Phylogenetic relationships of toads of the Rhinella granulosa group (Anura: Bufonidae): a molecular perspective with comments on hybridization and introgression

Abstract

The Rhinella granulosa group consists of 13 species of toads distributed throughout open areas of South America and Panama. In this paper we perform a phylogenetic analysis considering all but one species of the group, employing five nuclear and four mitochondrial genes, for up to 7910 bp per specimen. Separate phylogenetic analyses under direct optimization (DO) of nuclear and mitochondrial sequences recovered the R. granulosa group as monophyletic and revealed topological incongruence that can be explained mainly by multiple events of hybridization and introgression, both mitochondrial and nuclear. The DO combined analysis, after the exclusion of putatively introgressed or heterozygous genomes, resulted in a phylogenetic hypothesis for the R. granulosa group in which most of the species are recovered as monophyletic, but with interspecific relationships poorly supported. The optimization of morphological (adult and larval), chromosomal, and behavioural characters resulted in 12 putative phenotypic synapomorphies for this species group and some other synapomorphies for internal clades. Our results indicate the need for additional population genetic studies on R. dorbignyi and R. fernandezae to corroborate the taxonomic status of both taxa. Finally, we discuss biological and genetic characteristics of Bufonidae, as possible explanations for the common occurrence of hybridization and introgression observed in some lineages of this family.

The complex evolutionary history of the tympanic middle ear in frogs and toads (Anura)

“…Additionally, based on the limited evidence presently available (see section S5 of the Supplementary Information ), the loss of TME structures in Bufonidae appears to be coincident with the origin of a scramble competition mating system in which males in dense aggregations attempt amplexus indiscriminately and struggle for possession of females 78 . In this mating system, acoustic territorial defence is absent and reliance on hearing for mate choice is greatly reduced or eliminated, as is the effectiveness of prezygotic isolating barriers like advertisement calls 78 , which presumably results in the natural interspecific hybridization observed in many bufonid species (see 79 and references therein).…”

Evaluating the diversity of Neotropical anurans using DNA barcodes

“…A 648-bp region of the mitochondrial Cytochrome Oxidase I (COI) gene is commonly used as a barcode for the identification of animal species, given that it is easily sequenced and provides excellent resolution for the identification of taxa, especially when combined with the analysis of other traits (Pereyra et al 2016). This is supported by the considerable divergence in sequences found by Hebert et al (2003) between 13,000 pairs of closely-related animal species, and reinforces the need for the analysis of more than a single, short sequence of DNA, which may produce inconclusive results (Blotto et al 2012, Pereyra et al 2016). …”

A new species ofPseudopaludicola(Anura, Leiuperinae) from Espírito Santo, Brazil

“…Conversely, P. mystacalis , throughout its broad distribution, reaches differences somewhat higher than 3%. It is clear that genetic divergence could vary among clades, as was previously shown for other anuran groups (i.e., Lötters et al, 2009 , Blotto et al, 2013 ; Pereyra et al, 2016 ), so observed genetic divergences should be taken with caution. In P. restinga sp.…”