Allozyme diversity and genetic structure of marginal and central populations of Corylus avellana L. (Betulaceae) in Europe

• Published in: Plant systematics and evolution Vol. 244; no. 3/4; pp. 157 - 179
• Main Authors: Persson, H., Widén, B., Andersson, S., Svensson, L.
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.02.2004; Springer Nature B.V
• Subjects: Alleles; Betulaceae; Biologi; Biological Sciences; Corylus avellana; Ecology; Ekologi; Evolutionary genetics; Genetic diversity; Genetic drift; Genetic loci; Genetic structure; Genetic variation; Genotypes; Hazel; Heterozygosity; Loci; Natural populations; Natural Sciences; Naturvetenskap; Plants; Population genetics; Population mean; Population structure; Populations; Spatial distribution; Vegetative reproduction; Europe
• ISSN: 0378-2697; 1615-6110; 1615-6110; 2199-6881
• DOI: 10.1007/s00606-003-0073-3

Corylus avellana L. (hazel, Betulaceae) is a long-lived, widespread shrub in Europe, having its northern range margin in Fennoscandia and a postglacial history involving range-expansion from refugial areas in southern Europe. In this study, we tested for a relationship between marginality and low within-population genetic diversity by assessing patterns of variation at 14 putatively neutral allozyme loci (comprising 43 putative alleles) within and between 40 natural populations of C. avellana along a north-south transect in Europe. Geographically marginal populations (central Sweden) showed lower levels of within-population diversity than populations in more central regions, as indicated by significant negative correlations between latitude and the percentage of polymorphic loci (rS = -0.47, P < 0.001), the average number of alleles per locus (rS = -0.65, P < 0.001), the expected heterozygosity (rS = -0.19, P < 0.05), and the proportion of distinguishable genotypes (rS = -0.56, P < 0.001). These patterns, combined with the unusually high between-population component of gene diversity (GST = 19.7%) and allelic richness (AST = 24%) in the marginal region, can be attributed to historical bottlenecks during the species' postglacial range-expansion, but may also reflect a history of genetic drift in the small, isolated populations occupying the marginal region. Information on the spatial distribution of genotypes provide further support for a role of vegetative reproduction (layering) in the structuring of genetic variation within populations.