Browsing by Author "Vianna J.A."
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- ItemExceptional foraging plasticity in King Penguins (Aptenodytes patagonicus) from a recently established breeding site in Tierra del Fuego, Chile(Elsevier B.V., 2021) Pütz K.; Gherardi-Fuentes C.; Simeone A.; García-Borboroglu P.; Godoy C.; García-Borboroglu P.; Godoy C.; Flagg M.; Pedrana J.; Vianna J.A.; Lüthi B.© 2021 The AuthorsAnimals constantly test the borders of their own ecological niche and tend to expand their range, which is now additionally challenged by global climate change. Following human exploitation throughout the Southern Ocean in the 19th and the beginning of the 20th century, numbers of King Penguin breeding pairs have increased and former breeding sites have been re-colonized. Since 2010 a breeding colony became (re-)established at Bahía Inútil, Strait of Magellan, Tierra del Fuego, Chile. The aims of this study were to study the foraging ecology of King Penguins at this new breeding site, which is characterized by a set of different environmental variables as it is located within the confined environment of the Magellan Strait, more than 300 km from the open ocean. During the course of this study, thirty-two birds were successfully equipped with external devices that recorded 206 foraging trips by breeding and non-breeding birds. With one exception, all birds foraged throughout the year exclusively in the Magellan Strait with the main foraging areas located within 100 km from the colony. The diving activities of 15 King Penguins were recorded during 59 foraging trips, the deepest dive was 160 m and the longest dive lasted 6.75 mins. Based on a representative subsample of 3000 dives, mean dive depth was 32 ± 34 m and mean dive duration 117 ± 84 s. Accordingly, foraging trip durations throughout the year were significantly shorter than those recorded for conspecifics elsewhere. In accordance with these changes in foraging behavior, stomach contents from seven birds showed a mix of fish and squid, with Falkland sprats Sprattus fuegensis as the main prey item present in all samples. The implications of these behavioral adaptations are discussed with regard to this unusual confined foraging environment and predicted changes in the performance of King Penguins breeding elsewhere following global change.
- ItemGreen, yellow or black? Genetic differentiation and adaptation signatures in a highly migratory marine turtle(Royal Society Publishing, 2021) Álvarez-Varas R.; Rojas-Hernández N.; Véliz D.; Álvarez-Varas R.; Véliz D.; Álvarez-Varas R.; Heidemeyer M.; Riginos C.; Benítez H.A.; Araya-Donoso R.; Reséndiz E.; Lara-Uc M.; Godoy D.A.; Muñoz-Pérez J.P.; Alarcón-Ruales D.E.; Muñoz-Pérez J.P.; Alfaro-Shigueto J.; Ortiz-Alvarez C.; Mangel J.C.; Alfaro-Shigueto J.; Vianna J.A.© 2021 The Author(s).Marine species may exhibit genetic structure accompanied by phenotypic differentiation related to adaptation despite their high mobility. Two shape-based morphotypes have been identified for the green turtle (Chelonia mydas) in the Pacific Ocean: the south-central/western or yellow turtle and north-central/eastern or black turtle. The genetic differentiation between these morphotypes and the adaptation of the black turtle to environmentally contrasting conditions of the eastern Pacific region has remained a mystery for decades. Here we addressed both questions using a reduced-representation genome approach (Dartseq; 9473 neutral SNPs) and identifying candidate outlier loci (67 outlier SNPs) of biological relevance between shape-based morphotypes from eight Pacific foraging grounds (n = 158). Our results support genetic divergence between morphotypes, probably arising from strong natal homing behaviour. Genes and enriched biological functions linked to thermoregulation, hypoxia, melanism, morphogenesis, osmoregulation, diet and reproduction were found to be outliers for differentiation, providing evidence for adaptation of C. mydas to the eastern Pacific region and suggesting independent evolutionary trajectories of the shape-based morphotypes. Our findings support the evolutionary distinctness of the enigmatic black turtle and contribute to the adaptive research and conservation genomics of a long-lived and highly mobile vertebrate.
