Divergence, gene flow, and the origin of leapfrog geographic distributions: The history of colour pattern variation in Phyllobates poison‐dart frogs

Abstract

The geographic distribution of phenotypic variation among closely related populations is a valuable source of information about the evolutionary processes that generate and maintain biodiversity. Leapfrog distributions, in which phenotypically similar populations are disjunctly distributed and separated by one or more phenotypically distinct populations, represent geographic replicates for the existence of a phenotype, and are therefore especially informative. These geographic patterns have mostly been studied from phylogenetic perspectives to understand how common ancestry and divergent evolution drive their formation. Other processes, such as gene flow between populations, have not received as much attention. Here, we investigate the roles of divergence and gene flow between populations in the origin and maintenance of a leapfrog distribution in Phyllobates poison frogs. We found evidence for high levels of gene flow between neighbouring populations but not over long distances, indicating that gene flow between populations exhibiting the central phenotype may have a homogenizing effect that maintains their similarity, and that introgression between 'leapfroging' taxa has not played a prominent role as a driver of phenotypic diversity in Phyllobates. Although phylogenetic analyses suggest that the leapfrog distribution was formed through independent evolution of the peripheral (i.e. leapfrogging) populations, the elevated levels of gene flow between geographically close populations poise alternative scenarios, such as the history of phenotypic change becoming decoupled from genome-averaged patterns of divergence, which we cannot rule out. These results highlight the importance of incorporating gene flow between populations into the study of geographic variation in phenotypes, both as a driver of phenotypic diversity and as a confounding factor of phylogeographic inferences.

Molecular physiology of pumiliotoxin sequestration in a poison frog

“…Using the largest ORF protein sequence of this gene we used tblastn against BLAST nucleotide databases made from previously assembled unpublished transcriptomes or genomes in five other poison frog species: Oophaga sylvatica (transcriptome), Ranitomeya imitator (transcriptome), Epipedobates tricolor (transcriptome), Allobates femoralis (genome), and Mantella aurantiaca (transcriptome, Family Mantellidae, an independent origin of chemical defense sequestration in amphibians [25]). The D. auratus and P. bicolor sequences were found using the same method from previously published transcriptomes [39,40]. The D. tinctorius TRINI-TY_DN15846_c0_g2 protein sequence and largest ORF of the top BLAST hit from each of these transcriptomes was translated and aligned to the human CYP2D6 protein sequence to identify amino acid differences in important binding residues [41].…”

Divergence With Gene Flow and Contrasting Population Size Blur the Species Boundary in Cycas Sect. Asiorientales, as Inferred From Morphology and RAD-Seq Data

“…There are two main hypotheses for the leapfrog pattern ( Remsen, 1984 ; Cadena et al, 2011 ; Marquez et al, 2020 ). The first hypothesis is the shared common ancestor of disjunct populations, which could be attributed to the long-distance Kuroshio hitchhike of bulbils.…”

Genetic basis of aposematic coloration in a mimetic radiation of poison frogs

“…Coloration is one of the most eco-evolutionarily important traits of dendrobatid frogs, yet little is known regarding its genetic basis (29), except for a few transcriptomic studies that generated extensive lists of candidate genes (12,30). We used divergence and association mapping to identify candidate genes, which we subsequently validated using linkage analyses in pedigrees.…”