Browsing by Author "Poulin, Elie"

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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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    Antarctic shallow suhtidal echinoderms: is the ecological success of broadcasters related to ice disturbance?
    (SPRINGER, 2007) Palma, Alvaro T.; Poulin, Elie; Silva, Marcelo G.; San Martin, Roberto B.; Munoz, Carlos A.; Diaz, Angie D.
    One characteristic pattern found in the marine Antarctic shallow environments is the unusually high proportion of species with protected and pelagic lecitotrophic development modes. However, species with planktotrophic development generally appear as the most conspicuous types of organisms in these environments. The Antarctic shallow benthos is considered as one of the most disturbed in the world, mainly due to the action of ice, thus one could hypothesize that such an environment should favor organisms with high dispersal capability. In order to test this general hypothesis, for two consecutive summers (2004-2005) and at two locations, we quantified the abundance and size distribution of most echinoderms present along bathymetric transects. Our results show the predominance of broadcasters (i.e., Sterechinus neumayeri and Odontaster validus) at a location where disturbances are common, while brooders (e.g., Abatus agassizii) only occurred at shallower depths of the least disturbed location. These results not only corroborate the hypothesis that local disturbance is an important factor generating these ecological patterns, but also suggest how ice-related disturbances could represent a major selecting agent behind the patterns of species diversity at an evolutionary scale in Antarctica.
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    Chinstrap penguin population genetic structure: one or more populations along the Southern Ocean?
    (2018) Mura-Jornet, Isidora; Pimentel, Carolina; Dantas, Gisele P. M.; Petry, Maria Virginia; Gonzalez-Acuna, Daniel; Barbosa, Andres; Lowther, Andrew D.; Kovacs, Kit M.; Poulin, Elie; Vianna, Juliana
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    Cryptic speciation in gentoo penguins is driven by geographic isolation and regional marine conditions: Unforeseen vulnerabilities to global change
    (2020) Pertierra, Luis R.; Segovia, Nicolás I.; Noll, Daly; Martínez, Pablo A.; Pliscoff, Patricio; Barbosa, Andrés; Vianna, Juliana; Aragón, Pedro; Raya Rey, Andrea; Pistorius, Pierre; Trathan, Phil; Polanowski, Andrea; Bonadonna, Francesco; Le Bohec, Célin; Bi, Ke; Wang-Claypool, Cynthia Y.; González Acuña, Daniel; Dantas, Gisele P. M.; Bowie, Rauri C. K.; Poulin, Elie
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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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    Genetic population structure in the Chilean jack mackerel, Trachurus murphyi (Nichols) across the South-eastern Pacific Ocean
    (2009) Cardenas, Leyla; Silva, Andrea X.; Magoulas, Antonios; Cabezas, Josefina; Poulin, Elie; Patricio Ojeda, F.
    The Chilean jack mackerel Trachurus murphyi, is a pelagic fish from the Carangidae family that is distributed in the South Pacific Ocean. Because this species constitutes an important economic resource across the South Pacific and plays an important ecological role in this ecosystem there is a growing interest in determining its population structure. In this study, we used molecular markets (mitochondrial DNA sequences and microsatellites) from Chilean jack mackerel samples to investigate its genetic population structure across the South Pacific Ocean. The mitochondrial DNA did not detect a genetic structure in T murphyi populations in the Pacific Ocean, but revealed very low haplotype diversity and a short genealogy history compared to other small-pelagic species. The same general pattern of a lack of genetic structure was found with microsatellite loci; however, a large genetic diversity was revealed with microsatellite markers. The present results did not support the existence of different stock units for T murphyi across the South Pacific Ocean but a more holistic approach will be necessary to determine an adequate management strategy for this fishery. (C) 2009 Elsevier B.V. All rights reserved.
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    Genomic Introgression and Adaptation of Southern Seabird Species Facilitate Recent Polar Colonization
    (2025) Jorquera Faundez, Maria Josefina; Morales, Lucina; Ng, Elize Y.X.; Noll, Daly; Pertierra, Luis R.; Pliscoff, Patricio; Balza, Ulises; Boulinier, Thierry; Gamble, Amandine; Kasinsky, Tatiana; McInnes, Julie C.; Marin, Juan Carlos; Olmastroni, Silvia; Pistorius, Pierre; Phillips, Richard A.; Gonzalez-Solis, Jacob; Emmerson, Louise; Poulin, Elie; Bowie, Rauri C.K.; Burridge, Christopher P.; Vianna, Juliana
    Genomic adaptation and introgression can occur during the speciation process, enabling species to diverge in their frequencies of adaptive alleles or acquire new alleles that may promote adaptation to environmental changes. There is limited information on introgression in organisms from extreme environments and their responses to climate change. To address these questions, we focused on the 3 southern skua species, selected for their widespread distribution across the Southern Hemisphere and their complex history of speciation and introgression events. Our genomic data reveal that these skuas underwent diversification around the Penultimate Glacial Period, followed by subsequent demographic expansion. We identified a geographic region of introgression among species that followed a directional pattern sourced from the Antarctic continent, South America, and east to west in subantarctic islands, all converging towards the Antarctic Peninsula. The 3 skua species and admixed individuals exhibited a unique pattern of putative genes under selection, allowing adaptation to extreme conditions. Individuals with a higher proportion of Brown Skua ancestry showed signs of selection on genes related to reproductive isolation, while admixed individuals with a higher proportion of South Polar Skua ancestry displayed patterns resembling those of the South Polar Skua. Introgression may be a key mechanism of adaptation for many species that may help buffer against the ongoing climate change.
