Data from: Extensive sympatry and frequent hybridization of ecologically divergent aquatic plants on the Qinghai-Tibetan Plateau

Hybridization has fascinated biologists in recent centuries for its
evolutionary importance, especially in plants. Hybrid zones are commonly
located in regions across environmental gradients due to more
opportunities to contact and ecological heterogeneity. For aquatic taxa,
intrazonal character makes broad overlapping regions in intermediate
environments between related species. However, we have limited information
on the hybridization pattern of aquatic taxa in alpines, especially
submerged macrophytes. In this study, we aimed to test the hypotheses that
niche overlap and hybridization might be extensive in related aquatic
plants across an altitudinal gradient. We evaluated the niche overlap in
three related species pairs on the Qinghai-Tibetan Plateau and assessed
the spatial pattern of hybrid populations. Obvious niche overlap and
common hybridization were revealed in all three pairs of related aquatic
plants. The plateau edge and river basins were broad areas for the
sympatry of divergent taxa, where a large proportion of hybrid populations
occurred. Hybrids are also discretely distributed in diverse habitats on
the plateau. Differences in the extent of niche overlap, genetic
incompatibility and phylogeographic history might lead to variations in
hybridization patterns among the three species pairs. Our results
suggested that plateau areas are a hotspot for ecologically divergent
aquatic species to contact and mate and implied that hybridization may be
important for the freshwater biodiversity of highlands.