Cryptic diversity and biogeography of South American salamanders

Tropical regions harbor a majority of Earth’s biodiversity. In most taxonomic groups there is a gradient of increasing diversity from polar to tropical latitudes. In a few groups, however, the gradient is partly inverted and species richness peaks in temperate regions. One of those groups are salamanders, a group with higher diversity in North and Middle America than in tropical South America. This inverse gradient could result from a time for diversification effect because they arrived more recently to South America. However, an additional contributing factor could be that salamander diversity is underestimated in South America. In this study we used mitochondrial and nuclear DNA sequences to obtain a more comprehensive phylogeny of South American salamanders, to estimate their time of colonization of this continent and assess their species diversity. Using published and new genetic data, we generated a time-calibrated phylogeny and reconstructed ancestral bioregions and altitudes to infer the colonization history of Bolitoglossa in South America. The phylogenetic analyses recognized 19 candidate species, of which 13 are confirmed candidate species. This represents an increase of at least 38% in the species content of South American salamanders demonstrating that species richness is severely underestimated. Our results show that the ancestor of Bolitoglossa first colonized middle altitudes of the Andes, between the Oligocene and the Miocene. Therefore, all extant species descend from an Andean ancestor, which subsequently colonized higher and lower elevations. Our results suggest that salamander history has been closely linked to the Andean uplift and agrees with previous studies showing that most of the South American biodiversity diversified prior to the Quaternary. Our results show that the Andes have been a species pump for lowland regions. This highlights the importance of the protection of montane regions to maintain the processes that promote species diversification of this group of organisms. We show that formally described species with wide geographical distributions are in fact species complexes on which each species has small geographic ranges. Therefore, the extinction probability of South American salamanders it is likely to be underestimated under the IUCN’s Red List.

• Autor principal: Hervas Sotomayor, Francisca (author)
• Formato: masterThesis
• Publicado em: 2016
• Assuntos: Salamanders; Amphibians - Urodela; Phylogeny; Phylogenetic analysis; Biodiversity
• Acesso em linha: https://repositorio.puce.edu.ec/handle/123456789/21043