Species-specific drivers of genetic diversity are decoupled from landscape connectivity and plant community diversity

Understanding how habitat connectivity shapes biodiversity remains a major ecological challenge. In particular, the roles of connectivity and ecological heterogeneity in co-variation between plant species diversity and intraspecific genetic diversity are not well understood. We combined species distribution modelling, resistance-to-movement mapping, landscape connectivity analysis and population genomics to investigate diversity patterns in three wet-meadow herbs, Scorzonera humilis, Oenanthe peucedanifolia and Lychnis flos-cuculi, and their surrounding plant communities. Connectivity inferred from species distribution models was similar across species, but it did not correlate with plant community diversity. Some connectivity metrics explained genetic diversity, but only in O. peucedanifolia. Interestingly, environmental drivers of genetic differentiation were highly species-specific despite spatial co-occurrence. Furthermore, genetic diversity of two of the three species changed with the presence of some species in the community, but it was consistently unrelated to local plant community diversity. Overall, the processes shaping within-species biodiversity may differ fundamentally from those structuring metrics of habitat connectivity and plant species diversity, with important implications for conservation.