RESUMO
Speciation with gene flow often leads to ambiguous phylogenetic reconstructions, reticulate patterns of relatedness and conflicting nuclear versus mitochondrial (mt) lineages. Here we employed a fragment of the COI mtDNA gene and nuclear genome-wide data (3RAD) to assess the diversification history of Sphenarium, an orthopteran genus of great economic importance in Mexico that is presumed to have experienced hybridisation events in some of its species. We carried out separate phylogenetic analyses to evaluate the existence of mito-nuclear discordance in the species relationships, and also assessed the genomic diversity and population genomic structure and investigated the existence of interspecific introgression and species limits of the taxa involved based on the nuclear dataset. The species delineation analyses discriminated all the currently recognised species, but also supported the existence of four undescribed species. The mt and nuclear topologies had four discordant species relationships that can be explained by mt introgression, where the mt haplotypes of S. purpurascens appear to have replaced those of S. purpurascens A and B, S. variabile and S. zapotecum. Moreover, our analyses supported the existence of nuclear introgression events between four species pairs that are distributed in the Sierra Madre del Sur province in southeast Mexico, with three of them occurring in the Tehuantepec Isthmus region. Our study highlights the relevance of genomic data to address the relative importance of allopatric isolation versus gene flow in speciation.
Assuntos
Gafanhotos , Animais , Filogenia , Gafanhotos/genética , México , DNA Mitocondrial/genética , DNA Mitocondrial/química , Mitocôndrias/genéticaRESUMO
Abronia and Mesaspis are two of the five anguid lizard genera in the subfamily Gerrhonotinae. Their members are restricted to Mesoamerica, and most have allopatric distributions. Species of Abronia are primarily arboreal and occur in cloud and seasonally dry pine-oak forests, whereas those of Mesaspis are terrestrial and inhabit mesic microhabitats of montane forests. Recent molecular studies suggest that although these genera together form a monophyletic group, neither genus is monophyletic. Here we performed a phylogenetic study of Abronia and Mesaspis based on the most comprehensive taxonomic sampling of these genera to date and double digest restriction site-associated (ddRADseq) data. Our reconstructed phylogeny differed considerably from all previously published topologies, consistently recovering multiple independent clades of arboreal and terrestrial species and Abronia and Mesaspis as non-monophyletic. Geography, rather than current taxonomy, provides the best explanation of their phylogenetic relationships. Our analyses consistently recovered two main clades, distributed on the highlands of Middle America east and west of the Isthmus of Tehuantepec, respectively, and each composed of subclades of Abronia and Mesaspis. In the former main clade, members of the subgenus Auriculabronia formed the sister taxon to the Mesaspis moreletii complex, whereas the main clade west of the Isthmus was composed of two clades with a subclade of Abronia and another of Mesaspis each (one clade on the Atlantic versant of the main mountain ranges of eastern Mexico and another one on the Sierra Madre del Sur exclusive of its Atlantic versant) and a third clade with species of the subgenera Abronia and Scopaeabronia. We discuss the taxonomic implications of our results for the classification of the examined taxa and list the morphological characters that diagnose the recovered clades. This study highlights the utility of ddRADseq data to reconstruct the evolutionary history of supraspecific vertebrate taxa.
Assuntos
Jacarés e Crocodilos/classificação , Jacarés e Crocodilos/genética , Lagartos/classificação , Lagartos/genética , Filogenia , Animais , Sequência de Bases , Florestas , Loci Gênicos , Geografia , Homozigoto , Funções Verossimilhança , México , Análise de Sequência de DNA , Especificidade da EspécieRESUMO
Phylogeographic studies of continent-wide distributed species are key to understand population dynamics processes that occurred at large geographical scales. Here, we examined two mitochondrial (mt) DNA sequence (COI, Cyt b) and eight nuclear microsatellites markers to investigate the cohesiveness, genetic diversity and demographic history of Neoponera villosa (Fabricius), a ponerine ant species widely distributed along most part of the Neotropics and southern Nearctic. The reconstructed phylogeny and mt variation supported the cohesiveness of the examined populations of N. villosa. The species probably originated in South America during the late Pliocene/middle Pleistocene and subsequently dispersed to Central America and the Transitional Nearctic-Neotropical zone during the late Pleistocene, with an increase in its population size ca. 30 thousand years ago. The limited phylogeographic structure observed in N. villosa supports its late Pleistocene range expansion and gene flow among distant geographic areas in central and southern Mexico and Central America.