Browsing by Author "Palma, R. Eduardo"

Now showing 1 - 9 of 9
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    An updated biogeographic evaluation of endemism and conservation of small mammals from Chile
    (2023) Hernandez-Mazariegos, Wendy C.; Ibanez, Christian M.; Palma, R. Eduardo
    Ecological factors such as temperature, precipitation, and vegetation type have been reported to influence biogeographic patterns (e.g., species distribution, richness, and endemism) in mammals. In Chile, these patterns only had been explored in selected mammal groups from certain localities. In this study, we describe and analyze biogeographic patterns for all small mammals (marsupials, armadillos, bats, rodents), reported until 2020, in different climatic and ecological regions from continental Chile. Using a compiled database of 89 species, we estimated their distributional similarity, described and characterized richness and areas of endemism using Bayesian and Parsimony Analysis of Endemism, and linked species distribution with conservation status according to the IUCN Red List. We found three similarity units of species distribution based on climate: Arid, Temperate, and Polar; higher richness and endemism in north and south-central Chile; two areas of endemism, one in north and one in south; and a hotspot in south-central Chile. Finally, species of greater conservation concern showed a similar and small distribution range. The concordance in the distribution of the species with Chilean climatic regions (as determined by precipitation and temperature) suggest that the spatial distribution of Chilean small mammals is influenced strongly by those abiotic factors. This also could explain the patterns of richness and endemism and, therefore species hotspots. Variations of climatic factors therefore should be considered in explaining biogeographic patterns and conservation plans of Chilean small mammal species, because species of greater concern tend to be associated and having similar distributional characteristics.
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    Assessing Ecogeographic Rules in Two Sigmodontine Rodents along an Elevational Gradient in Central Chile
    (2024) Valladares-Gomez, Alejandro; Torres-Perez, Fernando; Palma, R. Eduardo
    Simple Summary Two ecogeographic rules predict morphological changes along latitudinal clines based on thermoregulatory causes. To maintain corporal heat in cold environments (higher latitudes), larger body sizes and shorter appendages and limbs are predicted by Bergmann's and Allen's rules, respectively. Both rules may also apply to elevational gradients, due to the decrease in external temperature as elevation increases. We evaluated whether these ecogeographic rules were true in two rodent species across an elevational gradient in central Chile. The species studied were Abrothrix olivacea and Phyllotis darwini, which coexist across this altitudinal range. Our results showed a low support for these rules, as well as an opposite body size trend between both species. Other than morphology, physiological and behavioral strategies could be more critical to thermoregulating in high, montane environments, and new hypotheses should be tested to explain the morphological changes that we observed in this study.Abstract Bergmann's and Allen's rules are two classic ecogeographic rules concerning the physiological mechanisms employed by endotherm vertebrates for heat conservation in cold environments, which correlate with adaptive morphological changes. Thus, larger body sizes (Bergmann's rule) and shorter appendages and limbs (Allen's rule) are expected in mammals inhabiting cold environments (higher latitudes). Both rules may also apply to elevational gradients, due to the decrease in external temperature as elevation increases. In this study, we evaluated whether these patterns were true in two coexisting sigmodontine rodents across an elevational gradient in central Chile. We analyzed whether the size of the skull, body, and appendages of Abrothrix olivacea (n = 70) and Phyllotis darwini (n = 58) correlated with elevation, as predicted by these rules in a range between 154 and 2560 m. Our data revealed weak support for the Bergmann and Allen predictions. Moreover, we observed opposite patterns when expectations of Bergmann's rules were evaluated, whereas Allen's rule just fitted for ear size in both rodent species. Our results suggest that morphological changes (cranial, body, and appendage sizes) may play a minor role in the thermoregulation of these two species at high elevations, although behavioral strategies could be more critical. Other ecological and environmental variables could explain the morphological trends observed in our study. These hypotheses should be assessed in future studies to consider the relative contribution of morphology, behavior, and physiological mechanisms to the thermal adaptation of these two rodent species at high elevations.
