Livin’ on the edge. A case study on gene flow restoration for the endemic species Primula palinuri Petagna with a fragmented habitat

The restoration of gene flow among fragmented populations represents a key challenge in contemporary conservation biology. This study proposes an integrative methodological framework for in situ conservation of rare and threatened plant species, using the Mediterranean paleoendemic Primula palinuri Petagna as a case study. The species, currently listed as endangered, is confined to coastal cliffs along the Tyrrhenian coast of southern Italy, where habitat fragmentation, anthropic pressures and limited dispersal have led to population isolation. To assess the current genetic and ecological status of P. palinuri, three complementary approaches were combined: single nucleotide polymorphism (SNP) genotyping, environmental DNA (eDNA) analysis, and ecological niche modelling (ENM) using MaxEnt. SNP data revealed low heterozygosity and high inbreeding coefficients, confirming restricted gene flow among populations. eDNA metabarcoding of floral samples identified a diverse assemblage of interacting arthropods, including potential pollinators such as Melanostoma scalare and M. mellina, whose limited flight ranges (< 2 km) may further constrain inter population connectivity. ENM indicated that temperature-related variables are the primary factors shaping the distribution of P. palinuri and enabled the identification of approximately 40 km² of suitable areas, both within and beyond the species’ current range, that could support the potential reintroduction of individuals aimed at reconnecting existing populations. The integration of genomic, ecological, and environmental tools provides a powerful approach for guiding restoration and management actions. This framework offers a transferable model for conserving plant species inhabiting fragmented habitats, bridging genetic diversity, species ecology, and habitat suitability within a unified in situ conservation strategy.