Phylogeography and species delimitation of the Neotropical frog complex (Hylidae: Scinax granulatus)

Understanding which factors driving the genetic structure, geographic distribution patterns, and divergence of populations/species are of great interest in ecology and evolutionary biology. Phylogeographic and species hypotheses combined to distribution models may elucidate which phenomena drove evolutionary history of the biota of different biomes and ecoregions. Herein, we used distribution, environmental and genetic data to shed light on the evolutionary diversity of the Scinax granulatus complex, exploring the phylogeographic patterns, genetic structure and species boundaries across the Pampa and Southern Atlantic Forest biomes. We recovered four mitochondrial lineages which correspond to two putative species within the S. granulatus complex. We used genetic data to define species hypothesis with three discovery methods: bGMYC, bPTP and ASAP, and two delimitation approaches: BPP and BPP + gdi. We validated the species boundaries, confirming the differentiation of Scinax sp. lineage D from Atlantic Forest lowlands habitats, based on genetic data, ecological divergence and monophyly. Lineage D exhibited niche differentiation from S. granulatus sensu stricto (s.s.) based on distribution and environmental data. The climatic suitability of S. sp. D is defined by thermal variables, while that of S. granulatus s.s. was associated with rainfall. The diversification of the S. granulatus complex began during the Pliocene, but the colonization and divergence of lineages took place more recently during the Pleistocene. This study strongly suggests species-level evolutionary divergence among lineages of S. granulatus complex, and highlights the need to carry out a comprehensive evaluation of diagnostic characters to confirm the lineage D as a distinct species.