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    Mitochondrial DNA variation and systematics of the guanaco (Lama guanicoe, Artiodactyla: Camelidae)
    (2008) Marin, Juan C.; Spotorno, Angel E.; Gonzalez, Benito A.; Bonacic, Cristian; Wheeler, Jane C.; Casey, Ciara S.; Bruford, Michael W.; Palma, R. Eduardo; Poulin, Elie
    Guanacos (Lama guanicoe) are the most important native herbivorous species in the South American steppes and the dominant ungulate in a fauna rich in rodents but poor in large mammal species. Between 2 and 4 subspecies are usually recognized within Lama guanicoe, based on subtle morphological differences and geographic distribution. To evaluate whether molecular variation is consistent with the latter hypotheses, we analyzed the complete cytochrome-b and partial control region mitochondrial DNA sequences of L. guanicoe from 22 localities in Peru, Bolivia, Argentina, and Chile. Sequence analyses of both genes support the monophyly of the species but failed to distinguish the occurrence of subspecies along the geographic range. Despite that, the northernmost populations (Peru and northern Chile) showed some degree of genetic differentiation with respect to southern representatives from Argentina, Bolivia, and rest of Chile. Analysis of genetic diversity also showed a strong signal of past low population size and a recent population expansion.
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    Molecular phylogeography of Abrothrix olivaceus (Rodentia: Sigmodontinae) in Chile
    (2006) Rodriguez-Serrano, Enrique; Cancino, Ricardo A.; Palma, R. Eduardo
    Abrothrix olivaceus is the most abundant and widespread species of sigmodontine rodent in Chile. We evaluated phylogeographic relationships within A. olivaceous based on analyses of 67 specimens collected along most of the distributional range of the species. We used nucleotide sequence data from the hypervariable domain I of the mitochondrial DNA control region. Examination of our data supports a northern origin for this taxon, followed by southward dispersal. Also, we propose the occurrence of a new subspecies of A. olivaceus in the northernmost limit of the species' range. We detected a significant influence of recent paleoclimatic events on the current distribution of A. olivaceus, particularly in south-central Chile. The results also support the genetic distinctness of nominal subspecies proposed in the classical literature.
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    Molecular systematics of chinchilla rats and taxonomic assessment of the Abrocoma cinerea species complex
    (2024) Gonzalez-Pinilla, Francisco J.; Latorre, Claudio; Palma, R. Eduardo
    Chinchilla rats (family Abrocomidae) are hystricomorph rodents primarily inhabiting the central Andes in South America with 8 species in the genus Abrocoma and 2 in Cuscomys. The systematics of this family-relying only on morphological differences-has faced several controversies, particularly in arid-adapted species of Abrocoma (the A. cinerea species complex, or ACC). By using partial DNA sequences of 1 mitochondrial (Cytochrome b) and 2 nuclear genes (GHR and RAG1), we: (i) inferred phylogenetic relationships between 5 species of Abrocoma and 1 of Cuscomys; (ii) performed molecular species-delimitation analyses in 4 species of the ACC (A. cinerea, A. famatina, A. schistacea, and A. uspallata); and (iii) estimated divergence times using stratigraphic ages of extinct taxa. Our phylogenetic analyses recovered 3 main clades: A. bennettii (basal); C. ashaninka; and the ACC. Striking differences in habitat use, morphology, and genetics suggest that each of these main clades might represent a distinct genus. In species-delimitation analyses in the ACC, only 2 species were recognized, and we thus suggest the synonymy of A. famatina with A. cinerea and of A. uspallata with A. schistacea. The origin of extant abrocomids was estimated at the late Miocene (similar to 5.6 million years ago, Ma) with the subsequent origin of arboreal species during the early Pliocene (similar to 4.3 Ma) and the ACC during the late Pliocene (similar to 3.3 Ma). We hypothesize that topographic uplift of the central Andes and associated climatic and ecological changes were the main drivers of diversification in this family.
