Browsing by Author "Hernandez, Cristian E."

Now showing 1 - 7 of 7
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    Genetic identification of benthic polychaetes in a biodiversity hotspot in the southeast Pacific
    (2011) Canales-Aguirre, Cristian B.; Rozbaczylo, Nicolas; Hernandez, Cristian E.
    The aim of this study was to evaluate the utility of COI, of the mitochondrial DNA, for the taxonomic determination of soft-bottom benthic polychaetes in the Chiloe Inner Sea as a particularly important zone for polychaete fauna of the southeast Pacific. The results show high genetic differentiation between morphological species of polychaetes (posterior probabilities upper 0.9), and Onuphis pseudoiridescens showed the greatest divergence (3.08 +/- 0.08 S. D.). The results support the role of the COI gene as a useful molecular marker for fast and accurate taxonomic determination of benthic polychaetes. This study leads the way for research on the biodiversity and systematics of polychaetes off the Chilean coast using molecular phylogenetic criteria.
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    Glaciation Effects on the Phylogeographic Structure of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae) in the Southern Andes
    (2012) Eduardo Palma, R.; Boric-Bargetto, Dusan; Torres-Perez, Fernando; Hernandez, Cristian E.; Yates, Terry L.
    The long-tailed pygmy rice rat Oligoryzomys longicaudatus (Sigmodontinae), the major reservoir of Hantavirus in Chile and Patagonian Argentina, is widely distributed in the Mediterranean, Temperate and Patagonian Forests of Chile, as well as in adjacent areas in southern Argentina. We used molecular data to evaluate the effects of the last glacial event on the phylogeographic structure of this species. We examined if historical Pleistocene events had affected genetic variation and spatial distribution of this species along its distributional range. We sampled 223 individuals representing 47 localities along the species range, and sequenced the hypervariable domain I of the mtDNA control region. Aligned sequences were analyzed using haplotype network, Bayesian population structure and demographic analyses. Analysis of population structure and the haplotype network inferred three genetic clusters along the distribution of O. longicaudatus that mostly agreed with the three major ecogeographic regions in Chile: Mediterranean, Temperate Forests and Patagonian Forests. Bayesian Skyline Plots showed constant population sizes through time in all three clusters followed by an increase after and during the Last Glacial Maximum (LGM; between 26,000-13,000 years ago). Neutrality tests and the "g" parameter also suggest that populations of O. longicaudatus experienced demographic expansion across the species entire range. Past climate shifts have influenced population structure and lineage variation of O. longicaudatus. This species remained in refugia areas during Pleistocene times in southern Temperate Forests (and adjacent areas in Patagonia). From these refugia, O. longicaudatus experienced demographic expansions into Patagonian Forests and central Mediterranean Chile using glacial retreats.
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    Morphological and molecular characterization of Perinereis gualpensis (Polychaeta: Nereididae) and its phylogenetic relationships with other species of the genus off the Chilean coast, Southeast Pacific
    (2013) Sampertegui, Sandra; Rozbaczylo, Nicolas; Canales-Aguirre, Cristian B.; Carrasco, Franklin; Hernandez, Cristian E.; Rodriguez-Serrano, Enrique
    The genus Perinereis, family Nereididae, consists of approximately 66 worldwide distributed species with marine, estuarine, and freshwater representatives. The objective of this study is to use morphological and molecular traits to evaluate the taxonomic differentiation of the estuarine polychaete P gualpensis. Also we reconstruct the phylogenetic relationships between P gualpensis and congeneric species recorded in Chilean coast: P. falklandica, P. longidonta and, especially with the morphologically most similar species, P vallata. Phylogenetic analyses based on molecular and morphological characters allow us to validate P. gualpensis and P. vallata as two independent and clearly defined species. Consequently, the taxonomic confusion about the possible sibling species P. gualpensis and P. vallata is completely resolved. However, morphological and genetic data are partially incongruent about the phylogenetic relationships of these four Perinereis species. We concluded that different evolutionary process that affect the morphological and genetics data produce different answers. Also we propose the use of new molecular evidence arising from molecular markers with different nucleotide substitution rate to that used here.
