Señales genómicas de selección impulsados por el clima en los ecotipos de Colobanthus quitensis (Caryophyllaceae).
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Date
2026
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Publisher
Universidad de Concepción
Abstract
Colobanthus quitensis es una de las dos únicas especies de plantas vasculares que se encuentran en las islas antárticas. Se caracteriza por tener dos ecotipos fisiológicos que se han adaptado a condiciones climáticas diferentes: el ecotipo andino, mejor adaptado a la combinación de altas temperaturas y radiación solar, y el ecotipo antártico, adaptado a temperaturas estivales constantemente bajas. En este estudio, investigamos los patrones de divergencia genómica en C. quitensis a lo largo de su amplio gradiente latitudinal y climático, y evaluamos como la adaptación local a condiciones ambientales contrastantes ha contribuido a la divergencia eco-evolutiva de las poblaciones. Hipotetizamos que son las variables de temperatura y radiación solar las que han impulsado la diferenciación de las poblaciones de C. quitensis, y, en consecuencia, hay SNPs que tienen asociaciones significativas con estas variables. Se muestrearon 14 sitios a lo largo del área de distribución de C. quitensis y se utilizó el método DArtSeq para identificar 31.127 SNPs en 171 individuos. Los análisis de estructura determinaron diez grupos genéticos latitudinales delineados por análisis TESS3. Se utilizaron dos análisis de asociación genoma-ambiente (GEA) para la detección de adaptación al clima: el Modelo Mixto de Factores Latentes (LFMM) y Análisis de Redundancia (RDA), con 6 variables bioclimáticas independientes. El análisis LFMM arrojó 5.928 SNPs candidatos a selección. Complementariamente, el análisis RDA determinó 1.797 SNPs candidatos. De ambas metodologías, se obtuvo un concatenado de 335 SNPs candidatos, donde la BIO9, BIO10 y rsds_max contribuyeron un 89.8% del total. Se detectó según el índice de fijación (FST), que existe una mayor divergencia genética adaptativa y, además, mediante un análisis de varianza molecular (AMOVA), se determinó que las diferencias entre las poblaciones son mayormente explicadas por datos adaptativos que en comparación con los datos neutrales. Finalmente, la matriz neutral exhibió aislamiento por distancia (IBD), mientras que la adaptativa presentó un marcado aislamiento por el ambiente (IBE). Este patrón confirma nuestra hipótesis de que las poblaciones de C. quitensis están en proceso de divergencia ecotípica por selección climática.
Colobanthus quitensis is one of only two vascular plant species occurring on the Antarctic islands. It is characterized by having two physiological ecotypes that have adapted to different climatic conditions: the Andean ecotype, better adapted to the combination of high temperatures and solar radiation, and the Antarctic ecotype, adapted to constantly low summer temperatures. In this study, we investigated the patterns of genomic divergence in C. quitensis along its broad latitudinal and climatic gradient and evaluated how local adaptation to contrasting environmental conditions has contributed to the eco-evolutionary divergence of populations. We hypothesized that temperature and solar radiation variables have driven the differentiation of C. quitensis populations, and consequently, that there are SNPs showing significant associations with these variables. Fourteen sites were sampled across the distribution range of C. quitensis, and the DArTseq method was used to identify 31,127 SNPs in 171 individuals. Structure analyses delineated ten latitudinal genetic groups through TESS3. Two genome-environment associations (GEA) analyses were used for the detection of climate adaptation: the Latent Factor Mixed Model (LFMM) and Redundancy Analysis (RDA), with six independent bioclimatic variables. The LFMM analysis yielded 5,928 candidate SNPs under selection. Complementarily, the RDA analysis identified 1,797 candidate SNPs. From both methodologies, a concatenated set of 335 candidate SNPs was obtained, where BIO9, BIO10, and rsds_max contributed 89.8% of the total. Using the fixation index (FST), greater adaptive genetic divergence was detected; furthermore, through a molecular analysis of variance (AMOVA), it was determined that differences among populations are explained to a greater extent by adaptive data than by neutral data. Finally, through a Pearson correlation analysis, it was elucidated that the neutral matrix exhibits a pattern of isolation by distance (IBD), whereas the candidate SNP matrix exhibits a pattern of isolation by environment (IBE). The marked IBE pattern in the adaptive matrix suggests that, as hypothesized, C. quitensis populations are undergoing a process of ecotypic divergence driven by climate, promoting the local adaptation of its populations.
Colobanthus quitensis is one of only two vascular plant species occurring on the Antarctic islands. It is characterized by having two physiological ecotypes that have adapted to different climatic conditions: the Andean ecotype, better adapted to the combination of high temperatures and solar radiation, and the Antarctic ecotype, adapted to constantly low summer temperatures. In this study, we investigated the patterns of genomic divergence in C. quitensis along its broad latitudinal and climatic gradient and evaluated how local adaptation to contrasting environmental conditions has contributed to the eco-evolutionary divergence of populations. We hypothesized that temperature and solar radiation variables have driven the differentiation of C. quitensis populations, and consequently, that there are SNPs showing significant associations with these variables. Fourteen sites were sampled across the distribution range of C. quitensis, and the DArTseq method was used to identify 31,127 SNPs in 171 individuals. Structure analyses delineated ten latitudinal genetic groups through TESS3. Two genome-environment associations (GEA) analyses were used for the detection of climate adaptation: the Latent Factor Mixed Model (LFMM) and Redundancy Analysis (RDA), with six independent bioclimatic variables. The LFMM analysis yielded 5,928 candidate SNPs under selection. Complementarily, the RDA analysis identified 1,797 candidate SNPs. From both methodologies, a concatenated set of 335 candidate SNPs was obtained, where BIO9, BIO10, and rsds_max contributed 89.8% of the total. Using the fixation index (FST), greater adaptive genetic divergence was detected; furthermore, through a molecular analysis of variance (AMOVA), it was determined that differences among populations are explained to a greater extent by adaptive data than by neutral data. Finally, through a Pearson correlation analysis, it was elucidated that the neutral matrix exhibits a pattern of isolation by distance (IBD), whereas the candidate SNP matrix exhibits a pattern of isolation by environment (IBE). The marked IBE pattern in the adaptive matrix suggests that, as hypothesized, C. quitensis populations are undergoing a process of ecotypic divergence driven by climate, promoting the local adaptation of its populations.
Description
Tesis presentada para optar al grado de Magíster en Ciencias con mención en Botánica.
Keywords
Plantas en peligro, Fisiología vegetal, Diversidad de las plantas, Clima Influencia