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    Near-shore distribution of phyllosomas of the two only lobster species (Decapoda: Achelata) present in Robinson Crusoe Island and endemic to the Juan Fernandez archipelago
    (SOC BIOLGIA CHILE, 2011) Palma, Alvaro T.; Caceres Montenegro, Ismael; Bennett, Richard S.; Magnolfi, Spartaco; Henriquez, Luis A.; Guerra, Jorge F.; Manriquez, Karen; Palma, R. Eduardo
    Two lobster species coexist in the southeast Pacific Juan Fernandez archipelago, Jasus frontalis (Milne-Edwards, 1837) and Acantharctus delfini (Bouvier, 1909). Like most lobster species they undergo a prolonged larval period, which is particularly long for J. frontalis (> 16 months). Though typical of Palinurids, this long larval duration is usually not thought to be conducive to local recruitment. While it is known that settlement is confined to the three islands of the archipelago (Robinson Crusoe, Alejandro Selkirk and Santa Clara) and Desventuradas Islands (aprox. 800 km to the north), it remains poorly understood how local larval supply allows such distribution pattern. The goal of this study is twofold. Firstly, we aimed to characterize the distribution and abundance of the larvae of these two species around Robinson Crusoe Island using plankton tows and systematic hydrographic records between October 2008 to March of 2011, thus providing the first systematic and prolonged coupled biophysical observations in the nearshore of the archipelago. We hypothesize that spatial and temporal larval distribution patterns are associated to their retention around the archipelago, thus contributing to our knowledge of the physical and biological processes maintaining their extreme isolation. Secondly, using molecular genetics, we confirm a simple taxonomic criteria to distinguish the larvae of the two species, thus aiding future studies of larval dynamics. Throughout phyllosomas of A. delfini were more abundant than that of J. frontalis. Both species were more abundant on the northern shores of Robinson Crusoe Island and generally associated with warmer and saltier waters and mostly present in the samples collected during spring and summer months. Phyllosomas of both species were more abundant during night-time tows in the upper layer of the water column surveyed suggesting a diurnal vertical migration behavior which, for coastal dwelling meroplanktonic species, can be related to a nearshore larval retention mechanism. These preliminary results represent a pioneering effort to understand the mechanisms driving the endemism and extreme isolation of the two study species.
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    Phylogeography of the subterranean rodent Spalacopus cyanus (Caviomorpha, Octodontidae)
    (ALLIANCE COMMUNICATIONS GROUP DIVISION ALLEN PRESS, 2008) Opazo, Juan C.; Bugueno, Manuel P.; Carter, Mauricio J.; Palma, R. Eduardo; Bozinovic, Francisco
    Spalacopus cyanus is a subterranean rodent inhabiting coastal and mountain habitats. Individuals from mountain populations are larger than individuals from the coast, and mountain populations have a more limited geographic range. To investigate the genetic structure and biogeography of this species, we analyzed mitochondrial DNA control region sequences. We found low levels of nucleotide diversity in comparison with other subterranean rodents. Coastal populations had higher nucleotide diversity and effective population size than mountain populations. Phylogenetic analysis using maximum parsimony and a haplotype network generated using statistical parsimony recognized 3 groups of haplotypes: northern coastal and mountain populations, central coastal populations, and southern coastal population. Consistent with the presence of unshared haplotypes, migration rates were practically 0, except from Valparaiso to Ventanas and from La Parva to Huentelauquen. We observed asymmetric migration rates from mountain to coastal populations, suggesting that this species originated in the Andean mountains. A likelihood ration test could not reject the null hypothesis of a stable population when all sequences were grouped into a single population and when coastal populations were analyzed separately. However, a negative exponential growth parameter was estimated for mountain populations,suggesting that these populations have undergone recent demographic changes.
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    Systematics and evolutionary relationships of the mountain lizard Liolaemus monticola (Liolaemini): how morphological and molecular evidence contributes to reveal hidden species diversity
    (2009) Torres-Perez, Fernando; Mendez, Marco A.; Benavides, Edgar; Moreno, Rodrigo A.; Lamborot, Madeleine; Palma, R. Eduardo; Ortiz, Juan Carlos
    The delimitation of species is a major issue in systematic biology and has been a re-emerging discipline in the last decade. A number of studies have shown that the use of multiple data sets is critical for the identification of cryptic species, particularly in groups with complex evolutionary histories. Liolaemus monticola is a montane lizard species distributed in central Chile (32 degrees-42 degrees S), with four described subspecies in a latitudinal gradient from north to south: L. m. monticola, L. m. chillanensis, L. monticola ssp. and L. m. villaricensis. In order to test the systematic status and phylogenetic relationships of the taxa included in the L. monticola group, we analysed morphological (morphometric and meristic) and molecular (allozyme and mitochondrial DNA) data sets. The results of the morphological analyses showed that meristic variables correctly assigned individuals with higher accuracy than did morphometric characters. The results of the analyses of allozyme data revealed eight diagnostic loci that are evidence for significant differences among the four L. monticola subspecies. Phylogenetic analyses with mitochondrial DNA data, including additional species, showed that the L. monticola group is polyphyletic. We postulate that the four current subspecies represent independent evolutionary lineages and must be raised to the specific level as L. monticola, L. chillanensis and L. villaricensis. The taxonomic status of the unnamed L. monticola ssp. remains unresolved, although we provide a preliminary proposal. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 635-650.
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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.