Intra- and interspecific allozyme variability in Eurasian Larix Mill. species

Abstract

The variation at 15 allozyme loci was examined in 32 populations of Larix taxa across their range in northern Eurasia. Fifteen populations of L. sibirica Ledeb., six populations of L. gmelinii Rupr., three populations of L. olgensis A. Henry, two populations of L. decidua Mill., and one population each of L. cajanderi Mayr, L. kaempferi (Lamb.) Carr. (= L. leptolepsis (Sieb. et Zucc.) Endl.), L. kamtschatica (Rupr.) Carr., L. czekanovskii Szaf., L. amurensis Kolesn. and L. ochotensis Kolesn. were analysed. Interpopulational genetic differentiation within taxa was estimated with Wright's F(ST) and varied from 2.6 to 8.1% according to taxon. Highly significant allelic differentiation was detected with Fishers exact test. Genetic distances among L. sibirica populations were associated primarily with longitude. Allozyme frequencies changed gradually from the Urals eastward to Siberia, and eastern populations of L. sibirica are genetically more similar to L. olgensis than to western L. sibirica. Far-eastern populations of Larix species, morphologically similar to L. gmelinii and defined as L. cajanderi, L. amurensis and L. ochotensis, appear to be genetically dose to both L. gmelinii and to L. olgensis, suggesting that they originated through introgressive hybridization between these two species.