Conclusion
Many studies have focused on understanding digestion and assimilation
within a variety of vertebrates and invertebrates, but there is limited
information about the cooperative process between the host intestine
cells and gut microbiota, and their role in eco-evolutionary dynamics
during rapid species diversification (German et al. 2015; Terra et al.
2019; Baldo et al. 2017). We found evidence for a genetically-based
adaptive shift in the scale-eater microbiome, even when hosts were
reared in identical environments on identical non-scale diets. However,
it is still unknown to what extent this microbiome shift will improve
digestion of the collagen found in scales, for example, as demonstrated
for the gut fauna in the scale-eating khavalchor catfish (Gosavi et al.
2018). Despite unique and highly specialized pupfish dietary adaptations
within shared hypersaline lake habitats, overall gut microbial diversity
did not follow the expected pattern of rapid diversification and
divergence as observed in their hosts, calling into question how
eco-evolutionary dynamics between host and symbiont proceed during
adaptive radiation.