Format: ORAL

Ins Gmez-Ramos1*,Ana Valds-Florido1, Sonia Merinero2,Enrique Maguilla3, Carmen Bentez-Bentez1, Pedro Jimnez-Mejas3, Luceo, Modesto3, Arroyo, Juan1, Marcial Escudero1

1 University of Sevilla, Seville, Spain 2 Rey Juan Carlos University, Móstoles, Spain 3 Pablo de Olavide University, Seville, Spain

Biologists have debated about how time scale affects evolutionary processes, since the first evolution theories. We present local and regional approaches on the evolution of a common species in the Palearctic (also in the eastern North America): Carex nigra (L.) Reichard. In each approach we have assessed which factors are more critical: current ecological conditions or historical processes? In the local approach, microsatellites were used to assess the genetic diversity and structure of 12 populations along an altitudinal gradient in SE Spain. The regional approach involved the application of RAD-seq to explore the phylogeography of Carex nigra. Niche modelling analyses were also conducted to evaluate the potential distribution of the C. nigra complex. At a local scale, microclimatic and edaphic conditions influenced genetic diversity among populations and shaped the plants reproductive strategy (clonality vs. sexual reproduction). Notably, lower genetic diversity was observed in colder and nutrient-poor environments where clonality predominated. The genetic structure exhibited a weak pattern, showing no correlation with either climate or geography. Results from the regional approach indicated a strong geographical structure within Carex nigra range, distinguishing between three subspecies: C. nigra subsp. intricata, subsp. nigra and subsp. transcaucasica, with almost non-overlapping distribution. The significant differences in their climatic niches are, likely, explained by their allopatric distribution pattern. At this scale, historical phylogeography emerge as the main driver of divergence, with these ranges coinciding with different climate refugia during the Pleistocene glaciations. The scale of the evolutionary process plays a crucial role in determining the importance of diversification drivers in Carex nigra. Historical phylogeographic factors, such as refugia during Pleistocene glaciations, wielded substantial influence at the regional level. In contrastmicroclimate and soil conditions did not contribute to population genetic differentiation acrossaltitudinal gradients in a Mediterranean mountain range but determined patterns ofgenetic diversity.