Comparative assessment of Texas horned lizard (Phrynosoma cornutum) gut microbiome diversity and composition throughout transition from captivity to wild

Abstract

Microbiomes play a key role in the health of animal hosts. To improveconservation translocation programs like headstarting, it is necessary toconsider how the structure of these programs impact the host-associatedmicrobiome. Bringing animals into captivity introduces novel diets andenvironments; however, the extent to which these factors contribute to thestructure of the host’s gut microbiome remains poorly understood. Additionally,it is unclear if periods of captivity leave a lasting signature on the host-associatedgut microbiome, which could impact individual health and fitness in the longterm.In this study, we repeatedly sampled the gut microbiome of a cohort ofheadstart Texas horned lizards (Phrynosoma cornutum) throughout theirtransition from captivity to the wild. We also collected samples of extrinsicmicrobial communities present in their captive and wild diet and environment.Finally, we sampled the gut microbiome of wild resident lizards to serve as abaseline comparison. Using 16S rRNA microbial inventories, we examineddifferences in microbial community composition and diversity between prereleaseheadstart, post-release headstart, and resident lizards of the wildpopulation. Additionally, we assessed the contribution of environmental anddietary microbial communities to the assembly of P. cornutum gut microbiomesin captivity and the wild. Our results suggest captive P. cornutum harbor gutmicrobiomes that are distinct from their wild counterparts. However, within twomonthspost-release, the headstart gut microbiome restructures to beindistinguishable from the wild resident microbiome. Microbiomes associated with the captive diet and environment are distinct in beta diversity, but not alphadiversity, from those in the wild. Our results provide important insights into hostassociatedmicrobiome dynamics associated with transition from captivity to thewild and can be used to inform conservation translocation practices.