- ItemInferring the impact of past climate changes and hunting on the South American sea lion(John Wiley and Sons Inc, 2021) Weinberger C.S.; Faugeron S.; Marquet P.A.; Vianna J.A.; Vianna J.A.; Marquet P.A.; Faugeron S.; Marquet P.A.© 2021 The Authors. Diversity and Distributions published by John Wiley & Sons Ltd.Aim: Many pinniped species have experienced drastic demographic changes due to their interaction with humans. Most studies, however, have failed to detect recent bottlenecks in otariids from genetic data. The South American Sea Lion Otaria flavescens have a long history of population changes associated with interglacial expansion and hunting to almost extinction. This study aimed at investigating these different demographic fluctuations integrating population genetics and phylogeographic approaches. Location: Pacific coast of South America. Methods: Eighty-five samples from the Chilean coast were collected. Eight microsatellite loci were genotyped, and D-Loop mitochondrial DNA (mtDNA) sequenced. Genetic diversity was assessed, and tests of recent genetic bottlenecks were performed. Past demographic changes were inferred based on neutrality tests, adjustment of a sudden expansion model and Bayesian skyline plots. The magnitude and timing of the different population size changes were further investigated through approximate Bayesian computation (ABC) of coalescent inferences. Results: The mtDNA shows relatively high diversity (h = 0.98 and π = 0.01) compared to most otariids, corroborates the divergence between Pacific and Atlantic populations, around 80,000 years ago (ya), and revealed a secondary contact zone in the Magellan strait. Microsatellite data support a second genetic discontinuity at 40°S, associated with post-glacial colonization of Patagonia. ABC analyses confirmed that glaciation affected the effective population size (Ne) all along the Pacific Coast, between ~50,000 and 15,000 ya. A strong reduction of Ne was also inferred for the hunting period (73–66 ya from sampling). Main conclusions: O. flavescens shows clear signatures of susceptibility to climatic and anthropogenic disturbances and a spatial genetic structure that should be taken into account in the context of management and conservation policies. Yet, despite a recent history of demographic bottlenecks, the genetic diversity remains high, likely a consequence of the demographic dynamics in otariids, characterized by large and connected metapopulations.
- ItemOrigins and evolution of extreme life span in pacific ocean rockfishes(American Association for the Advancement of Science, 2021) Kolora S.R.R.; Owens G.L.; Vazquez J.M.; Stubbs A.; Chatla K.; Bachtrog D.; Sudmant P.H.; Owens G.L.; Jainese C.; Seeto K.; McCrea M.; Love M.; Sandel M.W.; Vianna J.A.; Maslenikov K.; Orr J.W.; Sudmant P.H.© 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government WorksPacific Ocean rockfishes (genus Sebastes) exhibit extreme variation in life span, with some species being among the most long-lived extant vertebrates. We de novo assembled the genomes of 88 rockfish species and from these identified repeated signatures of positive selection in DNA repair pathways in long-lived taxa and 137 longevity-associated genes with direct effects on life span through insulin signaling and with pleiotropic effects through size and environmental adaptations. A genome-wide screen of structural variation reveals copy number expansions in the immune modulatory butyrophilin gene family in long-lived species. The evolution of different rockfish life histories is coupled to genetic diversity and reshapes the mutational spectrum driving segregating CpG→TpG variants in long-lived species. These analyses highlight the genetic innovations that underlie life history trait adaptations and, in turn, how they shape genomic diversity.
- ItemSpecialist versus generalist parasites: the interactions between host diversity, environment and geographic barriers in avian malaria(Elsevier Ltd, 2021) Doussang D.; González-Acuña D.; Doussang D.; Sallaberry-Pincheira N.; Cabanne G.S.; Lijtmaer D.A.; Vianna J.A.© 2021 Australian Society for ParasitologyThe specialist versus generalist strategies of hemoparasites in relation to their avian host, as well as environmental factors, can influence their prevalence, diversity and distribution. In this paper we investigated the influence of avian host species, as well as the environmental and geographical factors, on the strategies of Haemoproteus and Plasmodium hemoparasites. We determined prevalence and diversity by targeting their cytochrome b (Cytb) in a total of 2,590 passerine samples from 138 localities of Central and South America, and analysed biogeographic patterns and host-parasite relationships. We found a total prevalence of 23.2%. Haemoproteus presented a higher prevalence (15.3%) than Plasmodium (4.3%), as well as a higher diversity and host specificity. We determined that Plasmodium and Haemoproteus prevalences correlated positively with host diversity (Shannon index) and were significantly influenced by bird diversity, demonstrating a possible “amplification effect”. We found an effect of locality and the avian family for prevalences of Haemoproteus and Plasmodium. These results suggest that Haemoproteus is more specialist than Plasmodium and could be mostly influenced by its avian host and the Andes Mountains.
- ItemSurviving despite reduce MHC variation: selection patterns and genetic variation of the endangered Huillín (Lontra provocax)(Springer Science and Business Media Deutschland GmbH, 2021) Pizarro E.; Mora M.; Vianna J.A.; Medina-Vogel G.© 2021, Mammal Research Institute, Polish Academy of Sciences, Bialowieza, Poland.The major histocompatibility complex (MHC) is a highly polymorphic gene group that mediates the vertebrate immune response through antigen recognition and presentation. The ability to face an emerging infectious disease is greatly attributable to the genetic diversity of the MHC genes due to its main role in the adaptive immune response of vertebrates. The Huillín (Lontra provocax) is an endangered otter from southern Chile whose populations have been threatened due to illegal fur trade and displaced as a result of land use change in southern Chile, facilitating contact with domestic animals and allowing the transmission of infectious diseases. In this study, MHC loci from wild populations of L. provocax were assessed for the first time. Variation and signature of selection were estimated for MHC class I exons 2 and 3, and MHC class II DRB exon 2. Low genetic diversity was found for MHC whereas signatures of historical positive selection are suggested but inconclusive. The recent population bottleneck that occurred in L. provocax due to anthropogenic pressures might have unchained a strong genetic drift that overcomes the effects of positive selection in the MHC loci, diminishing genetic diversity and erasing signatures of selection. These results suggest that L. provocax has a low adaptive capacity and, therefore a great susceptibility to the spread of diseases from domestic and invasive animals towards the endangered L. provocax. This should be considered as a warning about the vulnerability of the species to face emerging infectious diseases.
