Dimensions of amphibian alpha diversity in the New World

Abstract

Aim: The links between taxonomic, functional, and phylogenetic diversity and how these vary geographically are key to understanding how historical and contemporary processes have shaped communities at regional and local scales. Here, we evaluate the links between taxonomic, functional and phylogenetic diversity for the amphibians in the Continental Americas and how these vary geographically under an explicit hypothesis testing framework. Location: Continental Americas. Taxon: Amphibia. Methods: We identify spatial disparities between biodiversity dimensions (taxonomic, functional and phylogenetic) using geographically weighted regressions. Based on these mismatches we examined whether different eco-evolutionary processes would fit (competitive exclusion, habitat filtering, available ecological space, strong biotic interactions, speciation rates, and dispersion). Results: We found extensive variation in spatial mismatches between the three dimensions of biodiversity examined here. In general, at higher latitudes, we detected relatively little phylogenetic diversity, suggesting rapid functional diversification from temperate clades. In contrast, at low latitudes, environmental filtering mechanisms appear to be restricting functional diversity. Main conclusions: The geographical mismatches between dimensions of diversity suggest different eco-evolutionary causes. Patterns of diversification across amphibian lineages demonstrate how different environments can have contrasting effects on the different dimensions of diversity, potentially leading to decoupling. Neither dimension of alpha diversity of amphibians is a general predictor for another, and thus, general explanations for amphibian diversity and evolution should be avoided. Nonetheless, these dimensions can provide critical insights about conservation measures that explicitly emphasize evolutionary history, functionality or classic species richness.

Deconstructing the dimensions of alpha diversity in squamate reptiles (Reptilia: Squamata) across the Americas

“…The geographical patterns for taxonomic and phylogenetic diversity in squamate reptiles across the Americas are very similar to patterns seen in other taxa such as birds, mammals and amphibians (Blackburn & Gaston, 1996;Jenkins et al, 2013;Ochoa-Ochoa et al, 2020). They are also congruent with the global reptile patterns described by Roll et al (2017) and Gumbs et al (2020) in finding higher diversities in the tropics.…”

“…These are not the only ecological and evolutionary processes that may help explain observed geographical mismatches between different facets, but they are among the most studied (see Table 1 for a more comprehensive review of potential mechanisms and hypotheses). Also, these eco-evolutionary mechanisms can operate at different spatial and phylogenetic scales and under distinct environmental conditions, and they are not necessarily mutually exclusive hypotheses (Ochoa-Ochoa et al, 2020).…”

“…With the development of more sophisticated techniques for data analysis and integration with phylogenetic data, the gaps between ecology and evolution have narrowed, making the study of biodiversity increasingly complex (McGill et al, 2019). These advances have allowed the recognition of biodiversity as an integrative concept that may be decomposed into its fundamental components (also called facets or dimensions), including taxonomic, phylogenetic and functional diversity (Colwell, 2009; Devictor et al, 2010; Jarzyna & Jetz, 2016; Ochoa‐Ochoa et al, 2020). While these three are not the only existing facets, they have been heavily studied in recent decades since they can be relatively easily integrated, providing deeper insights about ecological and evolutionary processes.…”

Anticipating the potential impacts of Batrachochytrium salamandrivorans on Neotropical salamander diversity

“…While PD provides insights on the evolutionary history of the biotic assemblage (Faith, 2013), FD captures the diversity of relevant traits for ecosystem functioning (Petchey & Gaston, 2006). Efforts linking such dimensions have recently improved our understanding of the eco‐evolutionary processes underlying the conformation of the rich amphibian biota in the Neotropics (Ochoa‐Ochoa et al, 2020). A further required step is anticipating the potential impacts of contemporary threats (e.g., climate change, biological invasion, and emerging diseases) on such dimensions to develop effective and integrative conservation strategies.…”

The fungal pathogen Batrachochytrium salamandrivorans is not detected in wild and captive amphibians from Mexico

“…Considering the high amphibian richness present in Mexico, the high number of species in some category of risk, and the potential vulnerability in plethodontid species from laboratory infection trials, the introduction of Bsal into the country should be considered a major threat to amphibian biodiversity. Our survey includes regions that have a high amphibian taxonomic and functional diversity ( Ochoa-Ochoa et al, 2020 ; García-Rodríguez et al, 2022 ), and/or have a high or moderate Bsal habitat suitability: the Sierra Madre Oriental, the extreme eastern Trans-Mexican Volcanic Belt, southeastern Sierra Madre del Sur, mountains of Chiapas in Mexico ( García-Rodríguez et al, 2022 ). One example are the Mexican bolitoglossine salamanders Chiropterotriton spp.…”