Phylogeographic analyses strongly suggest cryptic speciation in the giant spiny frog (Dicroglossidae: Paa spinosa) and interspecies hybridization in Paa.

Shupei Ye,Guang Yang,Jiayong Zhang,Rongquan Zheng,Shixia Xu,Hua Huang,Brock Fenton

doi:10.1371/journal.pone.0070403

Shupei Ye, Guang Yang + Show 5 more

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https://doi.org/10.1371/journal.pone.0070403

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Journal: PloS one	Publication Date: Jul 31, 2013
Citations: 64	License type: CC BY 4.0

Affiliation: Zhejiang Normal University, Nanjing Normal University

Abstract

Species identification is one of the most basic yet crucial issues in biology with potentially far-reaching implications for fields such as conservation, population ecology, and epidemiology. The widely distributed but threatened frog Paa spinosa has been speculated to represent a complex of multiple species. In this study, 254 individuals representing species of the genus Paa were investigated along the entire range of P. spinosa: 196 specimens of P. spinosa, 8 specimens of P. jiulongensis, 5 specimens of P. boulengeri, 20 specimens of P. exilispinosa, and 25 specimens of P. shini. Approximately 1333 bp of mtDNA sequence data (genes 12S rRNA and 16S rRNA) were used. Phylogenetic analyses were conducted using maximum parsimony, maximum likelihood and Bayesian inference. BEAST was used to estimate divergence dates of major clades. Results suggest that P. spinosa can be divided into three distinct major lineages. Each major lineage totally corresponds to geographical regions, revealing the presence of three candidate cryptic species. Isolation and differentiation among lineages are further supported by the great genetic distances between the lineages. The bifurcating phylogenetic pattern also suggests an east–west dispersal trend during historic cryptic speciation. Dating analysis estimates that P. spinosa from Western China split from the remaining P. spinosa populations in the Miocene and that P. spinosa from Eastern China diverged from Central China in the Pliocene. We also found that P. exilispinosa from Mainland China and Hong Kong might have a complex of multiple species. After identifying cryptic lineages, we then determine the discrepancy between the mtDNA and the morphotypes in several individuals. This discrepancy may have been caused by introgressive hybridization between P. spinosa and P. shini.

Highlights

Biologists usually categorize species by morphology as the original tool [1], and morphological traits remain immensely important for taxonomic description and identification of species in the field
Sequences of the 12S rRNA fragment from previous studies [20,21,44] were shorter than those obtained in out study; one region with 51 bp of 12S rRNA was excluded for further analysis
Cryptic Species Complex Taxonomic decisions are usually based on recognizable morphological characteristics

Summary

Introduction

Biologists usually categorize species by morphology as the original tool [1], and morphological traits remain immensely important for taxonomic description and identification of species in the field. Identification and characterization of the world’s numerous cryptic species complexes have become an ongoing challenge for evolutionary biologists with potentially farreaching implications for fields such as biodiversity conservation [4], epidemiology [5,6], and biological control [7,8]. Molecular phylogenies and DNA sequence data are important for identification and discovery of cryptic biological diversity that usually cannot be distinguished by traditional non-genetic approaches [4,9]. A number of studies have revealed cryptic diversity among species of anurans by molecular genetic approaches in the last decade [10,11,12]

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