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    Phylogenetic evaluation of taxonomic definition of didelphid mouse opossum of the genus Thylamys from valleys of Coquimbo region, Chile
    (2016) Boric-Bargetto, Dusan; Zuniga-Reinoso, Alvaro; Cancino, Ricardo A.; Gonzalez-Acuna, Daniel; Rodriguez-Serrano, Enrique; Eduardo Palma, R.; Hernandez, Cristian E.
    Only two species of Didelphidae are currently recognized in Chile, the sister species Thylamys elegans, endemic of Mediterranean ecorregion and Thylamys pallidior, the inhabitant of the Puna and desert canyons. Three subspecies have been described for T. elegans: T. e. elegans, T. e. coquimbensis and T. e. soricinus. However, a recent study based on morphological analyses, synonymized T. elegans coquimbensis from the Coquimbo valleys (30-31 degrees S) with T. pallidior and proposed that T. elegans and T. pallidior could be in sympatry at Coquimbo valleys between Fray Jorge (30 degrees 40'S) and Paiguano (30 degrees 02'S). We assess the current definition of T. e. coquimbensis and T. e. elegans, as well as this taxonomical conflict among the mouse opossums from the Coquimbo valleys through phylogenetic analyses of cytochrome b mitochondrial gene sequences. In this study, for the first time, we used specimens from the type localities of T. e. coquimbensis and T. e. elegans. In addition, we analyzed diagnostic cranial structures for this taxonomic revision. The results supported two allopatric clades, allowing us to keep the taxonomic definition of T. e. elegans and T. e. coquimbensis as phylogenetic reciprocal monophyletic clades and polyphyletic with T. pallidior. This result corroborates previous morphological analyses, which support that mouse opossums from the Coquimbo valleys are T. e. coquimbensis, thus extending its geographic distribution to the coast of Coquimbo and Atacama regions. We don't have evidence for sympatric distribution between T. elegans and T. pallidior in the Coquimbo region.
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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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    The importance of the Andes in the evolutionary radiation of Sigmodontinae (Rodentia, Cricetidae), the most diverse group of mammals in the Neotropics
    (2023) Vallejos-Garrido, Paulo; Pino, Kateryn; Espinoza-Aravena, Nicolas; Pari, Alexander; Inostroza-Michael, Oscar; Toledo-Munoz, Macarena; Castillo-Ravanal, Boris; Romero-Alarcon, Viviana; Hernandez, Cristian E.; Palma, R. Eduardo; Rodriguez-Serrano, Enrique
    The Andean mountains stand out for their striking species richness and endemicity that characterize many emblematic Neotropical clades distributed in or around these mountains. The radiation of the Sigmodontinae subfamily, the most diversified mammalian group in the Neotropics, has been historically related to Andean orogenesis. We aim to evaluate this interplay between geological processes and biological responses through the diversification dynamics, the biogeographical history, and the range evolution of the subfamily. For these, we built the most comprehensive phylogeny and gathered 14,836 occurrences for the subfamily. We identified one shift in the speciation rate in the genus Akodon, which suffered their Andean radiation after the arrival of non-Andean ancestors. Our biogeographic analyses show multiple dispersal paths throughout the evolution that allowed this subfamily to colonize all Neotropics. The Northern Andes and Central-Southern Andes were the most important sources of diversity. In addition, the Central-Southern Andes were the most relevant sink, receiving the highest number of lineages. The Andean region exhibited higher speciation and turnover rates than non-Andean regions. Thus, our results support the crucial role of the Andean Mountains in the Sigmodontinae radiation, acting as a "macroevolutionary cradle" and "species attractor" for several sigmodontine lineages at different times, and as a "species pump" becoming the biogeographic source of multiple widely distributed neotropical lineages. Then, complex macroevolutionary dynamics would explain these rodents' high extant Andean diversity and their wide distribution in the Neotropics.
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    Thorson's rule, life-history evolution, and diversification of benthic octopuses (Cephalopoda: Octopodoidea)
    (2018) Ibanez, Christian M.; Rezende Landaeta, Enrico; Sepulveda, Roger D.; Avaria-Llautureo, Jorge; Hernandez, Cristian E.; Sellanes, Javier; Poulin, Elie; Cecilia Pardo-Gandarillas, M.