Moyle, Robert GManthey, Joseph D.2017-05-072017-05-072015-12-312015http://dissertations.umi.com/ku:14414https://hdl.handle.net/1808/23942Sky islands are disjunct patches of montane forested habitat in a matrix of desert, grasslands, and scrub. I investigated intraspecific evolutionary biology of two bird species—the White­‐breasted Nuthatch (Sitta carolinensis) and the Brown Creeper (Certhia americana)—in the Madrean Archipelago sky islands (Arizona, USA), a biodiversity and evolution hotspot. In addition, I explored patterns of codiversification of these two birds and their associated gut microbial communities. The two bird studies revealed different patterns of diversification within the sky islands. The White­‐breasted Nuthatch exhibits a pattern of isolation by environment, where genetic differences among populations are related to environmental differences of those localities. In contrast, the Brown Creeper has a strong genetic break between northern and southern populations, with no evidence of gene flow between lineages. When I investigated codiversification of birds and their microbial communities, I found no relationship between host genetic diversity and microbial community alpha diversity, while genetic differentiation between birds was significantly related with beta diversity between microbial communities. This dissertation provides a first step in comparative evolutionary biology of Madrean Archipelago avian taxa, and adds to the knowledge of the factors shaping microbial community diversity in wild animals.100 pagesenCopyright held by the author.ZoologyBioinformaticsEvolution & developmentbirdsgenomicshybrid zoneisolation by environmentmicrobiotasky islandsDissertationhttps://orcid.org/0000-0003-2765-7611openAccess