Browsing by Author "Valladares, Moises A."

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    A geometric morphometrics and genetics characterization of Vanessa carye in an extreme elevational gradient in the Chilean Altiplano
    (2023) Escobar-Suarez, Scott; Villalobos-Leiva, Amado; Fabres, Alejandra; Ordenes-Claveria, Rodrigo; Cruz-Jofre, Franco; Laroze, David; Correa, Margarita; Valladares, Moises A.; Caceres, Juan Sebastian D.; Benitez, Hugo A.
    The Western Painted Lady butterfly, Vanessa carye (Huber, 1812), in addition to pre-senting an extensive distribution in South America, has been observed flying in the Chilean Alti-plano from the coast to the highlands, from 0 to 5200 m.a.s.l. and it is suggested that could be a migratory insect. Some animal species move from one place to another by migration searching for favorable conditions. Wings of flying migratory animals are the principal trait involved in move-ment, and their shape has been documented to change between migratory and non-migratory species or populations. In this sense, little is known about the adaptations of butterflies to elevational gradients, so the V. carye's wide latitudinal and altitudinal range coupled with the different climatic conditions makes this species an interesting subject for adaptation studies. This research studies V. carye at different elevational ranges in extreme environments at the Chilean Altiplano and Atacama Desert to determine the presence of morphotypes through geometric morphometrics associated with altitudinal patterns, and to determine the genetic diversity and population structure of this species by using COI molecular marker. Subtle morphometric changes between populations were found, so two morphometric lineages were defined: a "coastal" lineage with more elongated wings and an "altiplano" lineage with more rounded wings. Nevertheless, low genetic diversity and no genetic structure associated to these morphological differences were found. Understanding the processes underlying the wing shape of V. carye morphological adaptations will help to understand its natural history. Results here may be a first approach of evidence to answer the question "Is this butterfly a migratory species?"
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    Ancient diversification in extreme environments: exploring the historical biogeography of the Antarctic winged midge Parochlus steinenii (Diptera: Chironomidae)
    (2024) Maturana, Claudia S.; Mejias, Tamara Contador; Simoes, Felipe L.; Valladares, Moises A.; Vidal, Paula M.; Ganan, Melisa; Gonzalez-Wevar, Claudio A.; Poulin, Elie; Sands, Chester J.; Convey, Peter
    The terrestrial fauna of Antarctica consists of a limited number of species, notably insects, small crustaceans and other micro-invertebrates. Over long periods of evolutionary isolation, these organisms have developed varying degrees of tolerance to multifaceted environmental stresses. Recent molecular biogeographical research highlights the enduring persistence of much of Antarctica's current terrestrial fauna, with estimates spanning from hundreds of thousands to millions of years. Parochlus steinenii, commonly known as the Antarctic winged midge, stands out as one of the only two insect species native to Antarctica. Distributed across three biogeographic regions, southern South America and the Falkland/Malvinas Islands, sub-Antarctic South Georgia and the Maritime Antarctic South Shetland Islands, this midge raises questions about the temporal isolation of its populations and their divergence. Employing mitochondrial and nuclear genetic markers, we conducted phylogeographic and demographic analyses on 151 individuals of P. steinenii obtained across the three main biogeographic regions including the Magellanic sub-Antarctic Ecoregion (MSE) of southern South America, the sub-Antarctic Island of South Georgia (SG) and the South Shetland Islands (SSI) within the Maritime Antarctic (MA). Our data support the diversification of P. steinenii during the mid-Pleistocene around 1.46 Mya. This period included a branching event between a clade containing only specimens from the MSE and a clade containing individuals from a broader range of locations including the SSI and SG. Based on intraspecific phylogeographic and demographic inferences, we detected strong evolutionary divergence between the three main biogeographic regions. We also detected a signal of population growth during the deglaciation process in SSI and SG, contrary to the pattern seen in the MSE. The different demographic and phylogeographic histories between the sampled biogeographic regions could result from the MA and SG experiencing a strong genetic bottleneck due to a reduction in population size during the Last Glacial Maximum, while the MSE maintained a significant effective population size. The high level of divergence detected between individuals from the MSE and the remaining biogeographic regions supports the hypothesis of a speciation process taking place in P. steinenii.
