Genome admixture among four hare species in Iberia: focus on the broom hare (Lepus castroviejoi)

Abstract

AbstractPleistocene climatic fluctuations have often driven range shifts and hybridization among related species, leaving present-day genomic footprints. In the Iberian Peninsula,Lepus timidus, after its post-deglaciation retreat, has left extensive mitochondrial DNA traces in three other hare species, but the genomic correlates and underlying biogeographic scenarios are still incompletely understood. This study focuses onLepus castroviejoi, endemic to the Cantabrian region, using its non-Iberian sister species,L. corsicanus, for comparison. By analyzing coalescent patterns from 10 genomes, we estimate that these species remained isolated since their divergence, around 50,000 years ago, consistent with their current allopatry. Further analyses with 25 additional genomes indicate that small fractions of theL. castroviejoigenome originate fromL. granatensis,L. timidus, andL. europaeus(0.72%, 0.08%, and 0.04%, respectively). Introgression dating based on tract lengths suggestsL. granatensiswas already admixed withL. timiduswhen it hybridized withL. castroviejoi, which could explain thegranatensis-timidusancestry tract junctions detected inL. castroviejoi. Genomic segments with such junctions contain genes enriched for cell signaling and olfactory receptor activity, possibly facilitating genetic exchange. This research demonstrates how genomic ancestry inferences can reveal complex multiway admixture histories and illuminate past biogeographic events.