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Abstract Gene flow between cultivated and wild gene pools is common in the contact zone between agricultural lands and natural habitats and can be used to study the development of adaptations and selection of novel varieties. This is likely the case in the northern Adriatic region, where centuries-old cultivated orchards of sweet chestnut (Castanea sativa Mill.) are planted within the natural distribution area of the species. Thus, we investigated the population structure of several orchards of sweet chestnuts. Furthermore, the genetic background of three toponymous clonal varieties was explored. Six genomic simple sequence repeat (gSSR) and nine EST-derived SSR (EST-SSR) loci were utilized in this research, and both grafted and non-grafted individuals were included in this study. Five closely related clones were identified, which represent a singular, polyclonal marron variety, found in all three cultivation areas. Furthermore, many hybrids, a result of breeding between cultivated and wild chestnuts, have been found. Analyzed semi-wild orchards defined by a diverse genetic structure, represent a hotspot for further selection and could result in creation of locally adapted, high-yielding varieties.

Abstract Immortelle (Helichrysum italicum (Roth) G. Don; Asteraceae) is a perennial plant species native to the Mediterranean region, known for many properties with wide application mainly in perfume and cosmetic industry. A total of 18 wild H. italicum populations systematically sampled along the eastern Adriatic environmental gradient were studied using AFLP markers to determine genetic diversity and structure and to identify loci potentially responsible for adaptive divergence. Results showed higher levels of intrapopulation diversity than interpopulation diversity. Genetic differentiation among populations was significant but low, indicating extensive gene flow between populations. Bayesian analysis of population structure revealed the existence of two genetic clusters. Combining the results of F ST - outlier analysis (Mcheza and BayeScan) and genome-environment association analysis (Samβada, LFMM) four AFLP loci strongly associated with the bioclimatic variables Bio03 Isothermality, Bio08 Mean temperature of the wettest quarter, Bio15 Precipitation seasonality, and Bio17 Precipitation of driest quarter were found to be the main variables driving potential adaptive genetic variation in H. italicum along the eastern Adriatic environmental gradient. Redundancy analysis revealed that the partitioning of genetic variation was mainly associated with the adaptation to temperature oscillations. The results of the research may contribute to a clearer understanding of the importance of local adaptations for the genetic differentiation of Mediterranean plants and allow the planning of appropriate conservation strategies. However, considering that the identified outlier loci may be linked to genes under selection rather than being the target of natural selection, future studies must aim at their additional analysis.

Abstract Range contraction and habitat fragmentation can cause biodiversity loss by creating conditions that directly or indirectly affect the survival of plant populations. Fragmented habitats can alter pollinator guilds and impact their behavior, which may result in pollen/pollinator limitation and selection for increased selfing as a mechanism for reproductive assurance. We used Salvia brachyodon, a narrowly distributed and endangered sage from eastern Adriatic, to test the consequences of range contraction and habitat fragmentation. Molecular data indicate a severe and relatively recent species range reduction. While one population is reproductively almost completely isolated, moderate gene flow has been detected between the remaining two populations. The high pollen-to-ovule ratio and the results of controlled hand pollination indicate that S. brachyodon has a mixed mating system. Quantitative and qualitative differences in the community and behaviour of flower visitors resulted in limited pollination services in one population where no effective pollinator other than pollen and nectar robbers were observed. In this population, self-pollination predominated over cross-pollination. Various environmental factors, in which plant-pollinator interactions play a pivotal role, have likely created selection pressures that have led to genetic and phenotypic differentiation and different resource allocation strategies among populations.

Abstract Studying the population-genetic and phylogeographic structures of a representative species of a particular geographical region can not only provide us with information regarding its evolutionary history, but also improve our understanding of the evolutionary processes underlying the patterns of species diversity in that area. By analysing eight highly polymorphic microsatellite loci and two chloroplast DNA regions, we have investigated the influence of Pleistocene climate fluctuations on the evolutionary history of Salvia officinalis L. (common sage). The populations with the highest genetic diversity were located in the central parts of the Balkan distribution range. A large group of closely related haplotypes was distributed throughout the Balkans and the central Apennines, while the private lineage occupied the southern Apennines. In addition, two highly differentiated lineages were scattered only over the Balkans. The results suggest that a single refugium of the studied species from the last glacial period was located in the central part of the range in the Balkans. Numerous microrefugia, probably spanning several glaciation cycles, were scattered across the Balkans, while colonisation of the Apennines from the Balkans occurred at least on two occasions.