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The gut microbiota is recognised as an essential asset for the normal functioning of animal biology. When wild animals are moved into captivity, the modified environmental pressures are expected to rewire the gut microbiota, yet whether this transition follows similar patterns across vertebrates is still unresolved due to the absence of systematic multi-species analyses. We performed a meta-analysis of gut microbiota profiles of 322 captive and 322 wild specimens from 24 vertebrate species. Our analyses yielded no overall pattern of diversity and compositional variation between wild and captive vertebrates, but a heterogeneous landscape of responses, which differed depending on the components of diversity considered. Captive populations showed enrichment patterns of human-associated microorganisms, and the minimal host phylogenetic signal suggests that changes between wild and captive populations are mainly driven by case-specific captivity conditions. Finally, we show that microbiota differences between wild and captive populations can impact evolutionary and ecological inferences that rely on hierarchical clustering-based comparative analyses of gut microbial communities across species., (© 2021. The Author(s).)

Several insectivorous bats have included fish in their diet, yet little is known about the processes underlying this trophic shift. We performed three field experiments with wild fishing bats to address how they manage to discern fish from insects and adapt their hunting technique to capture fish. We show that bats react only to targets protruding above the water and discern fish from insects based on prey disappearance patterns. Stationary fish trigger short and shallow dips and a terminal echolocation pattern with an important component of the narrowband and low frequency calls. When the fish disappears during the attack process, bats regulate their attack increasing the number of broadband and high frequency calls in the last phase of the echolocation as well as by lengthening and deepening their dips. These adjustments may allow bats to obtain more valuable sensorial information and to perform dips adjusted to the level of uncertainty on the location of the submerged prey. The observed ultrafast regulation may be essential for enabling fishing to become cost-effective in bats, and demonstrates the ability of bats to rapidly modify and synchronise their sensorial and motor features as a response to last minute stimulus variations.