity in a colonial ascidian. Work to date has demonstrated that: 1) Sperm concentration in the field decreases rapidly with distance from isolated males. 2) The fertilization rate of eggs is a function of sperm concentration. These preliminary data suggest that the dispersal distance of fertilizing sperm when multiple males are contributing to fertilization will be much shorter than the distances previously reported for isolated males. If the probability of a given male fertilizing an egg is proportional to the concentration of his sperm relative to that of other males, then the dispersal distance of fertilizing sperm will decrease as population density increases. As a consequence, more males may participate in the fertilization of each female at higher population densities, leading to an increase in multiple paternity within a brood of larvae. I propose to test these hypotheses by establishing populations of ascidians with known genetic markers at different densities and conducting paternity analyses to assay the paternity of brooded larvae after fertilization has occurred. This study will contribute to our knowledge of benthic marine organisms by examining the potential for variation in population density to impact aspects of population structure such as interbreeding population size, levels of inbreeding, relatedness of neighboring individuals or colonies, and gene flow among sub- populations.