Data from: Rapid radiation of a plant lineage sheds light on the assembly of dry valley biomes

Southwest China is characterized by high plateaus, large mountain
systems, and deeply incised dry valleys formed by major rivers and their
tributaries. Despite the considerable attention given to alpine plant
radiations in this region, the timing and mode of the diversification of
the numerous plant lineages in the dry valley habitat remains unknown. To
address this knowledge gap, we investigate the macroevolution of Isodon
(Lamiaceae), a lineage commonly distributed in the dry valleys in
southwest China and wetter areas of Asia and Africa. We reconstructed a
robust phylogeny encompassing nearly 90% of the approximately 140 extant
Isodon species using transcriptome and genome-resequencing data. Our
results suggest a rapid radiation of Isodon during the Pliocene that
coincided with a habit shift from herbs to shrubs and a habitat shift from
humid areas to dry valleys. The shrubby growth form likely acted as a
preadaptation allowing for the movement of Isodon species into these
valleys. Ecological analysis highlighted aridity and precipitation as key
factors influencing the niche preferences of different growth forms and
species richness of Isodon. Integrating our results with insights from
tectonic movements in the Tibetan Plateau and adjacent regions, we infer
that the interplay between topography and the evolution of the East Asian
monsoon since the middle Miocene likely contributed to the formation of
the dry valley biome in southwest China. This study enhances our
understanding of evolutionary dynamics and ecological drivers shaping the
distinctive flora of this region.