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 sal...
| Autor Principal: | Hervas Sotomayor, Francisca |
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| Formato: | Master Thesis |
| Idioma: | English |
| Publicado: |
PUCE
2017
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| Materias: | |
| Acceso en línea: |
http://repositorio.puce.edu.ec/22000/13023 |
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| Sumario: |
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. |
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