Agriculture creates subtle genetic structure among migratory and non-migratory populations of burrowing owls throughout North America

Population structure across a species distribution primarily reflects historical, ecological and evolutionary processes. However, large-scale contemporaneous changes in land use have the potential to create changes in habitat quality and thereby cause changes in gene flow, population structure, and distributions. As such, land-use changes in one portion of a species range may explain declines in other portions of their range. For example, many burrowing owl populations have declined or become extirpated near the northern edge of the species’ breeding distribution during the second half of the 20th century. In the same period, large extensions of thornscrub were converted to irrigated agriculture in northwestern Mexico. These irrigated areas may now support the highest densities of burrowing owls in North America. We tested the hypothesis that burrowing owls that colonized this recently created owl habitat in northwestern Mexico originated from declining migratory populations from the no...物种分布区的种群结构主要反映历史、生态与演化过程。然而，大规模同期土地利用变化可能改变栖息地质量，进而引发基因流、种群结构与分布范围的改变。据此，物种分布区内某一区域的土地利用变化，或可解释其分布范围内其他区域的种群衰减现象。例如，20世纪下半叶，该物种繁殖分布区北缘附近的许多穴小鸮（burrowing owl）种群出现衰减甚至局部灭绝。同期，墨西哥西北部大片刺灌丛（thornscrub）被改造为灌溉农业用地。如今，这些灌溉区域可能拥有北美密度最高的穴小鸮种群。本研究验证了如下假说：在墨西哥西北部新近形成的穴小鸮栖息地中拓殖的个体，其来源为某个正在衰减的迁徙种群——