Geographical patterns of isozyme variation in mediterranean populations of perennial ryegrass

Abstract

Twenty-four natural populations of perennial ryegrass, sampled from the Mediterranean area (Italy, Corsica, Sardinia, South of France), have been studied for allelic variation at 13 enzyme loci. The total genetic diversity results mainly from the within-population component whereas a part of the between-population component can be explained by the geographical origins of the populations. Relationships between accessions have been studied using cluster and multivariate analyses such as principal component and discriminant analyses. Finally, the frequency and distribution of the most discriminating allele have been represented on geographic maps. The results indicate that Corsican populations are similar to Italian accessions whereas both French and Sardinian populations differ from all the others. The origins and relationships between each geographical group of accessions are discussed and, taking historical factors into account, we can suggest that Corsican populations have been introduced from Italy to the eastern side of the island. © 1994 The Genetical Society of Great Britain.