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Testing assertions of widespread introgressive hybridization in a clade of neotropical toads with low mate selectivity (Rhinella granulosa species group)

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Autor(es):
Rivera, Danielle ; Prates, Ivan ; Caldwell, Janalee P. ; Rodrigues, Miguel Trefaut ; Fujita, Matthew K.
Número total de Autores: 5
Tipo de documento: Artigo Científico
Fonte: HEREDITY; v. 130, n. 1, p. 8-pg., 2022-11-05.
Resumo

Discordance between different genomic regions, often identified through multilocus sequencing of selected markers, presents particular difficulties in identifying historical processes which drive species diversity and boundaries. Mechanisms causing discordance, such as incomplete lineage sorting or introgression due to interspecific hybridization, are better identified based on population-level genomic datasets. In the toads of the Rhinella granulosa species group, patterns of mito-nuclear discordance and potential hybridization have been reported by several studies. However, these patterns were proposed based on few loci, such that alternative mechanisms behind gene-tree heterogeneity cannot be ruled out. Using genome-wide ddRADseq loci from a subset of species within this clade, we found only partial concordance between currently recognized species-level taxon boundaries and patterns of genetic structure. While most taxa within the R. granulosa group correspond to clades, genetic clustering analyses sometimes grouped distinct taxonomic units into a single cluster. Moreover, levels of admixture between inferred clusters were limited and restricted to a single taxon pair which is best explained by incomplete lineage sorting as opposed to introgressive hybridization, according to D-statistics results. These findings contradict previous assertions of widespread cryptic diversity and gene flow within the R. granulosa clade. Lastly, our analyses suggest that diversification events within the Rhinella granulosa group mostly dated back to the early Pliocene, being generally younger than species divergences in other closely related clades that present high levels of cross-species gene flow. This finding uniquely contradicts common assertions that this young clade of toads exhibits interspecific hybridization. (AU)

Processo FAPESP: 03/10335-8 - Sistemática e evolução da herpetofauna neotropical
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Modalidade de apoio: Auxílio à Pesquisa - Temático
Processo FAPESP: 13/50297-0 - Dimensions US-BIOTA São Paulo: integrando disciplinas para a predição da biodiversidade da Floresta Atlântica no Brasil
Beneficiário:Cristina Yumi Miyaki
Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
Processo FAPESP: 11/50206-9 - Origem e evolução das serpentes e a sua diversificação na região neotropical: uma abordagem multidisciplinar
Beneficiário:Hussam El Dine Zaher
Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
Processo FAPESP: 17/08357-6 - Padrões de Endemismo Filogenético e Filogeografia Comparada da Herpetofauna da Amazônia Brasileira
Beneficiário:Sérgio Marques de Souza
Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
Processo FAPESP: 11/50146-6 - Filogeografia comparada, filogenia, modelagem paleoclimática e taxonomia de répteis e anfíbios neotropicais
Beneficiário:Miguel Trefaut Urbano Rodrigues
Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
Processo FAPESP: 12/15754-8 - Consequências ecogeográficas da evolução do morfotipo serpentiforme em Squamata
Beneficiário:Agustín Camacho Guerrero
Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado