Resource stability and geographic isolation are associated with genome divergence in western Palearctic crossbills

While many conifers produce annually variable seed crops, serotinous species (which hold seeds in cones for multiple years) represent unusually stable food resources for seed predators. Such stability is conducive to residency and potentially population divergence of consumers as exemplified by the Cassia crossbill (Loxia sinesciuris) in North America. We used genotyping-by-sequencing to test whether three Mediterranean subspecies of common crossbills (L. curvirostra) associated with the serotinous Aleppo pine (Pinus halepensis) were more genetically distinct than European crossbills associated with non-serotinous conifers. We assembled a Cassia crossbill draft genome as a reference for mapping GBS reads, and as a first step towards a more contiguous genome assembly. We found clear patterns of genetic divergence for each of the P. halepensis-associated subspecies. Geographic isolation, as promoted by resource stability and residency, is associated with genetic divergence of two of these...尽管多数针叶树每年的种子产量存在波动，但种子滞留型物种（serotinous species）——即种子可在球果中留存多年的类群——可为种子捕食者提供异常稳定的食物资源。这种稳定性有利于这类捕食者的定居行为，甚至可能推动其种群分化，以北美卡西亚交嘴雀（Loxia sinesciuris）为典型代表。我们采用测序分型（genotyping-by-sequencing, GBS）技术，旨在检验与种子滞留型阿勒颇松（Pinus halepensis）相关的3个地中海普通交嘴雀（Loxia curvirostra）亚种，是否比与非种子滞留型针叶树共生的欧洲交嘴雀具有更高的遗传分化程度。我们组装了卡西亚交嘴雀的草图基因组，用于GBS测序读段的比对分析，同时也为后续构建更高连续性的基因组组装序列奠定基础。研究结果显示，所有与阿勒颇松共生的亚种均呈现出显著的遗传分化模式。由食物资源稳定性与定居行为所推动的地理隔离，与其中两个亚种的遗传分化存在关联……