Department of Environmental Science and Policy, University of California, Davis, CA 95616;
Smithsonian Environmental Research Center, Edgewater, MD 21037.
Proc Natl Acad Sci U S A. 2021 Mar 23;118(12). doi: 10.1073/pnas.2003955118.
As biological invasions continue to increase globally, eradication programs have been undertaken at significant cost, often without consideration of relevant ecological theory. Theoretical fisheries models have shown that harvest can actually increase the equilibrium size of a population, and uncontrolled studies and anecdotal reports have documented population increases in response to invasive species removal (akin to fisheries harvest). Both findings may be driven by high levels of juvenile survival associated with low adult abundance, often referred to as overcompensation. Here we show that in a coastal marine ecosystem, an eradication program resulted in stage-specific overcompensation and a 30-fold, single-year increase in the population of an introduced predator. Data collected concurrently from four adjacent regional bays without eradication efforts showed no similar population increase, indicating a local and not a regional increase. Specifically, the eradication program had inadvertently reduced the control of recruitment by adults via cannibalism, thereby facilitating the population explosion. Mesocosm experiments confirmed that adult cannibalism of recruits was size-dependent and could control recruitment. Genomic data show substantial isolation of this population and implicate internal population dynamics for the increase, rather than recruitment from other locations. More broadly, this controlled experimental demonstration of stage-specific overcompensation in an aquatic system provides an important cautionary message for eradication efforts of species with limited connectivity and similar life histories.
随着生物入侵在全球范围内的持续增加，已经投入了大量成本来实施根除计划，但往往没有考虑到相关的生态理论。理论渔业模型表明，捕捞实际上可以增加种群的平衡规模，而且未经控制的研究和传闻报告记录了由于入侵物种的移除（类似于渔业捕捞）而导致的种群增加。这两个发现都可能是由于高水平的幼体存活率与低成体丰度相关所致，通常称为过补偿。在这里，我们表明，在沿海海洋生态系统中，一项根除计划导致了特定阶段的过补偿，以及引入的捕食者种群在一年内增加了 30 倍。从没有根除工作的四个相邻区域海湾同时收集的数据显示，没有类似的种群增加，表明这是局部的而不是区域的增加。具体来说，根除计划无意中通过捕食减少了成体对幼体的控制，从而促进了种群爆发。中间实验证实，成体对幼体的捕食是与体型相关的，并且可以控制幼体的补充。基因组数据显示，该种群存在大量的隔离，种群内部动态是增加的原因，而不是来自其他地方的补充。更广泛地说，这个在水生系统中对特定阶段的过补偿进行的受控实验证明，对于具有有限连通性和类似生活史的物种的根除工作提供了一个重要的警示信息。
