Geographic isolation, ecological adaptation, and hybridization influenced fast divergence of a Solanaceae plant group from subtropical highland grasslands

Abstract

[EN] Several processes influence species establishment in nature, with evolutionary radiations playing a critical role in biodiversity evolution. Ecological adaptation, progenitor-derivative speciation, pollinator shifts, and geographic isolation followed by local adaptation can lead to plant radiations in montane systems. This study investigated the rapid divergence and migration of highland Petunia species. Employing reduced representation genome sequencing and a genomic population approach, we focused on detecting structuration, ecological inference, hybridization/introgression, and evolutionary patterns. Our findings revealed an intricate and complex array of factors, including ecological adaptation without marked genetic diversity, hybridization, and geographic isolation, which led to species divergence in a short period. Ancestral polymorphism sharing maintained genetic diversity could facilitate rapid divergence among the highland species by providing variation to natural selection. During the Pleistocene, Petunia species expanded and contracted their ranges in response to the alternance of climate cycles. This period of environmental changes was pivotal in promoting rapid speciation through geographic isolation. Here, we highlight the multifaceted nature of species diversification, influenced by a confluence of geographic distribution, demographic history, and hybridization. The interplay of these factors highlights the diverse and dynamic pathways to speciation in a model plant genus, thereby contributing to a deeper understanding of species diversification and the role of genetic and environmental factors in shaping biodiversity.