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

我寻求资金来探索种群密度变化对受精卵（那些成功与卵子受精的精子，而不是所有被释放的精子）扩散距离的影响，以及海鞘种群中多父性的发生率。迄今为止的研究表明：1)野外的精子浓度随着与孤立雄性的距离而迅速下降。2)卵子受精率是精子浓度的函数。这些初步数据表明，当多个雄性参与受精时，受精精子的传播距离将比以前报道的孤立雄性的传播距离短得多。如果一个给定的雄性使卵子受精的概率与他的精子相对于其他雄性的浓度成正比，那么受精精子的分散距离将随着种群密度的增加而减少。因此，在较高的种群密度下，可能会有更多的雄性参与每只雌性的受精，从而导致一窝幼虫中多父性的增加。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，并进行父权分析，以测定受精后孵化的幼虫的父权，来验证这些假设。本研究将通过研究种群密度变化对种群结构方面的潜在影响，如杂交种群规模、近亲繁殖水平、邻近个体或群体的亲缘关系以及亚种群之间的基因流动，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.