Revealing cryptic diversity using molecular phylogenetics and phylogeography in frogs of the Scinax ruber and Rhinella margaritifera species groups

Abstract

Few studies to date have examined genetic variability of widespread tropical amphibian species over their distributional range using diVerent kinds of molecular markers. Here, we use genetic data in an attempt to delimit evolutionary entities within two groups of Neotropical frogs, the Scinax ruber species group and the Rhinella margaritifera species group. We combined mitochondrial and nuclear markers for a phylogenetic (a total of »2500 bp) and phylogeographic study (»1300 bp) to test the reliability of the currently accepted taxonomic assignments and to explore the geographic structure of their genetic variation, mainly based upon samples from the French Guianan region. Phylogenetic analyses demonstrated the polyphyly of Scinax ruber and Rhinella margaritifera. S. ruber consists of six lineages that may all merit species status. ConXicting signals of mitochondrial and nuclear markers indicated, among some Scinax lineages and species, the possibility of ongoing hybridization processes. R. margaritifera consisted of 11 lineages which might represent distinct species as well. Phylogeographic analyses added further information in support of the speciWc status of these lineages. Lineages of low divergence were found in sympatry and were reciprocally monophyletic for mitochondrial as well as nuclear genes, indicating the existence of young lineages that should be awarded species status. Our results highlight the utility of combining phylogenetic and phylogeographic methods, as well as the use of both mitochondrial and nuclear markers within one study. This approach helped to better understand the evolutionary history of taxonomically complex groups of species. The assessment of the geographic distribution of genetic diversity in tropical amphibian communities can lead to conclusions that diVer strongly from prior analyses based on the occurrence of currently recognized species alone. Such studies, therefore, hold the potential to contribute to a more objective assessment of amphibian conservation priorities in tropical areas.

Anurans of the Urucu Petrol Basin, municipality of Coari, State of Amazonas, northern Brazil

“…Among the taxa that have taxonomic problems are the following genera and species groups: Allobates, Dendropsophus, Adenomera, Pristimantis and Rhinella gr. margaritifera (Angulo et al 2003;Fouquet et al 2007 Rhinella gr. margaritifera, Adenomera gr.…”

Study of closely related species within the Physalaemus cuvieri group (Anura): contribution of microsatellite markers

“…One crucial point in delimiting cryptic species is to distinguish between broad admixture and narrow contact zone or even restricted hybridization (Fouquet et al, 2007). There are several but perhaps incorrect assumptions about cryptic species, indicating that their speciation was so recent that morphological or other diagnosable traits have not yet evolved.…”

Phylogeographic analysis reveals two cryptic species of the endangered fern Ceratopteris thalictroides (L.) Brongn. (Parkeriaceae) in China

“…Both molecular systematics and phylogeographic studies often reveal evidence of cryptic variation, and in many cases lead to the discovery of new species (Masuyama et al 2002;Avise 2004;Fouquet et al 2007;Seidel et al 2009;Unmack and Dowling 2010). A phylogeographic approach can reveal the nature of evolutionary diversification and biogeographical segregation (Wilke and Pfenninger 2002;Avise 2004).…”