Meeting Abstract
In metazoans, complex microbial communities are found throughout epithelial tissues and influence host growth rate, life history, metabolism, ecology, and immunity. Furthermore, the host’s microbiome can mediate tolerance to environmental stress and facilitate adaptation. Despite the well-established functional importance of vertebrate microbiomes for host physiology and fitness, the putative role of symbionts mediating adaptation in vertebrate extremophiles remains unstudied. We are utilizing a system of a livebearing fish (Poecilia mexicana) that repeatedly colonized toxic sulfide springs in southern Mexico to explore how host-microbiome associations change upon colonization of extreme environments. This study system is excellent for understanding mechanisms of adaptation due to both strong sources of selection (hydrogen sulfide and hypoxia) driving adaptation and the naturally paired sulfidic and nonsulfidic populations that allow for comparative analyses. We collected skin, gill, and gut samples of P. mexicana across multiple sulfidic and nonsulfidic habitat pairs, as well as sediment and water samples, and used 16S rRNA amplicon sequencing to characterize the environmental and tissue microbiomes. This approach helps disentangle the evolutionary and environmental factors that shape host microbiomes, and it establishes a core extremophile microbiome consisting of taxa that are unique to—and consistently present in—fish from sulfide springs. Analyzing microbiomes within an evolutionary framework provides opportunities to understand how host-microbe associations arise and what role they play in adaptation.
