INVESTIGADORES
MARCHELLI Paula
artículos
Título:
Genetic diversity and differentiation in a southern beech subjected to introgressive hybridisation
Autor/es:
MARCHELLI, P; GALLO, L
Revista:
HEREDITY
Referencias:
Año: 2001 vol. 87 p. 284 - 293
ISSN:
0018-067X
Resumen:
Diversity and dierentiation among 11 Argentine populations of the South American southern beech,Nothofagus nervosa (Phil.) Dimitri & Milano, were studied using eight isozyme gene markers. Geneticdiversity, observed heterozygosity, mean number of alleles per locus, Gregorius' genetic distance,amount of genetic dierentiation and mean level of dierentiation among populations were estimated.Introgression of N. obliqua into the gene pool of N. nervosa was analysed using two species-speci®cisozyme gene markers (Adh-A and Pgi-B). As in most forest tree species, the main genetic variationwas found within populations. Mean observed heterozygosity for the species was 17.3%, whilst meanlevel of genetic dierentiation (dge) was 4.6%. The most dierentiated locus was Mdh-B withdierences in 10% of the eective number of genes. From the analysis of the species distributionpattern it is suggested that genetic variation is geographically structured through the dierent lakewatersheds along which the species is distributed. The occurrence of natural interspeci®c hybridiza-tion in some of the watersheds, together with the unidirectional gene ¯ow along these watershedssharpens this latitudinal structure. Dierent evolutionary stages in the introgressive hybridizationprocess are apparently taking place in dierent lake watersheds.