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    Coping With Dynamism: Phylogenetics and Phylogeographic Analyses Reveal Cryptic Diversity in Heleobia Snails of Atacama Saltpan, Chile
    (2022) Valladares, Moises A.; Fabres, Alejandra A.; Collado, Gonzalo A.; Saez, Paola A.; Mendez, Marco A.
    The species that inhabit systems highly affected by anthropic activities usually exhibit this external influence in their gene pool. In this study, we investigated the genetic patterns of populations of Heleobia atacamensis, a freshwater microgastropod endemic to the Atacama Saltpan, a system historically exposed to environmental changes, and currently subjected to conditions associated with metallic and non-metallic mining and other anthropic activities. Molecular analyses based on nuclear and mitochondrial sequences indicate that the saltpan populations are highly fragmented and that the genetic structure is mainly explained by historical geographic isolation, with little influence of contemporary factors. The microsatellite results suggest a moderate genetic diversity and sharp differentiation mediated by isolation by distance. Additionally, despite the high environmental heterogeneity detected and the marked historical dynamism of the region, our data reveal no signs of demographic instability. The patterns of contemporary gene flow suggest a change in the current genetic structure, based on the geographic proximity and specific environmental conditions for each population. Our results, highlight the role of fragmentation as a modulator of genetic diversity, but also suggest that the historical persistence of isolated populations in naturally dynamic environments could explain the apparent demographic stability detected.
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    Distribution, conservation assessment and management perspectives of Chilean micro-snails of the family Charopidae
    (2023) Collado, Gonzalo A.; Flores, Nataly; Vidal, Marcela A.; Torres-Diaz, Cristian; Valladares, Moises A.
    The biodiversity of molluscs is highly threatened in marine, terrestrial and freshwater ecosystems worldwide. This research aimed at studying the distribution and conservation status of eight poorly-known micro-snails of the genera Stephacharopa and Stephadiscus in Chile. We performed a comprehensive review of literature and databases to determine the occurrences of the species, which were mapped on vector layers containing protected areas and human development infrastructure to find potential threats. Conservation status assessment was performed following the criteria and tools implemented by the International Union for the Conservation of Nature (IUCN) Red List and NatureServe. We also conducted species distribution models, based on maximum entropy, to identify areas that should be prioritised for conservation. Two species meet the criteria for IUCN listing as Critically Endangered (CR), four Endangered (EN), one Vulnerable (Vu) and one Least Concern (LC). This classification is rather coincident with equivalent categories obtained under the NatureServe standard, in which two species were ranked as Critically Imperiled (N1), five Imperiled (N2) and one Vulnerable (N3). We found that Stephacharopa paposensis is the most at-risk species, with only one occurrence not included in a protected area, followed by Stephadiscus stuardoi, with two occurrences, one of them within a protected area. Stephadiscus lyratus was the species with the greatest geographic range, accounting for 17 occurrences, seven matching a protected area. We found wider potential ranges in modelled species that may be useful for prioritising conservation measures. Considering distributional data, protected areas and more than 20 plausible threats identified, we propose potential in situ and ex situ conservation actions to protect these neglected micro-snails.
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    Genomes of the Orestias pupfish from the Andean Altiplano shed light on their evolutionary history and phylogenetic relationships within Cyprinodontiformes
    (2024) Morales, Pamela; Gajardo, Felipe; Valdivieso, Camilo; Valladares, Moises A.; Di Genova, Alex; Orellana, Ariel; Gutierrez, Rodrigo A.; Gonzalez, Mauricio; Montecino, Martin; Maass, Alejandro; Mendez, Marco A.; Allende, Miguel L.
    Background To unravel the evolutionary history of a complex group, a comprehensive reconstruction of its phylogenetic relationships is crucial. This requires meticulous taxon sampling and careful consideration of multiple characters to ensure a complete and accurate reconstruction. The phylogenetic position of the Orestias genus has been estimated partly on unavailable or incomplete information. As a consequence, it was assigned to the family Cyprindontidae, relating this Andean fish to other geographically distant genera distributed in the Mediterranean, Middle East and North and Central America. In this study, using complete genome sequencing, we aim to clarify the phylogenetic position of Orestias within the Cyprinodontiformes order.