- ItemTaxonomy based on limited genomic markers may underestimate species diversity of rockhopper penguins and threaten their conservation(John Wiley and Sons Inc, 2021) Frugone M.J.; Poulin E.; Frugone M.J.; Poulin E.; Frugone M.J.; Cole T.L.; Waters J.M.; Cole T.L.; Lopez M.E.; Clucas G.; Clucas G.; Matos-Maravi P.; Lois N.A.; Lois N.A.; Pistorius P.; Bonadonna F.; Trathan P.; Polanowski A.; Wienecke B.; Raya-Rey A.; Raya-Rey A.; Raya-Rey A.; Putz K.; Steinfurth A.; Steinfurth A.; Bi K.; Wang-Claypool C.Y.; Bowie R.C.K.; Vianna J.A.© 2021 The Authors. Diversity and Distributions published by John Wiley & Sons Ltd.Aim: Delimiting recently diverged species is challenging. During speciation, genetic differentiation may be distributed unevenly across the genome, as different genomic regions can be subject to different selective pressures and evolutionary histories. Reliance on limited numbers of genetic markers that may be underpowered can make species delimitation even more challenging, potentially resulting in taxonomic inconsistencies. Rockhopper penguins of the genus Eudyptes comprise three broadly recognized taxa: northern (E. moseleyi), southern (E. chrysocome) and eastern rockhopper (E. filholi). Their taxonomic status has been controversial for decades, with researchers disagreeing about whether E. chrysocome and E. filholi are distinct species or conspecific. Our goal is to evaluate genome-wide patterns of divergence to evaluate genetic differentiation and species delimitation in rockhopper penguins, and to assess which mechanisms may underlie previous discordance among nuclear versus mitochondrial analyses. Location: Sub-Antarctic and temperate coastal regions of the Southern Hemisphere. Methods: We generated reduced-representation genomic libraries using double digest restriction-site associated DNA (ddRAD) sequencing to evaluate genetic differentiation, contemporary migration rates and admixture among colonies of rockhopper penguins. Results: The extent of genetic differentiation among the three taxa was consistently higher than population-level genetic differentiation found within these and other penguin species. There was no evidence of admixture among the three taxa, suggesting the absence of ongoing gene flow among them. Species delimitation analyses based on molecular data, along with other lines of evidence, provide strong support for the taxonomic distinction of three species of rockhopper penguins. Main conclusions: Our results provide strong support for the existence of three distinct species of rockhopper penguins. The recognition of this taxonomic diversity is crucial for the management and conservation of this widely distributed species group. This study illustrates that widespread dispersive seabird lineages lacking obvious morphological differences may nevertheless have complex evolutionary histories and comprise cryptic species diversity.
- ItemThe spatial and trophic ecology of culpeo foxes (Lycalopex culpaeus) in the high Andes of northern Chile(Taylor and Francis Ltd., 2021) Lagos N.; Villalobos R.; Villalobos R.; Vianna J.A.; Espinosa-Miranda C.; Rau J.R.; Iriarte A.© 2021 Informa UK Limited, trading as Taylor & Francis Group.The spatial and trophic ecology of the culpeo fox (Lycalopex culpaeus) was studied in the Salar de Punta Negra basin and the Llullaillaco National Park, in the high Andes of the Region of Antofagasta in northern Chile. The objectives of this study were to understand the feeding ecology, habitat use, and home range and activity pattern of culpeo fox. The study was conducted in an area of approximately 2800 km2 inside the Punta Negra salt flat basin, Llullaillaco NP, the surrounding mountains, and within areas of mining operations. We used methodologies including camera trapping, live trapping and satellite monitoring of L. culpaeus individuals, and diet analysis. Fifteen captures and five recaptures of culpeos were made, and three of them were equipped with satellite tracking collars. The home ranges estimated using the Minimum Convex Polygon (MPC 95%) were: 1029 km2 (female), 809 km2 (female) and 215 km2 (male). Culpeo foxes were nocturnal animals. A larger sample of 282 fecal scats was collected, with the main trophic prey in culpeo fox diet by frequency of occurrence being rodents (74.3%), arthropods (48%), camelids carrion (43.6%), birds (16.3%), vegetation (13.8%) and reptiles (2.5%). Niche breadth was low (0.367).