Browsing by Author "Vianna, Juliana A."

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    A noninvasive sampling method for genetic analysis of the West Indian manatee (Trichechus manatus)
    (2009) Muschett Rivera, Giselle Elena; Bonacic Salas, Cristián; Vianna, Juliana A.
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    Molecular divergence between insular and continental Pudu deer (Pudu puda) populations in the Chilean Patagonia
    (TAYLOR & FRANCIS LTD, 2011) Fuentes Hurtado, Marcelo; Marin, Juan C.; Gonzalez Acuna, Daniel; Verdugo, Claudio; Vidal, Fernando; Vianna, Juliana A.
    Island-continent isolation scenarios have played major roles in the understanding and development of evolutionary theories. During the last glacial maximum (LGM) in southern Chile, ice sheet advances and retreats formed the Patagonian archipelago along the southern Pacific Ocean. Chiloe Island is the largest island from the archipelago isolated from the continent by a narrow and shallow stretch of ocean. Pudu puda is a species endemic to Chile and part of Argentina, distributed along the Valdivian Temperate rainforest. We used mtDNA control region (654 bp) and cytochrome b (734 bp) sequences to understand the consequences in the evolutionary history and population structure of Pudu puda island-continent isolation. Bayesian and Maximum Likelihood phylogenetic analysis revealed two divergent clades corresponding to the continent and Chiloe Island. The Median Joining Network also supports these findings with an isolation of 10 mutational steps between Chiloe and the continent. We also found a significant high genetic structure (phi st = 0.75) and a sequence divergence percentage of 2.3% between the two clades. On the other hand, on the continent we found high haplotype genetic diversity (H = 0.9790 +/- 0.0103) but no clear geographical population structure or phylogenetic clades. Our results suggest that the southern Pudu deer populations were isolated since the interglacial period (less than 0.5 million years ago) from the continent leading to two reciprocally monophyletic clades. We propose two subspecies to be considered in the development of future conservation programs for the species.
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    Phylogeography and Demographic History of the Neotropical Otter (Lontra longicaudis)
    (OXFORD UNIV PRESS INC, 2012) Trinca, Cristine S.; de Thoisy, Benoit; Rosas, Fernando C. W.; Waldemarin, Helen F.; Koepfli, Klaus Peter; Vianna, Juliana A.; Eizirik, Eduardo
    The Neotropical otter (Lontra longicaudis) is a medium-sized semiaquatic carnivore with a broad distribution in the Neotropical region. Despite being apparently common in many areas, it is one of the least known otters, and genetic studies on this species are scarce. Here, we have investigated its genetic diversity, population structure, and demographic history across a large portion of its geographic range by analyzing 1471 base pairs (bp) of mitochondrial DNA from 52 individuals. Our results indicate that L. longicaudis presents high levels of genetic diversity and a consistent phylogeographic pattern, suggesting the existence of at least 4 distinct evolutionary lineages in South America. The observed phylogeographic partitions are partially congruent with the subspecies classification previously proposed for this species. Coalescence-based analyses indicate that Neotropical otter mitochondrial DNA lineages have shared a rather recent common ancestor, approximately 0.5 Ma, and have subsequently diversified into the observed phylogroups. A consistent scenario of recent population expansion was identified in Eastern South America based on several complementary analyses of historical demography. The results obtained here provide novel insights on the evolutionary history of this largely unknown Neotropical mustelid and should be useful to design conservation and management policies on behalf of this species and its habitats.