Fuente: PubMed "pollen" Ecol Evol. 2026 Jul 29;16(8):e74043. doi: 10.1002/ece3.74043. eCollection 2026 Aug.ABSTRACTViola hybanthoides is a narrowly endemic species restricted to two isolated danxia landscapes (Pingshi and Mount Danxiashan) in Southeast China, serving as an ideal model for studying endemism in fragmented habitats. Using ddRAD-seq and shallow genome sequencing, we genotyped 156 individuals from 13 populations of the species to explore its genetic patterns and evolutionary processes. Results showed extremely low within-population genetic diversity (H E = 0.058 ± 0.028), probably driven by limited pollen and seed dispersal ranges, recurrent founder events, and persistent genetic drift exacerbated by post-glacial population contractions. Pronounced genetic differentiation existed between Pingshi and Danxiashan, with Danxiashan populations showing an east-west split by the Jinjiang River. Admixture analysis and plastid phylogeny identified one population of Pingshi as a hybrid population between Danxiashan and Pingshi. Combined with population dynamics and fastsimcoal2 inference, it is inferred that V. hybanthoides expanded during glacial periods and contracted to refugia in interglacials, with Danxiashan populations spreading northwestward to Pingshi in glaciations, giving rise to secondary contact and hybrid lineages. Thus, the species faces threats including depleted genetic variation, severe habitat fragmentation, and human-exacerbated historical bottlenecks. We propose targeted conservation strategies, including prioritized in situ protection of core genetically representative populations, population reinforcement via tissue culture and reintroduction, and long-term multi-indicator population dynamic monitoring. This study elucidates how Quaternary climate fluctuations and danxia topographic isolation jointly shape the genomic differentiation of endemic plants and provides population-genomic references for biodiversity conservation in fragmented edaphic island ecosystems.PMID:42529414 | PMC:PMC13416757 | DOI:10.1002/ece3.74043