Browsing by Author "Maturana, Claudia S."

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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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    DNA barcoding of marine polychaetes species of southern Patagonian fjords
    (2011) Maturana, Claudia S.; Moreno, Rodrigo A.; Labra, Fabio A.; Gonzalez-Wevar, Claudio A.; Rozbaczylo, Nicolas; Carrasco, Franklin D.; Poulin, Elie
    Accurate species identification remains a basic first step in any study of biodiversity, particularly for global changes and their consequences. Thus, there is a pressing need for taxonomic expertise in a broad range of taxa. DNA barcoding has proved to be a powerful alternative method to traditional morphological approaches, allowing to complement identification techniques for living organisms. In this study, we assess intraspecific and interspecific genetic divergence among marine polychaetes from Patagonian fjords of southern Chile, using mitochondrial Cytochrome c Oxidase Subunit I (COI) gene. Our results showed that a total of 13 polychaetes species identified in this study exhibited high levels of interspecific variation among 31 analyzed sequences. Mean pairwise sequence distances comparisons based on K2P within species ranged from 0.2 to 0.4%. In contrast, interspecific comparisons were much higher and ranged between 18 to 47%, with the exception of the congeneric species Asychis chilensis and Asychis amphiglypta that showed high levels of genetic similarities and absence of reciprocal monophyly. This study presents the first information on DNA barcoding for polychaetes species in the southern Chile, and it establishes the effectiveness of DNA barcoding for identification of marine polychaetes species from Patagonian Fjords, thus making it available to a much broader range of scientists.
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    Restricted geographic distribution and low genetic diversity of the brooding sea urchin Abatus agassizii (Spatangoidea: Schizasteridae) in the South Shetland Islands: A bridgehead population before the spread to the northern Antarctic Peninsula?
    (2012) Diaz, Angie; Alejandro Gonzalez-Wevar, Claudio; Maturana, Claudia S.; Palma, Alvaro T.; Poulin, Elie; Gerard, Karin
    The glacial cycles of the Pleistocene have promoted the principal climatic changes of the Southern Ocean, and motivated scientific interest regarding the strategies developed by marine benthic invertebrates to tolerate and overcome the extension and contraction of the ice sheet on the Antarctic continental platform. A recent study of the bathymetric zonation and distribution of macro-invertebrates in a shallow subtidal area of Fildes Bay (King George Island, South Shetlands Islands, Antarctica) highlighted the presence of a large aggregation of the brooding sea urchin Abatus agassizii, whose geographic distribution is known only for localities south of the Antarctic convergence (Antarctic Peninsula and South Shetland and South Georgia Islands in the Scotia Arc). Its presence is atypical, given that these shallow populations should have been erased from the vicinity of the Antarctic Peninsula by the advances and retreats of the ice sheet, and the absence of a larval stage associated with brooding should limit re-colonization from northern Subantarctic areas. The aim of the study was to evaluate whether A. agassizii may have survived the glaciations in its narrow bathymetric range in the South Shetland Islands, or whether this population corresponds to a newcomer that re-colonized the area despite its low dispersal capacities. For this, we combined multidisciplinary approaches based on the geographical distribution of A. agassizii, its genetic diversity and its phylogenetic relationships with other species of the genus. In spite of an intensive sampling effort, the low occurrence of A. agassizii indicated that its distribution is very scarce along the Shetlands Islands and the Antarctic Peninsula, and seems to be restricted to protected and ice-free areas of Fildes Bay in King George Island. Moreover, this population presented very low genetic diversity associated with the signal of a recent demographic expansion. Finally, the reconstruction of the phylogenetic relationships among species of Abates using mitochondrial COI sequences established the affinity of the Antarctic A. agassizii with Subantarctic species. Based on these results we consider that the presence of this species in the Shetland Islands more likely corresponds to a recent re-colonization from Antarctic Islands located further north.