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| Distribution of sequenced individuals of Epipedobates, their type localities (stars), and estimated divergence times. in López-Hervas, Santos, Ron, Betancourth-Cundar, Cannatella et Tarvin, 2024. |
Highlights:
• The poison frog genus Epipedobates is ∼11 My old and contains eight putative species.
• Inconspicuous Epipedobates spp. are more deeply diverged genetically than aposematic spp.
• We reorganize the E. boulengeri/espinosai species complex into four species.
• We synonymize E. darwinwallacei with E. espinosai.
• We provide the first genetic data for E. narinensis.
Abstract
Poison frogs (Dendrobatidae) are famous for their aposematic species, having a combination of diverse color patterns and defensive skin toxins, yet most species in this family are inconspicuously colored and considered non-aposematic. Epipedobates is among the youngest genus-level clades of Dendrobatidae that includes both aposematic and inconspicuous species. Using Sanger-sequenced mitochondrial and nuclear markers, we demonstrate deep genetic divergences among inconspicuous species of Epipedobates but relatively shallow genetic divergences among conspicuous species. Our phylogenetic analysis includes broad geographic sampling of the inconspicuous lineages typically identified as E. boulengeri and E. espinosai, which reveals two putative new species, one in west-central Colombia (E. sp. 1) and the other in north-central Ecuador (E. aff. espinosai). We conclude that E. darwinwallacei is a junior subjective synonym of E. espinosai. We also clarify the geographic distributions of inconspicuous Epipedobates species including the widespread E. boulengeri. We provide a qualitative assessment of the phenotypic diversity in each nominal species, with a focus on the color and pattern of inconspicuous species. We conclude that Epipedobates contains eight known valid species, six of which are inconspicuous. A relaxed molecular clock analysis suggests that the most recent common ancestor of Epipedobates is ∼ 11.1 million years old, which nearly doubles previous estimates. Last, genetic information points to a center of species diversity in the Chocó at the southwestern border of Colombia with Ecuador. A Spanish translation this text is available in the supplementary materials.
Keywords: Aposematism, Cryptic species, Genetic divergence, Polytypic species, Species delimitation, Phylogenetics
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| phylogeny of Epipedobates |
Conclusion:
Epipedobates forms a radiation of species on the west of the Andes in northern Peru, Ecuador, and Colombia. Epipedobates is a model clade for studying the relationship between phenotypic and genetic divergence. The boundaries between species pairs are difficult to assess. We found that the nominal species Epipedobates “boulengeri” included cryptic and understudied diversity; i.e., individuals included in that species now correspond to E. espinosai, E. aff. espinosai, and E. sp. 1. In contrast, a relatively young clade contains three phenotypically distinctive species, E. anthonyi, E. machalilla and E. tricolor, with very low genetic divergence despite high levels of morphological divergence. Two of these species might have evolved conspicuous coloration independently, yet introgression and relatively recent divergence in less than 2 Mya might also explain such events. We found evidence of gene flow between E. machalilla and E. aff. espinosai, and we suggest that further sampling using highly variable markers from genome-wide data is needed to assess introgression between these and possibly other pairs of Epipedobates species.
Karem López-Hervas, Juan C. Santos, Santiago R. Ron, Mileidy Betancourth-Cundar, David C. Cannatella and Rebecca D. Tarvin. 2024. Deep Divergences among inconspicuously colored Clades of Epipedobates Poison Frogs. Molecular Phylogenetics and Evolution. In Press, 108065. DOI: 10.1016/j.ympev.2024.108065
Resumen: Las ranas venenosas (Dendrobatidae) son famosas por sus especies aposemáticas, que se caracterizan por una combinación de diversos patrones de color y toxinas cutáneas defensivas. Sin embargo, la mayoría de las especies de esta familia tienen colores inconspicuos y no se consideran aposemáticas. Epipedobates se encuentra entre los clados más jóvenes a nivel de género de Dendrobatidae que incluye especies tanto aposemáticas como inconspicuos. Usando marcadores mitocondriales y nucleares, demostramos profundas divergencias genéticas entre especies inconspicuos de Epipedobates pero divergencias genéticas relativamente superficiales entre especies conspicuas. Nuestro análisis filogenético incluye un amplio muestreo geográfico de los linajes inconspicuos típicamente identificados como E. boulengeri y E. espinosai. Los resultados revelan dos nuevas especies putativas, una en el centro-oeste de Colombia (E. sp. 1) y la otra en el centro-norte de Ecuador (E. aff. espinosai). Determinamos que E. darwinwallacei es un sinónimo subjetivo menor de E. espinosai y aclaramos las distribuciones geográficas de las especies inconspicuos de Epipedobates, incluyendo E. boulengeri. Con una evaluación cualitativa enfocado en el color y el patrón de las especies inconspicuas describimos la diversidad fenotípica en cada especie nominal. Concluimos que el género Epipedobates contiene ocho especies válidas conocidas, seis de las cuales son en su mayoría inconspicuas. Un análisis de reloj molecular relajado nos sugiere que el ancestro común más reciente de Epipedobates tiene ∼ 11,1 millones de años, lo que casi duplica las estimaciones anteriores. Por último, la información genética apunta a un centro de diversidad de especies en el Chocó en la frontera suroeste de Colombia con Ecuador. Una traducción al español de este texto está disponible en los materiales suplementarios.
