Spatial Distribution Patterns of Genetic Variation in Four Rhodiola Species: Testing the Centre‐Periphery Hypothesis

ABSTRACT Aim Understanding the spatial distribution of genetic variation is crucial for conservation biogeography. The centre‐periphery hypothesis (CPH) posits that central populations exhibit higher genetic diversity and lower differentiation. However, it remains unclear how species centre definitions and associated factors influence genetic variation patterns. Here, we evaluated CPH patterns across multiple centres in four Rhodiola species. Location Qinghai–Tibetan Plateau (QTP) and Hengduan Mountains (HDM). Methods We genotyped 1507 individuals from 65 populations of four Rhodiola species ( R. bupleuroides , R. discolor , R. fastigiata , and R. chrysanthemifolia ) using 12 microsatellite loci. We estimated geographical (geographical occurrence), ecological (current suitable areas), and historical (refugia) centres for each species. Generalised linear models were performed to test whether genetic variation followed CPH predictions. Finally, we used multiple approaches to investigate how geographical, ecological, and historical factors interactively shape genetic variation. Results Our results showed these centres did not completely coincide within each species. Consistent with CPH, geographically, ecologically, and historically marginal populations of R. fastigiata and R. chrysanthemifolia exhibited reduced genetic diversity and increased genetic differentiation. Genetic diversity decreased from central towards peripheral populations for ecological and historical centres for R. bupleuroides . R. discolor did not conform to CPH across the three centres. Although ecological factors explained much genetic variation in most species, they largely interacted with geographical and historical factors. The CPH patterns were associated with the differences in key environmental variables across central and peripheral populations. Main Conclusions Our results demonstrate the generality of the CPH, although specific patterns vary slightly across four Rhodiola species. Species‐specific genetic patterns are shaped by biological properties, and interactive geographical, ecological and historical factors, with environmental heterogeneity playing a particularly important role. This study expands our understanding of CPH and informs conservation strategies under ongoing climate change.