  Understanding the combined effects of climate change and habitat
fragmentation on the adaptive potential of plant populations is essential for
devising effective conservation strategies. This is particularly important
where mating system variation impacts the evolutionary consequences of habitat
fragmentation. Here we aimed to reveal how habitat fragmentation and climate
adaptation jointly influence the evolutionary trajectories in Primula elatior,
a heterostylous self-incompatible and dispersal-constrained forest herb. We
quantified the genomic variation and degree of herkogamy, a floral trait
reducing self-pollination, across 60 geographically paired populations of
Primula elatior across Europe, each pair featuring contrasting levels of
habitat fragmentation. Our findings revealed a large and unique set of adaptive
outliers in more fragmented landscapes, compared to high-connectivity ones,
despite the geographic proximity of the sampling pairs. This suggests elevated
selective pressures in fragmented habitats, mirrored by a reduced adaptive
potential to cope with climate change. Finally, a minority of genetic variants
associated with herkogamy were influenced by current levels of habitat
fragmentation and population size, potentially signalling early indicators of
evolutionary mating system changes in response to pollinator limitation.
Because evolutionary trajectories and adaptive potential are expected to be
increasingly affected by habitat fragmentation, our findings underscore the
importance of considering both habitat fragmentation and climate adaptation in
conservation research and planning.
