Data from: Ecological drift and local exposures drive gastrointestinal bacterial community differences among Galápagos iguana populations

Diet strongly influences the intestinal microbial communities through species sorting. Alternatively, these communicates may differ because of chance variation in local microbial exposures or species losses among allopatric host populations (i.e. ecological drift). We investigated how these forces shape enteric communities of Galápagos marine and land iguanas. Geographically proximate populations shared more similar communities within a host ecotype, suggesting a role for ecological drift during host colonization of the islands. Additionally, evidence of taxa sharing between proximate heterospecific host populations suggests that contemporary local exposures also influence the gut community assembly. While selective forces such as host-bacterial interactions or dietary differences are dominant drivers of intestinal community differences among hosts, historical and contemporary processes of ecological drift may lead to differences in bacterial composition within a host species. Whether such differences in community structure translate into geographic variation in benefits derived from these intimate microbial communities remains to be explored.

饮食通过物种分选（species sorting）作用强烈影响肠道微生物群落。另一方面，这些群落的差异也可能源于异地宿主种群间本地微生物暴露的随机差异或物种丧失，即生态漂变（ecological drift）。本研究探究了这两类作用如何塑造加拉帕戈斯海鬣蜥与陆鬣蜥的肠道群落。同一宿主生态型中地理距离较近的种群拥有更为相似的群落，这表明生态漂变在宿主定居岛屿的过程中发挥了作用。此外，地理邻近的异种宿主种群间存在类群共享的现象，这说明当代本地微生物暴露同样会影响肠道群落的构建。尽管宿主-细菌互作、饮食差异等选择压力是驱动宿主间肠道群落差异的主要因素，但生态漂变的历史与当代过程仍可能导致同一宿主物种内细菌组成的差异。群落结构的此类差异是否会转化为这类亲密共生微生物群落所带来的益处的地理变异，仍有待进一步探究。