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Background: Together with other elevated areas, the Mountains of Central Asia are significantly threatened by ongoing climate change. The presence of refuges during the glaciations makes the region extremely rich in species, especially endemic ones. However, the limited potential for colonisation of other habitats makes rocky-related species with 'island‐like' distribution, particularly vulnerable to climate change. To understand the processes underlying species response to climate warming, we assessed differences in ecological niches and phylogenetic relationship of two geographically disjunctive alpine species belonging to the genus Sergia. The taxa are considered Tertiary relicts, endemic to the Tian Shan and Pamir-Alai Mountains. To illustrate range dynamics and differences in occupied niches of Sergia species, we used Ecological Niche Modelling of current and future distribution. Whereas, to reconstruct the phylogenetic relationship within and between Sergia and other related Campanulaceae species from the region we used molecular data (ITS, cpDNA, DArTseq-derived SNPs). Results: The results reveal that the genus Sergia is a polyphyletic group, and its representatives differ geographically, ecologically and genetically. Both S. regelii and S. sewerzowii constitute a common clade with Asyneuma group, however, S. sewerzowii is more closely related to Campanula alberti (a species that has never previously been considered closely related to the genus Asyneuma or Sergia) than to S. regelii. Sergia sewerzowii is adapted to lower elevations with higher temperatures, while S. regelii prefers higher elevations with lower temperatures. The future distribution models demonstrate a dramatic loss of S. regelii range with a shift to suitable habitats in higher elevations, while the potential range of S. sewerzowii increases and shifts to the north. Conclusions: This study shows that S. regelii and S. sewerzowii have a long and independent evolution history. Sergia regelii and S. sewerzowii significantly differ in realised niches. These differences are mirrored in the response of the studied endemics to future climate warming. As suitable habitats shrink, rapid changes in distribution can lead to species' range loss, which is also directly related to declines in genetic variability. The outcomes of this paper will help to more precisely assess the impact of climate changes on rocky-related plant species found in this world's biodiversity hotspot. [ABSTRACT FROM AUTHOR]

Aim: Past climatic oscillations are the main driving force of evolutionary changes in alpine species. Species' response to paleoclimatic oscillations is crucial in forecasting their future response in face of climate warming. The aim of this research is to explore the effect of climatic fluctuations on the evolutionary history, demography, and distribution of high‐mountain bellflowers (Campanula lehmanniana complex), the flagship and taxonomically problematic members of chasmophytic vegetation within an underexplored biodiversity hotspot, the Mountains of Central Asia. Location: Central Asia (Tian Shan, Alai and Zeravshan‐Hissar Mountains). Methods: We used molecular data (ITS, cpDNA, DArTseq‐based SNPs) of 262 individuals (70 for the phylogeny reconstruction, and 247 from 31 localities for population studies). We analysed the data using phylogenetic and molecular clock reconstructions, coalescent simulations, and ecological niche modelling. Results: Tertiary isolation between the Tian‐Shanian and Pamir‐Alaian populations led to the differentiation of the two main lineages (~5–6 Mya) corresponding to C. eugeniae and C. lehmanniana, whereas further Quaternary isolation into subregions led to intraspecific genetic differentiation, which starts almost simultaneously for both species (~2.7–1.5 Mya). The relatively small genetic admixture among populations indicates rare historic events of connectivity. In response to Holocene warming, the analysed species experienced a substantial decline in effective population size. Currently, the distribution of both taxa is highly influenced by precipitation in the coldest and driest quarters. Main Conclusions: Our results highlight a general principle that glacial–interglacial cycles and contemporary island‐like habitats distribution, shape the genomic variation of high‐mountain species. The similar declining demographic trend of examined taxa may suggest the overall response to ongoing climate warming. The results underline also the urgent need for conservation action in alpine regions to preserve their biodiversity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Global warming is the main threat to cold-adapted plants in mountain hotspots. • Past climate affects demographic history and current distribution of mountain plants. • Geographic vicariants variously respond to forecasted climate changes. • S. gracilis and S. zeravshanica are neoendemics originated in the late Pleistocene. • Predicted climate warming threatens rocky vegetation in the western Pamir-Alai Mts. Understanding species distribution, genetic diversification and evolutionary history is extremely important for mountainous regions with a high diversity of endemic species, which are particularly sensitive to climate change. In this study, we use environmental and molecular data obtained from genome-wide analyses to infer the genetic variability, demographic processes, and response of the cold-adapted, endemic geographical-vicariants Stipa gracilis (distributed in the Tian Shan Mts) and S. zeravshanica (distributed in the western Pamir-Alai Mts) to Quaternary climatic oscillations in a Central Asian mountain biodiversity hotspot. Genomic-based reconstructions of demographic history indicate that the examined endemics presented larger effective population sizes during the Last Glacial Maximum (LGM) period and experienced parallel demographic declines afterward. The results of fastSTRUCTURE analysis revealed three genetic clusters within S. gracilis populations and two within S. zeravshanica. The past distribution models reveals the glacial connectivity of both species, resulting in the detection of an admixture of S. zeravshanica genes in the specimens from the westernmost 'Alaian' population of S. gracilis. Although the occurrence of both species is closely associated with calcareous rocks, the differences in the ranges of the species distributions depend mostly on climatic factors, especially temperature and precipitation. The wider realized ecological niche of S. gracilis allows it to better adapt to global warming and potentially extend its range in the future, while S. zeravshanica , with its narrower niche, is more susceptible to environmental changes and potentially at risk of extinction. The findings will contribute to a better understanding of the factors shaping the distribution and genetic differentiation of mountain endemic species and provide a theoretical basis for their conservation by identifying areas sensitive to climate change in biodiversity hotspots. [ABSTRACT FROM AUTHOR]