Merging Ajaniopsis (Asteraceae), an endangered genus endemic to the Tibet Plateau, into Artemisia: Implications for systematics and conservation

Ajaniopsis is a monotypic genus of Asteraceae endemic to the Tibetan Plateau, growing on alpine scree slopes. It has been widely recognized as a separate genus and employed in many evolutionary and ecological analyses for its unique morphological characters. Despite being treated as an endangered species and once included in lists of key protected plant species, its systematic position has never been critically evaluated in a phylogenetic context. Furthermore, neither its past nor future distributional range has been assessed or predicted. In this study, we undertook morphological and molecular investigations to elucidate its systematics, and employed niche modeling to evaluate its historical, current, and potential future distributional range. Our phylogenetic analyses, based on the plastid genome and two nuclear DNA regions, show that Ajaniopsis is deeply nested in the mega-diverse genus Artemisia. Morphological analysis indicates that its unique characters are also present in many distantly related species of Artemisia, implying significant convergent evolution. Consequently, Ajaniopsis can be reduced into Artemisia rather than being considered a distinct genus. Niche modeling reveals that its distributional range underwent a dramatic contraction ca. 3.3 Ma and is likely to continue shrinking in the future. This dramatic range contraction might be associated with climate changes and human activities in its unique habitat. Therefore, immediate in situ conservation is imperative for this critically endangered species, necessitating the establishment of a nature reserve on the Tibetan Plateau. Our studies highlight that it is beneficial to explore the evolutionary history of endangered species in detail when drafting conservation strategies.