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    Have Historical Climate Changes Affected Gentoo Penguin (Pygoscelis papua) Populations in Antarctica?
    (2014) Pena M., Fabiola; Poulin, Elie; Dantas, Gisele P. M.; Gonzalez-Acuna, Daniel; Petry, Maria Virginia; Vianna, Juliana A.
    The West Antarctic Peninsula (WAP) has been suffering an increase in its atmospheric temperature during the last 50 years, mainly associated with global warming. This increment of temperature trend associated with changes in sea-ice dynamics has an impact on organisms, affecting their phenology, physiology and distribution range. For instance, rapid demographic changes in Pygoscelis penguins have been reported over the last 50 years in WAP, resulting in population expansion of sub-Antarctic Gentoo penguin (P. papua) and retreat of Antarctic Adelie penguin (P. adeliae). Current global warming has been mainly associated with human activities; however these climate trends are framed in a historical context of climate changes, particularly during the Pleistocene, characterized by an alternation between glacial and interglacial periods. During the last maximal glacial (LGM similar to 21,000 BP) the ice sheet cover reached its maximum extension on the West Antarctic Peninsula (WAP), causing local extinction of Antarctic taxa, migration to lower latitudes and/or survival in glacial refugia. We studied the HRVI of mtDNA and the nuclear intron beta fibint7 of 150 individuals of the WAP to understand the demographic history and population structure of P. papua. We found high genetic diversity, reduced population genetic structure and a signature of population expansion estimated around 13,000 BP, much before the first paleocolony fossil records (similar to 1,100 BP). Our results suggest that the species may have survived in peri-Antarctic refugia such as South Georgia and North Sandwich islands and recolonized the Antarctic Peninsula and South Shetland Islands after the ice sheet retreat.
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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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    Mitochondrial DNA variation and systematics of the guanaco (Lama guanicoe, Artiodactyla: Camelidae)
    (2008) Marín, Juan C.; Bonacic Salas, Cristián; Palma Vásquez, Ramón Eduardo; Poulin, Elie
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    Octodon degus kin and social structure
    (2016) Davis, Garrett T.; Vasquez, Rodrigo A.; Poulin, Elie; Oda, Esteban; Bazan Leon, Enrique A.; Ebensperger Pesce, Luis Alberto; Hayes, Loren D.
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    Phylogeny and biogeography of Muusoctopus (Cephalopoda: Enteroctopodidae)
    (2016) Ibáñez, Christian M.; Pardo Gandarillas, María Cecilia; Peña, Fabiola; Gleadall, Ian G.; Poulin, Elie; Sellanes, Javier
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    Phylogeographic Structure in Benthic Marine Invertebrates of the Southeast Pacific Coast of Chile with Differing Dispersal Potential
    (2014) Pardo Gandarillas, María Cecilia; Meynard, Andrés.; Faugeron, Sylvain Wielfrid; Poulin, Elie
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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.
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    Sistemática, taxonomía y domesticación de alpacas y llamas: nueva evidencia cromosómica y molecular
    (2007) Marín, Juan C.; Bonacic Salas, Cristián; Palma Vásquez, Ramón Eduardo; Poulin, Elie
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    Spatial patterns of congruence or mismatch between taxonomic, functional, and phylogenetic diversity and endemism of perennial flora along the aridity gradient of Chile
    (2024) Poch, Paola; Poulin, Elie; Perez, Maria Fernanda; Peralta, Gioconda; Hinojosa, Luis Felipe
    Introduction: Understanding the relationships between taxonomic, functional, and phylogenetic diversity and endemism across environmental gradients is essential for elucidating the eco-evolutionary mechanisms that shape local plant communities. Methods: A database was compiled from field surveys, national herbarium records, and virtual records of perennial plant specimens collected in the aridity gradient of northern Chile, between 18 and 32 degrees S. A large-scale dated phylogeny of available perennial plants was used, and 11 functional traits were selected to construct a dendrogram using the Unweighted Pair-Group Method with Arithmetic Mean (UPGMA) method for the species present in our database. We calculated spatial patterns of a-diversity, including taxonomic (TD), functional (FD), and phylogenetic (PD) diversity, as well as weighted (WE), functional (FE), and phylogenetic (PE) endemism. We used multiscale geographically weighted regression (MGWR) to identify spatial congruencies and discrepancies among these dimensions and to test different eco-evolutionary processes. Results: The diversity indices TD, FD and PD showed similar geographic patterns (R2 > 0.93), with lower diversity observed in absolute desert regions. The pattern of weighted endemism (WE) showed a weak association with functional endemism (FE) and phylogenetic endemism (PE) (local R2 < 0.48). The regions with lower FD or PD than expected given the TD (i.e. FDWE and PE>WE), they are found in arid, high Andean and transitional zones, at different altitudes, which would indicate a greater presence of phylogenetic lineages and species with morpho-functional traits related to extreme environmental conditions and transitional biomes (arid-semiarid). Discussion: These spatial discrepancies suggest different eco-evolutionary drivers between the dimensions of diversity and endemism (taxonomic, functional, and phylogenetic). Areas of high diversity and high endemism do not necessarily coincide, and both should be addressed by conservation efforts.
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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.