Reproductive biology of endemic species and plant-insect relationships in a Global Change perspective

Endemic plant species are generally at greater risk of extinction due to their intrinsic characteristics. They typically have a restricted geographical range and possess specific stress-tolerant adaptations. While these adaptations allow them to occupy distinct ecological niches and avoid competition, they also make endemic species highly dependent on specific environmental conditions. In the context of significant global change, conserving these species has never been more urgent. To implement appropriate population management and conservation measures, we must deepen our understanding of the fundamental aspects of population persistence. Two of these key aspects are reproductive biology and interaction with other organisms. For most angiosperms, interaction with pollinators is particularly crucial; and given the ongoing global decline of pollinators, further investigation becomes increasingly essential for developing effective conservation frameworks. This study investigated the reproductive biology and pollination ecology of three endemic plant species: Santolina ligustica, Campanula sabatia and Gentiana ligustica. The first species is a narrowly distributed endemic found in eastern Liguria. The other two species are endemic to the southwestern Alps and have a more extensive range. Their reproductive output was studied under natural conditions and following tests on the flowers to investigate their mode of reproduction. Germination tests were also carried out on S. ligustica at various temperatures to determine the germination rate and speed under different conditions. Furthermore, the identity and frequency of flower visitors were studied through direct observations. Additionally, the pollination network of C. sabatia was examined before and after its reintroduction to a Special Area of Conservation (SAC). The effect of reintroduction on pollinator alpha and beta diversity, as well as on the distribution of pollinator abundance, was assessed. The role of the focal species within the network was also investigated. All the study species were found to depend on pollinators for seed production, which, highlighting the importance of plant-insect interactions. After being introduced, C. sabatia successfully integrated into the pollination network, attracting a diverse range of pollinators without radically altering the network's structure or diversity. This was observed to enhance the network's structural and functional complexity. These results emphasise the need to integrate reproductive biology and pollination network approaches into conservation strategies for endemic plant species.