Meeting Abstract
Gut microbiomes are an ideal system for testing hypotheses about ecological community assembly, especially regarding the importance of diversity dependence in structuring communities. We compare gut microbiome richness across three communities that vary in host species richness to determine the effects of host community richness on microbiome richness. We sequence the hind-gut microbiomes from largely complete lizard and snake (squamate) communities across three latitudes (42 degrees north, 32 degrees north, and 12 degrees south) in the Western Hemisphere. The communities range from five host species, to 24, to 69, and the number of host higher taxa represented follows a similar increase towards the equator. Given the host gradient in species and phylogenetic diversity, gut microbiome lineage diversity might be expected to increase as well. However, we find no such increase either within or between hosts, at any level of microbial taxonomic structure. We explore the causes and consequences of this anti-gradient by examining the phylogenetic histories and ecological diversity of the hosts.
