Browsing by Author "Simeone, Alejandro"

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    Comparative Genomics Supports Ecologically Induced Selection as a Putative Driver of Banded Penguin Diversification
    (2024) Leon, Fabiola; Pizarro, Eduardo; Noll, Daly; Pertierra, Luis R.; Parker, Patricia; Espinaze, Marcela P. A.; Luna-Jorquera, Guillermo; Simeone, Alejandro; Frere, Esteban; Dantas, Gisele P. M.; Cristofari, Robin; Cornejo, Omar E.; Bowie, Rauri C. K.; Vianna, Juliana A.
    The relative importance of genetic drift and local adaptation in facilitating speciation remains unclear. This is particularly true for seabirds, which can disperse over large geographic distances, providing opportunities for intermittent gene flow among distant colonies that span the temperature and salinity gradients of the oceans. Here, we delve into the genomic basis of adaptation and speciation of banded penguins, Gal & aacute;pagos (Spheniscus mendiculus), Humboldt (Spheniscus humboldti), Magellanic (Spheniscus magellanicus), and African penguins (Spheniscus demersus), by analyzing 114 genomes from the main 16 breeding colonies. We aim to identify the molecular mechanism and genomic adaptive traits that have facilitated their diversifications. Through positive selection and gene family expansion analyses, we identified candidate genes that may be related to reproductive isolation processes mediated by ecological thermal niche divergence. We recover signals of positive selection on key loci associated with spermatogenesis, especially during the recent peripatric divergence of the Gal & aacute;pagos penguin from the Humboldt penguin. High temperatures in tropical habitats may have favored selection on loci associated with spermatogenesis to maintain sperm viability, leading to reproductive isolation among young species. Our results suggest that genome-wide selection on loci associated with molecular pathways that underpin thermoregulation, osmoregulation, hypoxia, and social behavior appears to have been crucial in local adaptation of banded penguins. Overall, these results contribute to our understanding of how the complexity of biotic, but especially abiotic, factors, along with the high dispersal capabilities of these marine species, may promote both neutral and adaptive lineage divergence even in the presence of gene flow.
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    Entanglement and Drowning of a Magellanic Penguin (Spheniscus magellanicus) in a Gill Net Recorded by a Time-Depth Recorder in South-Central Chile
    (2011) Puetz, Klemens; Hiriart-Bertrand, Luciano; Simeone, Alejandro; Riquelme, Victoria; Reyes-Arriagada, Ronnie; Luethi, Benno
    Various mitigation measures have been implemented to reduce incidental seabird mortality in longline and trawl fisheries but little attention has been given to artisanal fishing. In the 2008/09 breeding season, during a study of foraging of Humboldt, Spheniscus humboldti, and Magellanic Penguins, S. magellanicus, breeding on Punihuil islets, southern Chile, a Magellanic Penguin equipped with a time-depth recorder became entangled and subsequently drowned in a gill net set for Corvina Drum (Cilia gilberti). The device was returned by fishermen and the data appear to be the first documented case of such a drowning in a marine, air-breathing vertebrate. According to the data, while diving to a depth of more than 50 in, the bird became entangled and drowned, remaining below 60 m for nearly 21 hours until the net was hauled. Although only a single incident is reported, there are indications that incidental mortality of penguins, other seabirds and marine mammals is more common in artisanal fisheries than previously anticipated. Received 20 April 2010, accepted 5 July 2010.
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    Molecular Epidemiology of Avian Malaria in Wild Breeding Colonies of Humboldt and Magellanic Penguins in South America
    (2015) Sallaberry Pincheira, Nicole; Gonzalez Acuña, Daniel; Herrera Tello, Yeritza Romainne; Dantas, Gisele P. M.; Luna Jorquera, Guillermo; Frere, Esteban; Valdés Velásquez, Armando; Simeone, Alejandro; De Abreu, Vianna Juliana
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    Uncovering population structure in the Humboldt penguin (Spheniscus humboldti) along the Pacific coast at South America
    (2019) Dantas, Gisele P. M.; Oliveira, Larissa R.; Santos, Amanda M.; Flores, Mariana D.; de Melo, Daniella R.; Simeone, Alejandro; Gonzalez-Acuna, Daniel; Luna-Jorquera, Guillermo; Le Bohec, Celine; Valdes-Velasquez, Armando; Cardena, Marco; Morgante, Joao S.; Vianna, Juliana A.
    The upwelling hypothesis has been proposed to explain reduced or lack of population structure in seabird species specialized in food resources available at cold-water upwellings. However, population genetic structure may be challenging to detect in species with large population sizes, since variation in allele frequencies are more robust under genetic drift. High gene flow among populations, that can be constant or pulses of migration in a short period, may also decrease power of algorithms to detect genetic structure. Penguin species usually have large population sizes, high migratory ability but philopatric behavior, and recent investigations debate the existence of subtle population structure for some species not detected before. Previous study on Humboldt penguins found lack of population genetic structure for colonies of Punta San Juan and from South Chile. Here, we used mtDNA and nuclear markers (10 microsatellites and RAG1 intron) to evaluate population structure for 11 main breeding colonies of Humboldt penguins, covering the whole spatial distribution of this species. Although mtDNA failed to detect population structure, microsatellite loci and nuclear intron detected population structure along its latitudinal distribution. Microsatellite showed significant R-st values between most of pairwise locations (44 of 56 locations, R-st = 0.003 to 0.081) and 86% of individuals were assigned to their sampled colony, suggesting philopatry. STRUCTURE detected three main genetic clusters according to geographical locations: i) Peru; ii) North of Chile; and iii) Central-South of Chile. The Humboldt penguin shows signal population expansion after the Last Glacial Maximum (LGM), suggesting that the genetic structure of the species is a result of population dynamics and foraging colder water upwelling that favor gene flow and phylopatric rate. Our findings thus highlight that variable markers and wide sampling along the species distribution are crucial to better understand genetic population structure in animals with high dispersal ability.