Browsing by Author "Veloso, Alberto"

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    Genetic and Reproductive Evidence of Natural Hybridization between the Sister Species Rhinella atacamensis and Rhinella arunco (Anura, Bufonidae)
    (2012) Correa, Claudio L.; Mendez, Marco A.; Veloso, Alberto; Sallaberry, Michel
    Rhinella atacamensis and Rhinella arunco are sister species which, together, are distributed from 25 degrees S to 38 degrees S in Chile. Until recently they were considered to be allopatric, with the dividing line around 32 degrees S, but in 2007 a possible zone of secondary contact was found in the Estero Pupio (32 degrees S). We investigated the species status of adult individuals of three localities along this creek using AFLP markers. Data were analyzed with a Bayesian method that allowed the identification of different types of hybrids in a population. In two of the localities in the lower part of the watershed, the majority of the individuals were identified as backcrosses of hybrids with R. arunco or first generation hybrids, although a few individuals were classified as pure R. arunco. This information, supplemented by mitochondrial sequences and reproductive observations in both the laboratory and in the field, shows that hybridization has been a recurrent phenomenon at these two localities. By contrast, in the third locality, higher in the watershed, we detected a certain amount of nuclear introgression of R. arunco in a population where Only individuals with phenotypes and mitochondrial genotypes of R. atacamensis were found. Taken together, the genetic data of the three localities suggest that the hybrid zone is a hybrid swarm which is relatively extensive in the watershed of the creek. Identifying the causes of the apparent spatial segregation of the two species in the Estero Pupio will require additional information.
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    Genetic divergence in the endangeredfrog Insuetophrynus acarpicus (Anura: Leptodactylidae)
    (2006) Mendez, Marco A.; Torres-Perez, Fernando; Correa, Claudio; Soto, Eduardo R.; Nunez, Jose J.; Veloso, Alberto; Armesto, Juan
    Insuetophrynus acarpicus is a poorly known frog restricted to the temperate forests of the coastal range of Chile (39 degrees 25' S, 73 degrees 10' W). Until recently, this species was known only from one type locality since its original description in 1970. However, in 2002 two new localities were reported, extending its distribution range to about 40 km(2). In order to evaluate genetic divergence, provide a preliminary evaluation of the genetic diversity of this species and the phylogenetic relationships among individuals from the three known populations, we analyzed the nucleotide variation of a fragment of the mitochondrial gene cytochrome b. We sampled just two or four individuals per population of this endangered frog. We found a low nucleotide divergence among populations suggesting a genetic homogeneity across the entire range. This highlights the need for further studies to define the conservation status of this endangered frog.
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    Phylogeography of Rhinella spinulosa (Anura: Bufonidae) in northern Chile
    (2010) Correa, Claudio; Pastenes, Luis; Sallaberry, Michel; Veloso, Alberto; Mendez, Marco A.
    The southern part of the Altiplano of the Andes Range is characterized by a complex hydrography, due to an intense geologic activity and the effects of the Pleistocene glaciations. This has produced a high degree of diversity at the species level in some aquatic taxa (e. g., fish and amphibians), which suggests that these same processes have produced divergence at the intraspecific level in co-distributed taxa. We investigated the genetic variation in populations of the anuran Rhinella spinulosa which represent its entire distribution in the extreme north of Chile (17 degrees 44'S-23 degrees 47'S). Haplotype networks of the mitochondrial control region recognized two main lineages, one of which is distributed from the northern boundary of Chile to the Salar de Alconcha and the other from the Salar de Carcote to the locality of Tilomonte. The northern lineage showed little phylogeographic structure; a few very frequent haplotypes are widely distributed. The southern lineage had greater structure, due principally to the high divergence of the populations from the eastern springs of the Salar de Atacama. Fu's Fs test and the mismatch distributions suggested that most of the populations of both lineages are in the process of demographic expansion. The spatial distribution of the genetic variability was correlated with the hydrography and the paleoclimatological data available for the region, which suggested that geographic expansions followed by periods of contraction of population ranges, together with sporadic floods may explain the observed phylogeographic patterns.