Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095-1606, USA.
Ecology. 2009 Dec;90(12):3478-88. doi: 10.1890/08-1732.1.
Replenishment of many marine populations occurs through the entry of juveniles to adult populations following a pelagic larval stage. Because mortality during the pelagic stage is thought to be high and density independent, larval abundance and traits of individual larvae should have strong effects on overall population dynamics in marine organisms. Surprisingly, few experiments have tested how localized interactions among breeding adults affect the quantity and phenotypic traits of larvae they produce. Here I experimentally test for the influence of food competition, mate limitation, and population density on somatic growth, fecundity, and offspring provisioning (larval length and energy reserves) in a planktivorous, territorial coral reef damselfish, Stegastes partitus. I manipulated food supply and adult S. partitus density on isolated patch reefs in the Bahamas and also made behavioral observations of S. partitus occurring on nearby natural reefs at a range of population densities. On the experimental reefs, females experienced density-dependent growth and fecundity; male reproductive success was density dependent, but male growth was not. Density-dependent growth and reproduction were not moderated by food supplementation, and density-dependent reproduction was not influenced by mate availability. On natural reefs, the frequency of aggressive interactions, particularly involving females, increased with population density, implicating aggression-related energetic costs as the source of both forms of density dependence in the experiments. Food supplementation increased female somatic growth and larval energy reserves, suggesting that females allocated surplus energy to future reproductive potential and enhanced offspring quality. Neither experimental treatment affected larval length. By altering patterns of reproduction, the interplay between spatial variation in food availability and population density may drive population dynamics in a broad range of benthic marine organisms.
许多海洋种群的补充是通过浮游幼体进入成体种群来实现的，这些幼体经历了浮游幼虫阶段。由于浮游阶段的死亡率高且与密度无关，因此幼虫的丰度和个体幼虫的特征应该对海洋生物的总体种群动态产生强烈影响。令人惊讶的是，很少有实验测试过繁殖成体之间的局部相互作用如何影响它们产生的幼虫的数量和表型特征。在这里，我通过实验测试了食物竞争、配偶限制和种群密度对食浮游生物的有领地性的珊瑚礁雀鲷 Stegastes partitus 的体生长、繁殖力和后代供应（幼虫长度和能量储备）的影响。我在巴哈马的孤立的斑块礁上操纵了食物供应和 S. partitus 成体的密度，并且还在一系列种群密度的附近的天然礁上对 S. partitus 的行为进行了观察。在实验礁上，雌性经历了与密度相关的生长和繁殖；雄性的繁殖成功率与密度有关，但雄性的生长不受密度影响。食物补充并没有调节密度依赖性的生长和繁殖，而配偶的可用性也没有影响密度依赖性的繁殖。在天然礁上，攻击性相互作用的频率（特别是雌性之间的相互作用）随着种群密度的增加而增加，这表明与侵略有关的能量成本是实验中两种密度依赖性的来源。食物补充增加了雌性的体生长和幼虫的能量储备，这表明雌性将多余的能量分配给未来的生殖潜力，并提高了后代的质量。实验处理都没有影响幼虫的长度。通过改变食物供应的空间变化模式和种群密度的相互作用，可能会驱动广泛的底栖海洋生物的种群动态。
