Data from: Environmental selection is a main driver of divergence in house sparrows (Passer domesticus) in Romania and Bulgaria

Both neutral and adaptive evolutionary processes can cause population divergence, but their relative contributions remain unclear. We investigated the roles of these processes in population divergence in house sparrows (Passer domesticus) from Romania and Bulgaria, regions characterized by high landscape heterogeneity compared to Western Europe. We asked whether morphological divergence, complemented with genetic data in this human commensal species, was best explained by environmental variation, geographic distance, or landscape resistance—the effort it takes for an individual to disperse from one location to the other—caused by either natural or anthropogenic barriers. Using generalized dissimilarity modeling, a matrix regression technique that fits biotic beta diversity to both environmental predictors and geographic distance, we found that a small set of climate and vegetation variables explained up to ~30% of the observed divergence, whereas geographic and resistance distances played much lesser roles. Our results are consistent with signals of selection on morphological traits and of isolation by adaptation in genetic markers, suggesting that selection by natural environmental conditions shapes population divergence in house sparrows. Our study thus contributes to a growing body of evidence that adaptive evolution may be a major driver of diversification.

中性进化过程与适应性进化过程均可引发种群分化，但二者的相对贡献迄今仍未明确。我们以罗马尼亚与保加利亚的家麻雀（Passer domesticus）为研究对象——相较于西欧，该区域的景观异质性更为突出——探究了这两类过程在种群分化中所扮演的角色。针对这一与人共生的物种，我们结合形态分化数据与遗传信息，旨在明确下述三类因素中哪一项可最优解释其种群分化：环境变异、地理距离，或是由自然或人为障碍所导致的景观阻力——即个体从一处扩散至另一处所需付出的代价。本研究采用广义相异性建模（generalized dissimilarity modeling）——一种将生物β多样性与环境预测因子、地理距离进行拟合的矩阵回归技术——开展分析，结果显示，少量气候与植被变量即可解释约30%的观测种群分化，而地理距离与阻力距离的解释权重则相对较低。我们的研究结果与形态性状的适应性选择信号以及遗传标记中的适应性隔离信号相契合，表明自然环境条件介导的选择作用塑造了家麻雀的种群分化格局。综上，本研究为“适应性进化或为物种多样化的核心驱动因素”这一不断积累的证据链提供了新的支撑。