Estructura y flujo genético en poblaciones de Deschampsia antarctica É. Desv. en el gradiente austral-antártico.
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Date
2026
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
La Antártica marítima es un sistema de islas y continente geográficamente aislado y con condiciones climáticas extremas que afectan la ecología, evolución y biogeografía de las plantas vasculares que la habitan. Factores climáticos, como las bajas temperaturas en la estación de crecimiento, y los vientos a alta velocidad, podrían incidir en la dinámica de dispersión entre las islas Shetland del sur en Deschampsia antarctica É. Desv., una de las dos especies de plantas vasculares nativas de la Antártica. Por lo que se propone como hipótesis que esta especie presenta un bajo flujo génico entre poblaciones que se verá directamente reflejado en una estructura genética marcada, y por consiguiente una mayor diferenciación entre las poblaciones más distantes entre sí dentro de un gradiente espacial. Este trabajo tiene por objetivo analizar la estructura y flujo génico de poblaciones de D. antarctica en las islas antárticas para buscar diferencias entre y dentro de las poblaciones. Para esto se realizaron extracciones de ADN para 94 individuos provenientes de Isla Navarino (Patagonia), Islas Georgias del sur (Atlántico), e islas antárticas (Coronación, Robert, Rey Jorge, Livingston, Península Byers, Cuverville, Cormoran, Biscoe y Lagotellerie). Posteriormente realizó una aproximación multiloci utilizando Dartseq, secuenciación basada en la reducción de la complejidad del genoma mediante enzimas de restricción y la secuenciación de lecturas cortas para identificar polimorfismos de un solo nucleótido (SNP) en múltiples individuos. Usando como base de datos la matriz imputada de SNP’s se realizaron análisis de varianza molecular AMOVA, para conocer si la mayor variación se daba entre poblaciones o dentro de ellas, seguido de análisis de estructura genética TESS3 y DAPC para distinguir clusters de individuos genéticamente relacionados, distancia genética mediante FST para su aplicación en el análisis de correlación entre distancia genética y distancia ambiental mediante test de Mantel parcial, usando la distancia geográfica como covariable. Esto principalmente con el objetivo de contrastar la hipótesis de aislamiento por distancia (IBD) con la hipótesis de aislamiento por ambiente (IBE). Finalmente, los resultados apuntan a una estructura genética marcada, que delimita las poblaciones, presentando un flujo genético histórico limitado, influido por el ambiente en conjunto con la distancia geográfica sobre la diferenciación de las poblaciones, reflejado por una alta correlación entre la distancia ambiental y la distancia geográfica.
Maritime Antarctica is a geographically isolated system of islands and a continent characterized by extreme climatic conditions that affect the ecology, evolution, and biogeography of the vascular plants that inhabit it. Climatic factors, such as low temperatures during the growing season and high-speed winds, could influence the dispersal dynamics of Deschampsia antarctica É. Desv. among the South Shetland Islands, one of the two species of vascular plants native to Antarctica. Therefore, the hypothesis is proposed that this species exhibits low gene flow between populations, which will be directly reflected in a distinct genetic structure and, consequently, greater differentiation among populations that are more distant from one another within a spatial gradient. The objective of this study is to analyze the genetic structure and gene flow of D. antarctica populations on the Antarctic islands to identify differences between and within populations. To this end, DNA was extracted from 94 individuals from Navarino Island (Patagonia), the South Georgia Islands (Atlantic), and the Antarctic Islands (Coronación, Robert, King George, Livingston, Byers Peninsula, Cuverville, Cormoran, Biscoe, and Lagotellerie). Subsequently, a multilocus analysis was performed using Dartseq, a sequencing method based on reducing genome complexity through restriction enzymes and sequencing short reads to identify single-nucleotide polymorphisms (SNPs) in multiple individuals. Using the imputed SNP matrix as a database, molecular analysis of variance (AMOVA) was conducted to determine whether the greatest variation occurred between populations or within them, followed by TESS3 and DAPC genetic structure analyses to distinguish clusters of genetically related individuals, and genetic distance calculated using for application in the analysis of the correlation between genetic distance and environmental distance via a partial Mantel test, using geographic distance as a covariate. This was primarily done to test the hypothesis of isolation by distance (IBD) against the hypothesis of isolation by environment (IBE). Finally, the results point to a distinct genetic structure that delineates the populations, showing limited historical gene flow, with the environment—in conjunction with geographic distance—influencing population differentiation, as reflected by a high correlation between environmental distance and geographic distance.
Maritime Antarctica is a geographically isolated system of islands and a continent characterized by extreme climatic conditions that affect the ecology, evolution, and biogeography of the vascular plants that inhabit it. Climatic factors, such as low temperatures during the growing season and high-speed winds, could influence the dispersal dynamics of Deschampsia antarctica É. Desv. among the South Shetland Islands, one of the two species of vascular plants native to Antarctica. Therefore, the hypothesis is proposed that this species exhibits low gene flow between populations, which will be directly reflected in a distinct genetic structure and, consequently, greater differentiation among populations that are more distant from one another within a spatial gradient. The objective of this study is to analyze the genetic structure and gene flow of D. antarctica populations on the Antarctic islands to identify differences between and within populations. To this end, DNA was extracted from 94 individuals from Navarino Island (Patagonia), the South Georgia Islands (Atlantic), and the Antarctic Islands (Coronación, Robert, King George, Livingston, Byers Peninsula, Cuverville, Cormoran, Biscoe, and Lagotellerie). Subsequently, a multilocus analysis was performed using Dartseq, a sequencing method based on reducing genome complexity through restriction enzymes and sequencing short reads to identify single-nucleotide polymorphisms (SNPs) in multiple individuals. Using the imputed SNP matrix as a database, molecular analysis of variance (AMOVA) was conducted to determine whether the greatest variation occurred between populations or within them, followed by TESS3 and DAPC genetic structure analyses to distinguish clusters of genetically related individuals, and genetic distance calculated using for application in the analysis of the correlation between genetic distance and environmental distance via a partial Mantel test, using geographic distance as a covariate. This was primarily done to test the hypothesis of isolation by distance (IBD) against the hypothesis of isolation by environment (IBE). Finally, the results point to a distinct genetic structure that delineates the populations, showing limited historical gene flow, with the environment—in conjunction with geographic distance—influencing population differentiation, as reflected by a high correlation between environmental distance and geographic distance.
Description
Tesis presentada para optar al título de Bióloga.
Keywords
Deschampsia Fisiología, Genética, Biogeografía