Data from: Exploring possible human influences on the evolution of Darwin's finches

Humans are an increasingly common influence on the evolution of natural populations. Potential arenas of influence include altered evolutionary trajectories within populations and modifications of the process of divergence among populations. We consider this second arena in the medium ground finch (Geospiza fortis) on Santa Cruz Island, Galápagos, Ecuador. Our study compared the G. fortis population at a relatively undisturbed site, El Garrapatero, to the population at a severely disturbed site, Academy Bay, which is immediately adjacent to the town of Puerto Ayora. The El Garrapatero population currently shows beak size bimodality that is tied to assortative mating and disruptive selection, whereas the Academy Bay population was historically bimodal but has lost this property in conjunction with a dramatic increase in local human population density. We here evaluate potential ecological-adaptive drivers of the differences in modality by quantifying relationships between morphology (beak and head dimensions), functional performance (bite force), and environmental characteristics (diet). Our main finding is that associations among these variables are generally weaker at Academy Bay than at El Garrapatero, possibly because novel foods are used at the former site irrespective of individual morphology and performance. These results are consistent with the hypothesis that the rugged adaptive landscapes promoting and maintaining diversification in nature can be smoothed by human activities, thus hindering ongoing adaptive radiation.

人类对自然种群演化的影响正日益普遍。这类影响的潜在场景包括种群内部演化轨迹的改变，以及种群间分化进程的调整。本研究以厄瓜多尔加拉帕戈斯群岛圣克鲁斯岛上的中地雀（Geospiza fortis）为研究对象，探讨第二类影响场景。
本研究将两处中地雀种群进行对比：一处是相对未受干扰的埃尔加拉帕特雷罗（El Garrapatero）种群，另一处是紧邻波多黎各阿约拉镇的严重受干扰区域学院湾（Academy Bay）种群。埃尔加拉帕特雷罗种群目前呈现喙尺寸双峰分布特征，该特征与选型交配及分裂选择相关；而学院湾种群历史上也曾存在双峰分布，但随着当地人口密度大幅增长，已丧失这一特性。
本研究通过量化形态特征（喙部与头部尺寸）、功能性能（咬合力）与环境特征（食物组成）之间的关联，评估了导致双峰分布模式差异的潜在生态适应驱动因素。核心发现为：学院湾种群中各变量间的关联普遍弱于埃尔加拉帕特雷罗种群，这可能是因为前者区域内的个体无论自身形态与性能如何，都会利用新型食物资源。
上述结果支持这一假说：推动并维持自然界物种分化的崎岖适应性景观，可因人类活动而趋于平缓，进而阻碍持续进行的适应辐射进程。