A multidisciplinary approach to the translocation of Primula palinuri Petagna, an Italian endemic species

This thesis focuses on the integrated conservation of Primula palinuri Petagna, a cliff-dwelling endemic species of southern Italy threatened by habitat loss and environmental stressors. Through a multidisciplinary approach combining genetic, ecological, and experimental studies, this work investigates the main biological and environmental factors influencing the species’ persistence. It supports the design of effective in situ and ex situ conservation actions. P. palinuri represents a key component of coastal biodiversity, whose presence is strongly influenced by habitat fragmentation processes, environmental stresses such as salinity and climatic fluctuations, and ecological interactions with soil and other ecosystem components. Previous studies have highlighted a limited integrated knowledge of the species’ biology, genetics, and ecology, thereby restricting targeted conservation efforts. By combining genetic data analysis, germination physiology, edaphic characterization, and ecological niche modeling, this work seeks to provide a solid multidisciplinary scientific basis to support future conservation and translocation activities, which are crucial to counteracting the decline of this emblematic Mediterranean species. First, the genetic analysis of P. palinuri populations allowed the assessment of intra- and inter-population genetic diversity and population structure. Results showed a moderate level of genetic diversity within populations, but a marked differentiation among populations indicative of strong habitat fragmentation. Some populations exhibited signs of inbreeding, suggesting a high risk of inbreeding depression that could compromise vitality and adaptive capacity. This fragmented genetic structure confirms the existence of distinct conservation units that must be carefully considered in the selection of donor populations. Proper identification of these units helps mitigate genetic erosion risks, ensuring that future translocation efforts can maintain or increase the genetic variability essential for the species’ long-term survival. Concurrently, the germination physiology of P. palinuri was investigated, focusing on the environmental factors affecting seed germination. Experiments conducted on different populations revealed that germination is influenced by multiple environmental factors. Alternating day/night temperatures significantly enhanced germination compared to constant temperatures, probably due to the small seed size of the species, as smaller seeds (<2 mg) are generally sensitive to thermal fluctuations. Light appears to play an important role in germination processes. Additionally, the imposition of water stress using PEG resulted in decreased germination rates as the concentration increased, with significant differences among populations; some exhibited higher tolerance to drought conditions. Sowing depth was another critical factor: seeds buried deeper showed reduced germination, likely due to the difficulty in overcoming the soil layer. Finally, salinity stress tests on two distinct populations, coastal and inland, demonstrated that the coastal population exhibited greater tolerance to high salinity levels, while the inland population showed marked germination decline with increasing salinity, indicating ecotypic adaptations related to the site of origin. These findings highlight the complex and population-specific environmental influences on P. palinuri germination, underscoring the necessity of incorporating such variables into effective propagation protocols for conservation purposes. Soil characteristic analyses at current P. palinuri growth sites provided detailed insights into the physical and chemical properties influencing seedling establishment and plant growth. Soils were generally poor in organic matter but well-aerated with a predominantly sandy texture favoring drainage. pH values remained slightly alkaline, consistent with the rocky coastal niches where the species thrives. Electrical conductivity, indicative of soil salinity, was moderate, confirming the species’ adaptation to the variable saline conditions typical of marine habitats. Furthermore, low levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs) were detected, indicating a relatively uncontaminated environment, an essential condition for the conservation of a sensitive species like P. palinuri. These results emphasize the importance of specific microsites, such as rocky niches with defined edaphic features, as key environments for species reintroduction and conservation. Through ecological niche modeling (ENM), the spatial distribution of P. palinuri was reconstructed for critical historical climatic periods, including the Last Interglacial, Last Glacial Maximum, and Mid-Holocene, providing an essential evolutionary perspective to understand species’ temporal changes. These historical reconstructions highlighted variations in habitat availability and quality, suggesting how the species adapted or contracted in response to past climatic shifts. Additionally, projections of future species distribution under various climate change scenarios were developed. These data represent a crucial tool for planning targeted translocation interventions, anticipating and mitigating environmental change impacts. The integration of genetic analyses, germination studies, soil characterisations, and ecological modelling offers a comprehensive and interdisciplinary framework that contributes to defining informed and adaptive conservation strategies for P. palinuri. This work lays an essential foundation for future ex situ and in situ conservation efforts, aiding the preservation of this iconic species in a rapidly changing environment.