A complex biogeographic history of diversification in Neotropical lancehead pitvipers (Serpentes, Viperidae)

Abstract

Based on literature, we had predicted that the diversification within the Neotropical snake genus Bothrops occurred along a latitudinal gradient from north to south, with diversification into unoccupied niches through ecological opportunity, not correlated with geoclimatic events. Using a dated phylogeny and estimating likelihoods of ancestral states at cladogenesis events, we reconstructed ancestral areas and assessed major events of the diversification of Bothrops clades, and we also discuss systematic implications for this group. Based on the phylogeny we produced, B. lojanus was not considered as part of the genus Bothrops since the results recovered this species nested within the Bothrocophias clade. We infer that the diversification of the Miocene B. pictus and B. alternatus clades may be related to the uplift of the western slopes of the Andes and the Argentinian Patagonian Andes, respectively. The Pliocene B. taeniatus and B. osbornei clades may be related to the uplift of the eastern and northern Andes, respectively. The Plio-Pleistocene B. neuwiedi clade may be related to the habitat transitions from a warmer and forested environment to a cooler and open landscape; the B. jararaca (i.e., island endemic species) and B. lanceolatus clades to over-water dispersal with island speciation; and B. atrox clade to the appearance of the Panamanian land bridge. We found a multitemporal and multidirectional history of diversification may be correlated with geoclimatic and dispersalist events. We argue that the vacant niche hypothesis by itself does not explain Bothrops diversification.