Format: ORAL

Guillermo Santos Rivilla.1,Mario Mairal 1, Cornelia Krause2, Sonia Molino de Miguel 1 3, Anita Roth-Nebelsick2, Mike Thiv2and Mario Fernndez-Mazuecos4.

1 Universidad Complutense de Madrid. Madrid. Spain 2 Natural History Museum Stuttgart. Stuttgart. Germany 3 Universidad Europea de Madrid. Spain 4 Universidad Autónoma de Madrid. Madrid. Spain

Climatic refugia, deemed as natural laboratories for investigating species responses to historical climatic shifts, offer valuable perspectives into the evolutionary dynamics of floras. The Palaeotropical flora, originating in the northern hemisphere during pre-Quaternary times, is believed to have endured in microclimatic subtropical zones across Europe and the Macaronesian islands. This research focuses on Woodwardia radicans (Blechnaceae), a fern historically recognized as a Palaeotropical relict, thriving in the Macaronesian archipelagos and southern Europe, particularly the northern Iberian Peninsula. Employing the genotyping by sequencing (GBS) technique, we scrutinized the genetic and phylogeographic patterns of northern Iberian populations and estimated times of lineage divergence. Despite the species having diverged from its sister, W. unigemmata, around the Pliocene, European populations diverged in the Quaternary, challenging the presumed pre-Quaternary relict status of these continental populations. Population-level analyses of the northern Iberian Peninsula reveal low genetic diversity and noteworthy differentiation among populations. Our findings challenge the assumed pre-Quaternary relict status of continental populations, indicating a Quaternary recolonization from Macaronesia. The absence of a distinct phylogeographical pattern in the northern Iberian Peninsula is attributed to fragmentation and genetic drift, signaling a departure from a more widespread distribution range in the late Quaternary. Beyond illuminating the biogeographic history of this unique species, our results yield crucial insights for defining conservation strategies. The study underscores the imperative to reassess assumptions about the historical persistence of Palaeotropical species in subtropical environments and emphasizes the significance of considering late Quaternary dynamics in comprehending current genetic and phylogeographic patterns.