Dimensions of amphibian alpha diversity in the New World

Local biological diversity, also known as alpha diversity, has three different components: the number of species in a given area (taxonomic diversity), the number of distinct traits that these species have (functional diversity) and their evolutionary distinctiveness (phylogenetic diversity). The relationships among these components of diversity vary across geography reflecting the differences in eco-evolutionary processes among distant regions.

(Above) 3D visualization of the empirical relationships between functional diversity, phylogenetic diversity and taxonomic diversity for amphibians in the Continental Americas based on our theoretical framework.

This study was motivated by the fact that different components of biological diversity have been shown to vary slightly in their geographical distribution: while species richness, phylogenetic diversity and functional diversity are broadly correlated, there are some regions where one measure of diversity is higher or lower than expected based on the others.

FROM THE COVER: Ochoa-Ochoa, LM, Mejía-Domínguez, NR, Velasco, JA, Dimitrov, D, Marske, KA. Dimensions of amphibian alpha diversity in the New World. J Biogeogr. 2020; 47: 2293– 2302. https://doi.org/10.1111/jbi.13948

We discussed extensively the possibilities to integrate these three dimensions of biological diversity in a single framework and developed a set of hypotheses about the potential drivers of variability in the relationships among the diversities.  We then mapped the spatial distribution of these diversity measurements and use our theoretical framework to explore the processes that may have generated the spatial patterns of amphibian diversity in the New World as we know it today.

Quilticohyla zoque is a treefrog species from the family Hylidae
from Nahá reserve, Chiapas, Mexico. Photo: LMMO.

We found that although the three aspects of diversity showed similar patterns, the geographical variation in the relationship between diversities suggested that a variety of processes, including ecological opportunity, habitat filtering, competitive interactions, among others have had different impacts on the different components of diversity. We also found regional differences dominant processes shaping diversity patterns.

Finally, we concluded that neither dimension of amphibian alpha diversity is a general predictor for other dimensions. Thus a single explanation about ecological and evolutionary processes underlying geographical variation in amphibian diversity is not possible. Our findings have major implications for conservation because setting conservation priorities may require analyses to determine which is the most important dimension of diversity to be conserved. Thus, the question of whether to give priority to history (e.g., antique lineages, evolutionary uniqueness), to high functional diversity (with rare or unique functions) or to taxonomic diversity (number of species) is critical.

Rhinophrynus dorsalis, is a Mexican burrowing toad from the family Rhinophrynidae
from Nahá reserve, Chiapas, Mexico. Photo: LMMO.

Ideally, if we want to preserve a wider range of the evolutionary spectrum, the aim should be, not only to conserve as many species as possible, but also to conserve a broad selection of different phylogenetic lineages and life history traits (functions). We expect that our findings will stimulate a new generation of local studies aimed at deciphering how diversity in ecological roles, evolutionary heritage and species numbers was assembled by ecological and evolutionary processes at finer spatial scales.

Written by:
Leticia Margarita Ochoa-Ochoa, Full Professor, Evolutionary Biology Department, Museum of Zoology, Faculty of Sciences, UNAM.
Nancy R. Mejía-Domínguez, Associated Researcher, Unidad de Bioinformática, Bioestadística y Biología Computacional, Red de Apoyo a la Investigación (RAI). Coordinación de la Investigación Científica, UNAM.
Julian A. Velasco, Associated Researcher, Centro de Ciencias de la Atmósfera, UNAM.
Dimitar Dimitrov, Associate Professor, Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway.
Katharine A. Marske, Assistant Professor, Geographical Ecology Group, Department of Biology, University of Oklahoma, Norman, Oklahoma, USA

For more information:
@Lety_OchoaOchoa /  http://academicos.fciencias.unam.mx/leticiaochoa/
@MejiaDNancy / https://sites.google.com/view/biostatisticsrai-unam/
@juvelas / https://www.atmosfera.unam.mx/ciencias-atmosfericas/cambio-climatico-y-radiacion-solar/julian-a-velasco-vinasco/
@spidersphylo / http://www.dimitardimitrov.name
@kamarske / Kamarske.org

Published by jbiogeography

Contributing to the growth and societal relevance of the discipline of biogeography through dissemination of biogeographical research.

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