Two Genetically Distinct Lineages in Galician Populations of the Three‐Spined Stickleback ()
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
ABSTRACT The three‐spined stickleback () is a widely used model for studying the genetic basis of phenotypic variation. However, genomic studies have focused primarily on a limited number of geographic regions, leaving some regions underrepresented. In this study, we investigated genetic variation in stickleback populations from Galicia in northwestern Spain, a region near the southern limit of the species' European distribution that has been proposed as a glacial refugium but remains underrepresented in genomic analyses. Using double‐digest RAD sequencing, we identified two genetically distinct lineages within Galician populations. These lineages showed substantial genetic differentiation (mean= 0.435) and also exhibited fine‐scale population structure within each lineage. We detected morphological variation among Galician populations, although its association with lineage identity and ecology remains unclear. Most individuals carried the low‐plated allele at a major armor plate locus (), which is commonly found in freshwater populations throughout the species' range. Using whole‐genome sequencing, we showed that both lineages were assigned to the Southern European Clade of the three‐spined stickleback. Our results reveal previously unrecognized phylogeographic structure within Galician sticklebacks and highlight the importance of sampling underrepresented regions in model systems. These populations provide a useful system for investigating how geographic structure shapes pa
Abstract
ABSTRACT The three‐spined stickleback () is a widely used model for studying the genetic basis of phenotypic variation. However, genomic studies have focused primarily on a limited number of geographic regions, leaving some regions underrepresented. In this study, we investigated genetic variation in stickleback populations from Galicia in northwestern Spain, a region near the southern limit of the species' European distribution that has been proposed as a glacial refugium but remains underrepresented in genomic analyses. Using double‐digest RAD sequencing, we identified two genetically distinct lineages within Galician populations. These lineages showed substantial genetic differentiation (mean= 0.435) and also exhibited fine‐scale population structure within each lineage. We detected morphological variation among Galician populations, although its association with lineage identity and ecology remains unclear. Most individuals carried the low‐plated allele at a major armor plate locus (), which is commonly found in freshwater populations throughout the species' range. Using whole‐genome sequencing, we showed that both lineages were assigned to the Southern European Clade of the three‐spined stickleback. Our results reveal previously unrecognized phylogeographic structure within Galician sticklebacks and highlight the importance of sampling underrepresented regions in model systems. These populations provide a useful system for investigating how geographic structure shapes patterns of genetic and phenotypic variation. Two genetically distinct lineages of three‐spined sticklebacks occur in Galicia, Spain. Both belong to the Southern European Clade of the three‐spined stickleback. graphical