Browsing by Author "Zeballos, Horacio"

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    Phylogenetic relationships of the pygmy rice rats of the genus Oligoryzomys Bangs, 1900 (Rodentia: Sigmodontinae)
    (OXFORD UNIV PRESS, 2010) Eduardo Palma, R.; Rodriguez Serrano, Enrique; Rivera Milla, Eric; Hernandez, Cristian E.; Salazar Bravo, Jorge; Carma, Maria I.; Belmar Lucero, Sebastian; Gutierrez Tapia, Pablo; Zeballos, Horacio; Yates, Terry L.
    Sequences from two mitochondrial genes (cytochrome b and NADH1) were used to produce a molecular phylogeny for 12 named and two undescribed species of the genus Oligoryzomys. All analyses placed Oligoryzomys microtis as the most basal taxon, a finding consistent with previous studies that suggested the west-central Amazon as a centre of origin for the tribe Oryzomyini to which Oligoryzomys belongs. Biogeographically, this suggests that Oligoryzomys had a South American origin, and later advanced northwards, entering Central America and Mexico more recently. Different analyses have provided consistent support for several additional clades that did not necessarily agree with the species groups hypothesized by previous studies. A molecular clock derived for these data suggests an origin for the genus of 6.67 Mya, with most speciation within the genus occurring between 3.7 and 1.5 Mya. © 2010 The Linnean Society of London.
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    Phylogeography of the Marine Otter (Lontra felina): Historical and Contemporary Factors Determining Its Distribution
    (2010) Vianna, Juliana A.; Ayerdi, Paula; Medina-Vogel, Gonzalo; Mangel, Jeffrey C.; Zeballos, Horacio; Apaza, Manuel; Faugeron, Sylvain
    The evolutionary history of a species can be revealed by phylogeographical analysis; nevertheless, not only historical but also contemporary processes can imprint on the distribution of genetic diversity. We report on the phylogeny of Lontra ssp. in South America, and the role of spatial heterogeneity in shaping the distribution and population structure of the endangered marine otter, Lontra felina. Analyzing a total of 2261 bp of mitochondrial DNA (mtDNA) revealed the recent divergence of L. felina from L. provocax. A strong population structure (Phi(st) = 0.83, P < 0.0001) and a significant pattern of isolation by distance were described for L. felina (n = 168) across a wide geographical distribution (13 degrees 53'S to 43 degrees 36'S). Lontra felina mtDNA phylogeny is composed of 2 main clades: a clade from Peru and another composed of Chilean haplotypes. Northern populations show different divergent lineages and higher genetic diversity when compared with more recently colonized southern populations. Furthermore, long sandy beaches seem to act as barriers to dispersal, creating 2 evolutionary significant units in agreement with subspecies previous description, and at least 5 different management units (MUs). At a fine spatial scale, the size of rocky seashore patches, the distance between patches and anthropogenic factors also play important roles in species gene flow.