DIFFERENTIAL IMPACTS OF HABITAT FRAGMENTATION ON GENETIC STRUCTURE OF TWO IMPORTANT RIPARIAN SPECIES (SALIX ALBA & POPULUS NIGRA)

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2022-2-23
Durgut, Bilge
Salix alba and Populus nigra are two important tree species of riparian ecosystems. With a great ecologic and economic significance, they are naturally distributed in almost all river basins of Turkey. The genetic structures of these species in two river basins in Turkey were studied using eight common microsatellite markers to both species to reveal the impacts of habitat fragmentation. Therefore, the studied rivers were selected to represent a highly fragmented river, and a protected river from habitat fragmentation which are respectively Kızılırmak River and Melendiz River of Ihlara Valley. For the study, 132 S. alba and 84 P. nigra genotypes were sampled from four different populations of Kızılırmak while 29 S. alba and 25 P. nigra genotypes were sampled from Ihlara. Various population genetics analyses were performed with the obtained data to evaluate the efficiency and diversity of microsatellite loci, genetic diversity and structure of the populations of two species, effects of habitat fragmentation, and other possible human-related activities on these species. The results of these analyses demonstrated that habitat fragmentation and other human-mediated activities had important effects on the genetic structures and diversities of both species. Differentially, P. nigra was detected as it was affected by these human activities more than S. alba. The reason behind this is that P. nigra has been more commonly transported by humans and commercially cultivated in Anatolia by comparing to S. alba. The results indicate that the expected diversity levels were low (mean uHe values are 0.61 for S. alba and 0.59 for P. nigra) and the excess of observed heterozygosity levels was found (mean Ho values are 0.63 for S. alba and 0.87 for P. nigra). This suggests the recent bottleneck events causing the loss of allelic diversity in both species. The difference between Ho and uHe values was greater for P. nigra while these values were closer to each other for S. alba. It seems the populations of S. alba were close to the Hardy-Weinberg equilibrium which could be caused by less severity of past experienced bottleneck events of the species. Furthermore, the differentiation between Kızılırmak and Ihlara populations was found to be highly significant for both species (FST values are 0.05 and 0.14 for S. alba and P. nigra, respectively). Four populations of Kızılırmak were also differentiated from each other significantly for both species (FST values are 0.02 for both S. alba and P. nigra). This difference between the FST values also points out the wild nature of S. alba populations is still maintained, but the high vulnerability of P. nigra populations to habitat fragmentation and other human-related activities. Genetic resources of these two important species of riparian ecosystems need to be protected from unregulated human activities including habitat destruction and fragmentation caused by several agricultural and urbanization practices, and improper afforestation and cultivation policies. The information generated from this study is valuable for developing both successful conservation and breeding programs, and new ways to decrease the negative impacts of habitat fragmentation on these two species.

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Citation Formats
B. Durgut, “DIFFERENTIAL IMPACTS OF HABITAT FRAGMENTATION ON GENETIC STRUCTURE OF TWO IMPORTANT RIPARIAN SPECIES (SALIX ALBA & POPULUS NIGRA),” M.S. - Master of Science, Middle East Technical University, 2022.