Macías-Duarte Alberto, Conway Courtney J, Culver Melanie
Arizona Cooperative Fish and Wildlife Research Unit School of Natural Resources and the Environment University of Arizona Tucson AZ USA.
Idaho Cooperative Fish & Wildlife Research Unit US Geological Survey University of Idaho Moscow ID USA.
Ecol Evol. 2020 Sep 17;10(19):10697-10708. doi: 10.1002/ece3.6725. eCollection 2020 Oct.
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 northern portion of the species' range (migration-driven breeding dispersal whereby long-distance migrants from Canada and the United States became year-round residents in the newly created irrigated agriculture areas in Mexico). We used 10 novel microsatellite markers to genotype 1,560 owls from 36 study locations in Canada, Mexico, and the United States. We found that burrowing owl populations are practically panmictic throughout the entire North American breeding range. However, an analysis of molecular variance provided some evidence that burrowing owl populations in northwestern Mexico and Canada together are more genetically differentiated from the rest of the populations in the breeding range, lending some support to our migration-driven breeding dispersal hypothesis. We found evidence of subtle genetic differentiation associated with irrigated agricultural areas in southern Sonora and Sinaloa in northwestern Mexico. Our results suggest that land use can produce location-specific population dynamics leading to subtle genetic structure even in the absence of dispersal barriers.
一个物种分布范围内的种群结构主要反映历史、生态和进化过程。然而，土地利用的大规模同步变化有可能导致栖息地质量改变，从而引起基因流动、种群结构和分布的变化。因此，一个物种分布范围内某一部分的土地利用变化可能解释其分布范围内其他部分的种群数量下降。例如，在20世纪下半叶，许多穴小鸮种群在该物种繁殖分布的北缘附近数量减少或灭绝。同一时期，墨西哥西北部大片多刺灌丛被改造成灌溉农业区。这些灌溉区现在可能是北美穴小鸮密度最高的地区。我们检验了这样一个假设：在墨西哥西北部新近形成的穴小鸮栖息地定居的穴小鸮，起源于该物种分布范围北部数量下降的迁徙种群（迁徙驱动的繁殖扩散，即来自加拿大和美国的长途迁徙者成为墨西哥新形成的灌溉农业区的全年居民）。我们使用10个新的微卫星标记，对来自加拿大、墨西哥和美国36个研究地点的1560只穴小鸮进行基因分型。我们发现，在整个北美繁殖范围内，穴小鸮种群实际上是随机交配的。然而，分子方差分析提供了一些证据，表明墨西哥西北部和加拿大的穴小鸮种群在基因上与繁殖范围内的其他种群差异更大，这为我们的迁徙驱动繁殖扩散假设提供了一些支持。我们发现了与墨西哥西北部索诺拉州南部和锡那罗亚州的灌溉农业区相关的细微遗传分化的证据。我们的结果表明，即使没有扩散障碍，土地利用也会产生特定地点的种群动态，导致细微的遗传结构。
