Meeting Abstract

23.2  Wednesday, Jan. 4  Why do lizards lounge? The role of social aggregations in exchanging microbial communities among hatchling Green Iguanas WEHRLE, B.A.*; ESPINOZA, R.E.; CSU Northridge; CSU Northridge

Why sociality evolves is poorly understood, but both biotic and abiotic factors have been implicated. Sociality may have evolved in some herbivorous reptiles to foster the transfer of gut microbes. These endosymbionts are needed to digest plant fiber and their fermentation products can contribute substantially to their host’s energy budget, but this symbiosis is poorly understood. Green iguanas (Iguana iguana) are herbivorous throughout life, yet hatch with sterile guts. So how do they acquire their gut microbes? Although rare in lizards, social interactions are a hypothesized route of microbe transfer via direct contact and/or eating feces of conspecifics. Early attempts (>30 years ago) to characterize this microbial community in hatchling iguanas provided crude measures of microbial turnover. Our study is the first to characterize the spatial, temporal, and social variation of these vital microbial communities using modern genomic techniques. We hypothesize that there will be microbial community variation more consistent with social transfer than individual variation. We observed and individually marked juvenile iguanas in social lounges at eight sites on and around Barro Colorado Island, Panama over two reproductive seasons. Of the 540 focal observations of hatchlings, 38% were of social aggregations (mean = 2.9 lizards/ group). Hatchlings in groups averaged 1.2 m from their nearest neighbor (range = 0–6 m), although densities varied among sites. We collected microbe samples from iguanas and their environments over the first 60 days post-hatching. Microbe-specific DNA will be isolated from samples and pyrosequenced to characterize the gut microbe communities of iguanas over space, time, and with respect to observed social interactions. We predict that microbial communities will be most similar among proximate hatchlings and will increase in diversity over time.