BUSCADOR RECOLECTA

Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/352423

Glacial cycles lead to periodic population interbreeding and isolation in warm-adapted species, which impact genetic structure and evolution. However, the effects of these processes on highly mobile and more cold-tolerant species are not well understood. This study aims to shed light on the phylogeographic history of Aglais urticae, a butterfly species with considerable dispersal ability, and a wide Palearctic distribution reaching the Arctic. Through the analysis of genomic data, four main genetic lineages are identified: European, Sierra Nevada, Sicily/Calabria/Peloponnese, and Eastern. The results indicate that the Sardo-Corsican endemic taxon ichnusa is a distinct species. The split between the relict lineages in southern Europe and the main European lineage is estimated to have happened 400¿450 thousand years ago, with admixture observed during the Quaternary glacial cycles, and still ongoing, albeit to a much smaller extent. These results suggest that these lineages may be better treated as subspecific parapatric taxa. Ecological niche modelling supported the existence of both Mediterranean and extra-Mediterranean refugia during the glacial periods, with the main one located on the Atlantic coast. Nevertheless, gene flow between populations was possible, indicating that both differentiation and admixture have acted continuously across glacial cycles in this cold-tolerant butterfly, generally balancing each other but producing differentiated lineages in the southern peninsulas. We conclude that the population dynamics and the processes shaping the population genetic structure of cold-adapted species during the Quaternary ice ages may be different than those classically accepted for warm-adapted species., This research was supported by grants PID2019-107078GB-I00 and PID2022-139689NB-I00 (funded by Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 and ERDF A way of making Europe) and by grant 2021-SGR-00420 from Departament de Recerca i Universitats de la Generalitat de Catalunya to RV, by grant CGL2014-57784-P funded by MCIN/AEI/10.13039/501100011033 to DG, by PRE2020-094870 funded by MCIN/AEI/10.13039/501100011033 and ‘European Social Fund (ESF) Investing in your future’ to VM, and by BES-2017-080641 funded by MCIN/AEI/10.13039/501100011033 and by ‘ESF Investing in your future’ to JCH. L.D. acknowledges the support of NBFC to University of Florence, Department of Biology, funded by the Italian Ministry of University and Research, PNRR, Missione 4 Componente 2, ‘Dalla ricerca all'impresa’, Investimento 1.4, Project CN00000033 and by several projects with the Direttiva Biodiversità of the Italian Environmental Ministry. G.T. was supported by grant PID2020-117739GA-100 funded by Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 and by grant 2021-SGR-01334 from Departament de Recerca i Universitats de la Generalitat de Catalunya., Abstract 1 INTRODUCTION 2 MATERIALS AND METHODS 2.1 Sampling 2.2 ddRADseq library preparation 2.3 Data processing 2.4 Population genetic structure 2.5 Phylogenetic inference and gene flow analyses 2.6 Genetic diversity analyses 2.7 Demographic history 2.8 Ecological niche modelling (ENM) 2.9 Wolbachia infection analysis 3 RESULTS 3.1 Principal component analysis 3.2 Genetic structuring and hybridization between lineages 3.3 Phylogenetic inference 3.4 Gene flow analyses 3.5 Genetic diversity analyses 3.6 Demographic history 3.7 Ecological niche modelling 3.8 Wolbachia infection analysis 4 DISCUSSION 4.1 Genomic data clarify previous mitochondrial results 4.2 Evidence of admixture 4.3 Genetic diversity 4.4 The opposed forces of differentiation by isolation and admixture by gene flow 4.5 A complex scenario of differentiation with gene flow AUTHOR CONTRIBUTIONS ACKNOWLEDGEMENTS CONFLICT OF INTEREST STATEMENT, Peer reviewed