Margins of adaptation at the desert frontier: genetic responses of Ammopiptanthus mongolicus in arid northwestern China.

Background: Understanding plant adaptation to extreme environments is crucial for conservation and evolutionary biology. Ammopiptanthus mongolicus, a drought-resistant evergreen shrub native to northwestern China, provides an excellent model for studying genetic and ecological responses to arid conditions. Climatic fluctuations, especially during the Quaternary, have shaped its distribution and genetic diversity, influencing its ability to survive in desert environments. However, the mechanisms underlying its adaptation remain insufficiently explored.

Main body: We synthesize findings from previous genomic, ecological, and biogeographical studies to evaluate the adaptive mechanisms of A. mongolicus and assess the conservation implications for desert plant populations. Northwestern China encompasses vast arid regions characterized by extreme environmental conditions, including low precipitation, high evaporation rates, and significant temperature fluctuations. The uplift of the Qinghai-Tibet Plateau increased aridity by blocking moist air, leading to the transformation of humid forests into drought-resistant deserts. Ammopiptanthus mongolicus, a broad-leaved evergreen shrub, serves as a model for studying plant adaptation to arid environments. Genomic studies have identified several genes and pathways associated with drought and cold adaptation in this species. Core populations of A. mongolicus inhabit stable environments and exhibit high genetic diversity, whereas marginal populations endure extreme conditions and show strong local adaptations and distinct genetic traits. In this review, we hypothesize that the geographical distribution of core and peripheral populations may shift in response to future climate change, with peripheral populations potentially serving as sources of adaptive alleles for extreme climatic conditions.

Conclusions: Marginal populations of A. mongolicus are essential reservoirs of adaptive traits, providing genetic resources for coping with environmental stressors such as drought and cold. However, they face a higher risk of local extinction due to genetic load and habitat fragmentation. Gene flow between core and marginal populations may be crucial for maintaining genetic diversity and adaptive potential. Conservation strategies should prioritize protecting marginal populations to reduce genetic load, enhance resilience, and preserve genetic diversity in response to intensifying climate change.