Exploring the Development of Wild Microbiomes in the Eastern Fence Lizard.

This study examines the gut microbiome from faecal samples of a reptilian model (Sceloporus undulatus). The dynamic host-symbiote interactions between gut microbiota are essential in metabolic processes and overall health of the host organism. We used 16S rRNA gene sequencing to profile the bacterial community from the guts of wild Eastern Fence Lizards. Microbiome profiles were collected at four distinct time points when lizards were actively foraging in the environment and across four age groups, aiming to characterise the natural variation in bacterial diversity. Environmental bacteria such as Mycobacterium and Pantoea in young of year (YOY) lizards underwent successional microbiome changes to taxa including Caproiciproducens, Eubacterium, Fusobacterium and Roseburia in adults, reflecting dietary shifts from maternal nutrients and early-stage prey to fibre-rich arthropod diets. Juvenile lizards exhibited a simple gut microbiome dominated by pioneer colonisers (Firmicutes, Bacteroidota and Proteobacteria), with alpha diversity increasing rapidly within a month to near adult levels. This research extends our understanding of reptilian microbiomes, capturing a snapshot of the ecological complexities of Eastern Fence Lizard microbiomes. As wild lizards mature, their gut microbiome becomes more stable and resilient to environmental disturbances, developing a diverse and balanced bacterial community that supports functional redundancy and ecosystem stability.