Santiago Guillermo Ceballos

• Doctor in Biology
• National University of Tierra del Fuego

Aim To understand the influence of Andean uplifts and glacial cycles on South American biodiversity, we delve into the population genetics and evolutionary history of a unique subantarctic island raptor specialised in exploiting marine food webs. Location Islands in Tierra del Fuego and Malvinas/Falklands. Time period Last glacial period to the p...

Monitoring of endangered raptors is challenging for species that live on remote systems such as islands. Here, we present the insights of an analysis combining various sampling techniques to monitor the endangered Striated Caracara (Phalcoboenus australis) populations in the subantarctic region. We complement traditional banding and monitoring of n...

The fish biodiversity of the Beagle Channel is insufficiently assessed, poorly managed, and threatened by exotic species. Novel, rapid, and cost-effective DNA-based approaches are valuable for understanding fish communities and biomonitoring in remote areas. Here, we evaluate the potential of environmental DNA (eDNA) metabarcoding for assessing fis...

Otaria flavescens has been one of the most heavily exploited pinnipeds during the last 200 years, with depletion of ~90% in some colonies. After the prohibition on sealing in South America, populations stabilized except for the Uruguayan population, which showed a constant decrease. The underlying causes of its decline are unknown. This study used...

Sex identification is a common objective in molecular ecology. While many vertebrates display sexual dimorphism, determining the sex can be challenging in certain situations, such as species lacking clear sex-related phenotypic characteristics or in studies using non-invasive methods. In these cases, DNA analyses serve as valuable tools not only fo...

Hybridization and introgression are recognized as mechanisms promoting genetic variability during evolutionary radiations. We examined the impact of introgression in the process of speciation, focusing on the Antarctic icefish genus Chionodraco. Our analyses confirmed that the three Chionodraco species (Chionodraco hamatus, Chionodraco myersi, and...

Otaria flavescens has been one of the most heavily exploited pinnipeds during the last 200 years with depletions of about 90% in some colonies. After the prohibition on sealing in South America, populations became stabilized except for the Uruguayan population, which showed a constant decrease. The underlying causes of its decline are unknown. This...

Otaria flavescens is one of the most heavily exploited pinnipeds during the last 200 years, with depletions of about 90% in some colonies. After the prohibition on sealing in South America, most populations stabilized at lower levels than in the pre-harvest period, but with an increasing trend over a wide distribution range. An exception is given b...

Otaria flavescens has been one of the most heavily exploited pinnipeds during the last 200 years with depletions of about 90% in some colonies. After the prohibition on sealing in South America, populations became stabilized except for the Uruguayan population, which showed a constant decrease. The underlying causes of its decline have remained unk...

Identifying the population genetic structure and adaptive diversity of fishery resources is essential for their resilience and sustainability. Pleoticus muelleri is one of the most important fishing resources in Argentina. It inhabits the Southwestern Atlantic Ocean from 20° to 50° S. We genotyped 1740 SNPs in 42 individuals using Restriction Site-...

The second wave of COVID-19 occurred in South America in early 2021 and was mainly driven by Gamma and Lambda variants. In this study, we aimed to describe the emergence and local genomic diversity of the SARS-CoV-2 Lambda variant in Argentina, from its initial entry into the country until its detection ceased. Molecular surveillance was conducted...

Assigning sex to individuals without previous information is a common objective of molecular ecology. Here, we developed a framework for sexing animals by using two indexes based on the different properties of the mammalian sexual chromosomes. We mapped RAD-seq loci to a reference genome to obtain missingness and coverage depth from chromosomes Y,...

The COVID-19 pandemic has lately been driven by Omicron. This work aimed to study the dynamics of SARS-CoV-2 Omicron lineages during the third and fourth waves of COVID-19 in Argentina. Molecular surveillance was performed on 3431 samples from Argentina, between EW44/2021 and EW31/2022. Sequencing, phylogenetic and phylodynamic analyses were perfor...

Introduction : Coinfection with two SARS-CoV-2 viruses is still a very understudied phenomenon. Although next generation sequencing methods are very sensitive to detect heterogeneous viral populations in a sample, there is no standardized method for their characterization, so their clinical and epidemiological importance is unknown. Material and m...

Patagonia is an understudied area, especially when it comes to population genomic studies with relevance to fishery management. However, the dynamic and heterogeneous landscape in this area can harbor an important but cryptic genetic population structure. Once such information is revealed, it can be integrated into the management of infrequently in...

Patagonia is an understudied area, especially when it comes to population genomic studies with relevance to fishery management. However, the dynamic and heterogeneous landscape in this area can harbor important but cryptic genetic population structure. Once such information is revealed, it can be integrated into the management of infrequently inves...

