Meeting Abstract
P3.20 Sunday, Jan. 6 Lounging lizards and gut bugs: Testing the role of the social aggregations for transferring digestive microbes WEHRLE, BA*; ESPINOZA, RE; California State Univ., Northridge; California State Univ., Northridge bwehrle@uci.edu
Why sociality evolves is poorly understood, but both biotic and abiotic factors have been implicated. Sociality may have evolved in some herbivorous reptiles to aid the transfer of gut microbes. These endosymbionts are needed to digest plant fiber and the fermentation products contribute greatly to the 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 conspecifics’ feces. Early attempts to characterize this microbial community in iguanas provided crude measures of microbial turnover. Our study is the first to characterize the spatial, temporal, and social variation of these microbial communities using modern genomic techniques. We hypothesize that microbial communities will be more similar within sites, diversify over time, and will vary with social grouping. We observed and marked juvenile iguanas in social lounges at nine sites on and around Barro Colorado Island, Panamá over two reproductive seasons. Of the 540 focal observations, 38% were of social aggregations (mean = 2.9 lizards/group), yet very few were intergenerational interactions (0.7% of observations). Hatchlings in groups averaged 1.2 m from their nearest neighbor, although densities varied among sites. We collected hindgut microbe samples from iguanas over the first 60 days post-hatching. Microbe-specific DNA was isolated from samples and high-throughput sequenced 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 with lizard age.
