Convergence of gut microbiota in myrmecophagous amphibians.

The gut microbiome composition of terrestrial vertebrates is known to converge in response to common specialized dietary strategies, like leaf-eating (folivory) or ant- and termite-eating (myrmecophagy). To date, such convergence has been studied in mammals and birds, but has been neglected in amphibians. Here, we analysed 15 anuran species (frogs and toads) representing five Neotropical families and demonstrated the compositional convergence of the gut microbiomes of distantly related myrmecophagous species. Specifically, we found that the gut microbial communities of bufonids and microhylids, which have independently evolved myrmecophagy, were significantly more similar than expected based on their hosts' evolutionary divergence. Conversely, we found that gut microbiome composition was significantly associated with host evolutionary history in some cases. For instance, the microbiome composition of Xenohyla truncata, one of the few known amphibians that eat fruits, was not different from those of closely related tree frogs with an arthropod generalist diet. Bacterial taxa overrepresented in myrmecophagous species relative to other host families include Paludibacter, Treponema, and Rikenellaceae, suggesting diet-mediated selection and prey-to-predator transmission likely driving the observed compositional convergence. This study provides a basis for examining the roles of the gut microbiome in host tolerance and sequestration of toxic alkaloids from ants and termites.

Cetartiodactyla: Updating a time-calibrated molecular phylogeny.

Cetartiodactyla comprises one of the most diverse mammal radiations. Currently, 23 families, 131 genera and more than 330 species are recognized. Several studies have been trying to resolve its phylogenetic relationships. The most comprehensive dated phylogenetic hypothesis available includes only 55% of the extant species, precluding a clear understanding of ecological and evolutionary patterns in Cetartiodactyla. Here, we gathered all mitochondrial genetic data available in GenBank to build a robust Cetartiodactyla calibrated phylogenetic tree using 21 fossil calibration points. We found mitogenomic data for 225 species and included other 93 species from which there was at least one mitochondrial gene available. Using a Bayesian approach, we generated a dated tree comprising 90% of the extant Cetartiodactyla species (n = 318). The major lineages showed robust support and families divergence times are congruent with the available fossil evidence and with previously published phylogenetic hypotheses. By making available a dated phylogeny with extensively sampled clades, we expect to foster future studies on the origin, tempo and mode of Cetartiodactyla diversification.

The combined role of dispersal and niche evolution in the diversification of Neotropical lizards.

Ecological requirements and environmental conditions can influence diversification across temporal and spatial scales. Understanding the role of ecological niche evolution under phylogenetic contexts provides insights on speciation mechanisms and possible responses to future climatic change. Large-scale phyloclimatic studies on the megadiverse Neotropics, where biomes with contrasting vegetation types occur in narrow contact, are rare. We integrate ecological and biogeographic data with phylogenetic comparative methods, to investigate the relative roles of biogeographic events and niche divergence and conservatism on the diversification of the lizard genus Kentropyx Spix, 1825 (Squamata: Teiidae), distributed in South American rainforests and savannas. Using five molecular markers, we estimated a dated species tree, which recovered three clades coincident with previously proposed species groups diverging during the mid-Miocene. Biogeography reconstruction indicates a role of successive dispersal events from an ancestral range in the Brazilian Shield and western Amazonia. Ancestral reconstruction of climatic tolerances and niche overlap metrics indicates a trend of conservatism during the diversification of groups from the Amazon Basin and Guiana Shield, and a strong signal of niche divergence in the Brazilian Shield savannas. Our results suggest that climatic-driven divergence at dynamic forest-savanna borders might have resulted in adaptation to new environmental niches, promoting habitat shifts and shaping speciation patterns of Neotropical lizards. Dispersal and ecological divergence could have a more important role in Neotropical diversification than previously thought.