Browsing by Subject "DIVERSITY ANALYSIS"

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  • Shikano, Takahito; Järvinen, Antero; Marjamaki, Paula; Kahilainen, Kimmo K.; Merilä, Juha (2015)
    Variation in presumably neutral genetic markers can inform us about evolvability, historical effective population sizes and phylogeographic history of contemporary populations. We studied genetic variability in 15 microsatellite loci in six native landlocked Arctic charr (Salvelinus alpinus) populations in northern Fennoscandia, where this species is considered near threatened. We discovered that all populations were genetically highly (mean F-ST approximate to 0.26) differentiated and isolated from each other. Evidence was found for historical, but not for recent population size bottlenecks. Estimates of contemporary effective population size (N-e) ranged from seven to 228 and were significantly correlated with those of historical N-e but not with lake size. A census size (N-C) was estimated to be approximately 300 individuals in a pond (0.14 ha), which exhibited the smallest N-e (i.e. N-e/N-C = 0.02). Genetic variability in this pond and a connected lake is severely reduced, and both genetic and empirical estimates of migration rates indicate a lack of gene flow between them. Hence, albeit currently thriving, some northern Fennoscandian populations appear to be vulnerable to further loss of genetic variability and are likely to have limited capacity to adapt if selection pressures change.
  • Hilmarsson, Hrannar Smari; Hytonen, Timo; Isobe, Sachiko; Goransson, Magnus; Toivainen, Tuomas; Hallsson, Jon Hallsteinn (2017)
    The woodland strawberry, Fragaria vesca, holds great promise as a model organism. It not only represents the important Rosaceae family that includes economically important species such as apples, pears, peaches and roses, but it also complements the well-known model organism Arabidopsis thaliana in key areas such as perennial life cycle and the development of fleshy fruit. Analysis of wild populations of A. thaliana has shed light on several important developmental pathways controlling, for example, flowering time and plant growth, suggesting that a similar approach using F. vesca might add to our understanding on the development of rosaceous species and perennials in general. As a first step, 298 F. vesca plants were analyzed using microsatellite markers with the primary aim of analyzing population structure and distribution of genetic diversity. Of the 68 markers tested, 56 were polymorphic, with an average of 4.46 alleles per locus. Our analysis partly confirms previous classification of F. vesca subspecies in North America and suggests two groups within the subsp. bracteata. In addition, F. vesca subsp. vesca forms a single global population with evidence that the Icelandic group is a separate cluster from the main Eurasian population.