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Open Access Research article

Evaluation of the taxonomic status of populations assigned to Phyllomedusa hypochondrialis (Anura, Hylidae, Phyllomedusinae) based on molecular, chromosomal, and morphological approach

Daniel Pacheco Bruschi1, Carmen Sílvia Busin2, Luís Felipe Toledo3, Gilda Andrade Vasconcellos4, Christine Strussmann5, Luiz Norberto Weber4, Albertina Pimentel Lima6, Jucivaldo Dias Lima7 and Shirlei Maria Recco-Pimentel1*

Author Affiliations

1 Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, Universidade de Campinas (UNICAMP), 13083-863 Campinas, SP, Brazil

2 Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade de Passo Fundo (UPF), CEP 99001-970 Passo Fundo, RS, Brazil

3 Museu de Zoologia "Prof. Adão José Cardoso", Instituto de Biologia, Universidade Estadual de Campinas, 13083-863 Campinas, SP, Brazil

4 Departamento de Biologia, Centro de Ciências da Saúde, Universidade Federal do Maranhão, 65085-580 São Luis, MA, Brazil

5 Departamento de Ciências Básicas e Produção Animal, Faculdade de Agronomia, Medicina Veterinária e Zootecnia, Universidade Federal de Mato Grosso, 78060-900 Cuiabá, MT, Brazil

6 Instituto Nacional de Pesquisas da Amazônia (INPA), 69060-001 Manaus, AM, Brazil

7 Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá, Divisão de Zoologia, 68912-250 Macapá, AP, Brazil

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BMC Genetics 2013, 14:70  doi:10.1186/1471-2156-14-70

Published: 12 August 2013

Abstract

Background

The taxonomic and phylogenetic relationships of the genus Phyllomedusa have been amply discussed. The marked morphological similarities among some species hamper the reliable identification of specimens and may often lead to their incorrect taxonomic classification on the sole basis of morphological traits. Phenotypic variation was observed among populations assigned to either P. azurea or P. hypochondrialis. In order to evaluate whether the variation observed in populations assigned to P. hypochondrialis is related to that in genotypes, a cytogenetic analysis was combined with phylogenetic inferences based on mitochondrial and nuclear sequences.

Results

The inter- and intra-population variation in the external morphology observed among the specimens analyzed in the present study do not reflect the phylogenetic relationships among populations. A monophyletic clade was recovered, grouping all the specimens identified as P. hypochondrialis and specimens assigned P. azurea from Minas Gerais state. This clade is characterized by conserved chromosomal morphology and a common C-banding pattern. Extensive variation in the nucleolar organizing region (NOR) was observed among populations, with four distinct NOR positions being recognized in the karyotypes. Intra-population polymorphism of the additional rDNA clusters observed in specimens from Barreiras, Bahia state, also highlights the marked genomic instability of the rDNA in the genome of this group. Based on the topology obtained in the phylogenetic analyses, the re-evaluation of the taxonomic status of the specimens from the southernmost population known in Brazil is recommended.

Conclusions

The results of this study support the need for a thorough revision of the phenotypic features used to discriminate P. azurea and P. hypochondrialis. The phylogenetic data presented here also contribute to an extension of the geographic range of P. hypochondrialis, which is known to occur in the Amazon basin and neighboring areas of the Cerrado savanna, where it may be sympatric with P. azurea, within contact zones. The misidentification of specimens may have led to inconsistencies in the original definition of the geographic range of P. azurea. The variability observed in the NOR of P. hypochondrialis reinforces the conclusion that these sites represent hotspots of rearrangement. Intraspecific variation in the location of these sites is the result of constant rearrangements that are not detected by classical cytogenetic methods or are traits of an ancestral, polymorphic karyotype, which would not be phylogenetically informative for this group.

Keywords:
Phyllomedusa; Morphological variation; Chromosome; Phylogenetic inference