Where evolution persists and diversifies: phylogenetic diversity and endemism in <i>Allium</i> subgenus <i>Melanocrommyum</i> (Amaryllidaceae)

Abstract Allium subgenus Melanocrommyum represents a major Eurasian lineage within Allium, yet its centres of diversity and endemism have not been evaluated using spatial phylogenetic approaches. Here, we analysed 4642 georeferenced occurrence records representing 170 taxa together with plastome- and ITS-based phylogenetic datasets to assess species richness, weighted endemism, phylogenetic diversity, phylogenetic endemism, relative phylogenetic endemism, categorical neo- and paleo-endemism, turnover, and environmental correlates of phylogenetic diversity. Our results confirm the Irano–Turanian region as the main evolutionary centre of Allium subg. Melanocrommyum, with the strongest concentration of species richness, phylogenetic diversity, and phylogenetic endemism in the Central Asian mountains, especially the Tian Shan and Pamir–Alay systems. These areas contain both high species numbers and geographically restricted evolutionary history, indicating their role as centres of diversification and long-term lineage persistence. Weighted endemism highlights additional narrow-range species centres in Central Uzbekistan (Kyzylkum, Navoi Region) and north-western Iran (Ardabil and East Azerbaijan provinces), showing that species-level endemism and phylogenetic endemism are not fully congruent. CANAPE identifies Central Asia mainly as a centre of paleo-endemism, whereas Western Irano–Turanian and Anatolian regions show more fragmented mixed-endemism patterns. Turnover analyses further reveal a strong west–east biogeographic structure across the range. Environmental models suggest that phylogenetic diversity is associated with intermediate climatic seasonality and solar radiation and tends to be lower in more wind-exposed areas. Overall, this study shows that conservation priorities in Allium subg. Melanocrommyum should integrate species richness, endemism, evolutionary history, and environmental context, with Mountains of Central Asia representing the most important reservoirs of irreplaceable evolutionary diversity.

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