Patagonia is an understudied area, especially when it comes to population genomic studies with relevance to fishery management. However, the dynamic and heterogeneous landscape in this area can harbor important but cryptic genetic population structure. Once such information is revealed, it can be integrated into the management of infrequently inves...

The giant Antarctic toothfish Dissostichus mawsoni is one of the most economically valued fishery resources from the Southern Ocean. However, the distinctive biological characteristics and life history of this species, including large body size, long life span, late sexual maturity, and specialization to freezing polar waters, make it particularly...

Background The impressive adaptive radiation of notothenioid fishes in Antarctic waters is generally thought to have been facilitated by an evolutionary key innovation, antifreeze glycoproteins, permitting the rapid evolution of more than 120 species subsequent to the Antarctic glaciation. By way of contrast, the second-most species-rich notothenio...

The genetic relationships between the Pacific and the Atlantic populations of marine coastal biota in Southern South America have been analyzed in few studies, most of them relying on a single mitochondrial locus. We analyzed 10 polymorphic microsatellite loci, isolated from a dinucleotide-enriched Eleginops maclovinus genomic library, in a total o...

Fishes of the perciform suborder Notothenioidei, which dominate the ichthyofauna in the freezing waters surrounding the Antarctic continent, represent one of the prime examples of adaptive radiation in a marine environment. Driven by unique adaptations, such as antifreeze glycoproteins that lower their internal freezing point, notothenioids have no...

During the research programme conducted on the OV Puerto Deseado in the summers of 2011 and 2013, 36 stations were sampled using a demersal net at depths between 53–590m in the Antarctic Peninsula and South Shetland Islands.Atotal 3378 fish specimens belonging to 36 species were recorded. Notothenidae was the best-represented family in species numb...

Seasonal growth of Galaxias maculatus in Tierra del Fuego, at the southern limit of its distribution, can be explained by the variation in extrinsic factors, and experiments with fasting in summer conditions would allow researchers to focus on the potential feeding/fasting conditions independent of other seasonal cues, and thus distinguish the effe...

Phylogeography studies add insights into the geographic and evolutionary processes that underline the genetic divergence of populations. This work examines the geographic genetic structure of the Patagonian blennie, Ele-ginops maclovinus, a notothenioid (Perciformes) endemic to South American temperate and sub-Antarctic waters, using mitochondrial...

Eleginops maclovinus, the Patagonian blennie, is a notothenioid (Perciformes) endemic to South American temperate and sub-Antarctic waters. Here, we report ten polymorphic microsatellite loci isolated from a dinucleotide-enriched E. maclovinus genomic library. Among 48 individuals, the number of alleles per locus ranged from eight to 41, and the ob...

Phylogeography studies add insights into the geographic and evolutionary processes that underline the genetic divergence of populations. This work examines the geographic genetic structure of the Patagonian blennie, Eleginops maclovinus, a notothenioid (Perciformes) endemic to South American temperate and sub-Antarctic waters, using mitochondrial D...

The radiation of notothenioid fishes (Perciformes) in Antarctic waters was likely the result of an absence of competition in the isolated Antarctic waters and key traits such as the production of antifreeze glycoprotein and buoyancy modifications. Although notothenioids lack a swim bladder, the buoyancy of Antarctic species, ranging from neutrally...

Different hypotheses attempt to explain how different stages of organisms with complex life cycles respond to environmental changes. Most studies have focused at the among-species level showing similar responses to temperature throughout ontogeny. However, there is no agreement about the pattern expected at the intraspecific scale where a strong se...

In this paper we provide the first report of the presence of exotic Chinook salmon (Oncorhynchus tshawytscha) in two rivers off the Beagle Channel, Lapataia and Ovando, in southern Tierra del Fuego. We also confirm that successful reproduction occurred in the fall of 2007, as we captured yearlings in freshwater. Scale pattern analyses of adult fish...

The energy density (ED) of nine species of sub-Antarctic fishes was estimated by calorimetry. The fish, seven notothenioids, one atherinopsid and one galaxiid, represents some of the more abundant species in the ichthyofauna of the Beagle Channel. Principal-components analysis (PCA) of the ED of the different organs/tissues indicated that PC(1) and...

The present study first addressed the question of whether developmental time (DT) and viability (VT) vary clinally along latitudinal and altitudinal gradients in Drosophila buzzatii, an autochthonous specialist and the generalist invasive Drosophila melanogaster. Coincident and positive altitudinal clines across species and, direct and inverse lati...

Question: Developmental time and metabolic rate are correlated at higher levels of organization. Does this allometric relationship scale down to the intraspecific level? Methods: We exposed flies of three species of Drosophila collected at contrasting altitudes and similar latitudes to varying experimental thermal regimes. Metabolic rate was measur...