Department of Biology, University of Louisiana at Lafayette Lafayette, LA, USA.
Evol Appl. 2012 Sep;5(6):540-52. doi: 10.1111/j.1752-4571.2011.00233.x. Epub 2012 Jan 24.
Anthropogenic alterations in the natural environment can be a potent evolutionary force. For species that have specific habitat requirements, habitat loss can result in substantial genetic effects, potentially impeding future adaptability and evolution. The endangered black-capped vireo (Vireo atricapilla) suffered a substantial contraction of breeding habitat and population size during much of the 20th century. In a previous study, we reported significant differentiation between remnant populations, but failed to recover a strong genetic signal of bottlenecks. In this study, we used a combination of historical and contemporary sampling from Oklahoma and Texas to (i) determine whether population structure and genetic diversity have changed over time and (ii) evaluate alternate demographic hypotheses using approximate Bayesian computation (ABC). We found lower genetic diversity and increased differentiation in contemporary samples compared to historical samples, indicating nontrivial impacts of fragmentation. ABC analysis suggests a bottleneck having occurred in the early part of the 20th century, resulting in a magnitude decline in effective population size. Genetic monitoring with temporally spaced samples, such as used in this study, can be highly informative for assessing the genetic impacts of anthropogenic fragmentation on threatened or endangered species, as well as revealing the dynamics of small populations over time.
人为改变自然环境可能成为强大的进化力量。对于那些具有特定栖息地要求的物种来说，栖息地的丧失可能会导致重大的遗传影响，潜在地阻碍未来的适应性和进化。濒危的黑头莺（Vireo atricapilla）在 20 世纪的大部分时间里，繁殖栖息地和种群规模大幅收缩。在之前的一项研究中，我们报告了残余种群之间存在显著分化，但未能恢复瓶颈的强烈遗传信号。在这项研究中，我们使用俄克拉荷马州和德克萨斯州的历史和当代样本的组合，（i）确定种群结构和遗传多样性是否随时间发生变化，以及（ii）使用近似贝叶斯计算（ABC）评估替代的人口统计学假设。与历史样本相比，我们发现当代样本的遗传多样性较低，分化程度增加，表明碎片化产生了重大影响。ABC 分析表明，在 20 世纪早期发生了瓶颈，导致有效种群数量大幅下降。像本研究中使用的具有时间间隔样本的遗传监测，可以非常有效地评估人为破碎化对受威胁或濒危物种的遗传影响，并揭示小种群随时间的动态。
