Determinants of Male Reproductive Success in the Marine Hydrozoan Hydractinia Milleri

生殖成功和生活史演变的理论和实证研究主要集中在对女性表现的调节上。只有当可以假设男性生殖成功的决定因素与规范女性生殖成功的决定因素相同时，这种强调才是合理的。然而，在几乎所有的多细胞生物体中，生殖行为都有很大的性别差异，这导致了男性和女性生殖成功的决定因素的根本差异。生殖行为中最简单和最广泛的性别差异之一是雌配子保留在亲本体内直到受精后的一段时间，以及雄配子的传播(或由传粉者转移到空气或水中)。这种生殖二分法潜在地提高了(1)雄配子竞争，(2)受精前生殖成功的性别差异，以及(3)兄弟姐妹关系中父子关系的多样性的水平。因此，这种特定于性别的生殖模式变异可能会影响性别选择的强度、基因流的水平、繁殖系统的结构以及社会行为的演变。目前，对于任何非活动的水生无脊椎动物来说，关于雄性与雌性生殖成功的决定因素几乎一无所知。这项研究将对群居的水生动物水生动物--水母水母的个体繁殖成功和扩散情况进行直接的现场测量。DNA序列分析(即DNA指纹)，以确定孵化的幼虫和成虫的亲子关系，这些幼虫和成虫是绘制的种群的成员，并在三年期间招募到这些种群中。从野外和实验室操作相结合获得的数据将允许评估种群密度、大小和邻近程度如何影响生殖投资、受精成功和生殖成功之间的关系。

Theoretical and empirical studies of reproductive success and life-history evolution primarily focus on the regulation of female performance. This emphasis is justifiable only if it can be assumed that the determinants of male reproductive success are like those regulating female reproductive success. Yet, in virtually all multicellular organisms, there is substantial gender-specific variation in reproductive behavior, which leads to fundamental differences in the determinants of male and female reproductive success. One of the simplest and most phyletically widespread gender-specific differences in reproductive behavior is the retention of female gametes within the parent until some time after fertilization, and the broadcasting (or transfer by pollinators) of male gametes into air or water. This reproductive dichotomy potentially enhances levels of (1) intermale gametic competition, (2) gender-specific variance in pre-fertilization reproductive success, and (3) diversity of paternity within sibling relationships. Consequently, this sort of gender-specific variation in reproductive pattern potentially affects the intensity of sexual selection levels of gene flow, the structure of breeding systems, and the evolution of social behaviors. At present, virtually nothing is known about the determinants of male versus female reproductive success for any non-motile, aquatic invertebrate. This research will make direct field measurements of individual male (and, necessarily, female) reproductive success and dispersal in the colonial hydrozoan, Hydractinia milleri. DNA sequence analysis (i.e., DNA fingerprinting) to determine parent-offspring relationships of brooded larvae and adults that are members of, and recruit into, mapped populations over a three-year period. Data obtained from a combination of field and laboratory manipulations will allow an assessment of how colony density, size and proximity affect the relationship among reproductive investment, fertilization success, and reproductive success.