Hanley Torrance C, Hughes A Randall, Williams Bethany, Garland Hanna, Kimbro David L
Ecology. 2016 Jun;97(6):1518-29. doi: 10.1890/15-1710.1.
Intraspecific diversity, particularly of foundation species, can significantly affect population, community, and ecosystem processes. Examining how genetic diversity relates to demographic traits provides a key mechanistic link from genotypic and phenotypic variation of taxa with complex life histories to their population dynamics. We conducted a field experiment to assess how two metrics of intraspecific diversity (cohort diversity, the number of independent juvenile cohorts created from different adult source populations, and genetic relatedness, genetic similarity among individuals within and across cohorts) affect the survivorship, growth, and recruitment of the foundation species Crassostrea virginica. To assess the effects of both cohort diversity and genetic relatedness on oyster demographic traits under different environmental conditions, we manipulated juvenile oyster diversity and predator exposure (presence/absence of a cage) at two sites differing in resource availability and predation intensity. Differences in predation pressure between sites overwhelmingly determined post-settlement survivorship of oysters. However, in the absence of predation (i.e., cage treatment), one or both metrics of intraspecific diversity, in addition to site, influenced long-term survivorship, growth, and recruitment. While both cohort diversity and genetic relatedness were negatively associated with long-term survivorship, genetic relatedness alone showed a positive association with growth and cohort diversity alone showed a positive association with recruitment. Thus, our results demonstrate that in the absence of predation, intraspecific diversity can affect multiple demographic traits of a foundation species, but the relative importance of these effects depends on the environmental context. Moreover, the magnitude and direction of these effects vary depending on the diversity metric, cohort diversity or genetic relatedness, suggesting that although they are inversely related in this system, each captures sufficiently different components of intraspecific diversity. Given the global loss of oyster reef habitat and rapid decline in oyster population size, our results are particularly relevant to management and restoration. In addition, aquaculture, which commonly excludes predators during early life history stages, may benefit from incorporation of oyster cohort diversity into standard practice.
种内多样性，尤其是基础物种的种内多样性，会显著影响种群、群落和生态系统过程。研究遗传多样性与种群统计学特征之间的关系，为连接具有复杂生活史的分类单元的基因型和表型变异与其种群动态提供了关键的机制联系。我们进行了一项田间实验，以评估种内多样性的两个指标（群体多样性，即由不同成年源种群产生的独立幼体群体数量，以及遗传相关性，即群体内和群体间个体的遗传相似性）如何影响基础物种弗吉尼亚牡蛎的存活率、生长和补充。为了评估群体多样性和遗传相关性在不同环境条件下对牡蛎种群统计学特征的影响，我们在资源可用性和捕食强度不同的两个地点，对幼体牡蛎多样性和捕食者暴露情况（有无笼子）进行了操控。地点之间捕食压力的差异极大地决定了牡蛎定居后的存活率。然而，在没有捕食的情况下（即笼子处理），除了地点之外，种内多样性的一个或两个指标会影响长期存活率、生长和补充。虽然群体多样性和遗传相关性都与长期存活率呈负相关，但仅遗传相关性与生长呈正相关，仅群体多样性与补充呈正相关。因此，我们的结果表明，在没有捕食的情况下，种内多样性会影响基础物种的多个种群统计学特征，但这些影响的相对重要性取决于环境背景。此外，这些影响的大小和方向因多样性指标（群体多样性或遗传相关性）而异，这表明尽管它们在这个系统中呈负相关，但每个指标都捕捉到了种内多样性足够不同的组成部分。鉴于全球牡蛎礁栖息地的丧失和牡蛎种群数量的迅速下降，我们的结果与管理和恢复特别相关。此外，水产养殖通常在早期生活史阶段排除捕食者，将牡蛎群体多样性纳入标准做法可能会从中受益。
