New evidence for parallel evolution of colour patterns in Malagasy poison frogs (<i>Mantella</i>)

<jats:title>Abstract</jats:title><jats:p>Malagasy poison frogs of the genus <jats:italic>Mantella</jats:italic> are diurnal and toxic amphibians of highly variable and largely aposematic coloration. Previous studies provided evidence for several instances of homoplastic colour evolution in this genus but were unable to sufficiently resolve relationships among major species groups or to clarify the phylogenetic position of several crucial taxa. Here, we provide cytochrome <jats:italic>b</jats:italic> data for 143 individuals of three species in the <jats:italic>Mantella madagascariensis</jats:italic> group, including four newly discovered populations. Three of these new populations are characterized by highly variable coloration and patterns but showed no conspicuous increase of haplotype diversity which would be expected under a scenario of secondary hybridization or admixture of chromatically uniform populations. Several populations of these variable forms and of <jats:italic>M. crocea</jats:italic> were geographically interspersed between the distribution areas of <jats:italic>Mantella aurantiaca</jats:italic> and <jats:italic>Mantella milotympanum</jats:italic>. This provides further support for the hypothesis that the largely similar uniformly orange colour of the last two species evolved in parallel. Phylogenies based on over 2000 bp of two nuclear genes (<jats:italic>Rag‐1</jats:italic> and <jats:italic>Rag‐2</jats:italic>) identified reliably a clade of the <jats:italic>Mantella betsileo</jats:italic> and <jats:italic>Mantella laevigata</jats:italic> groups as sister lineage to the <jats:italic>M. madagascariensis</jats:italic> group, but did not support species within the latter group as monophyletic. The evolutionary history of these frogs might have been characterized by fast and recurrent evolution of colour patterns, possibly triggered by strong selection pressures and mimicry effects, being too complex to be represented by simple bifurcating models of phylogenetic reconstruction.</jats:p>