The effect of different glaciation patterns over the current genetic structure of the southern beech Nothofagus antarctica

PASTORINO MJ; MARCHELLI, P.; MILLERÓN, M.; SOLIANI, C.; GALLO LA

GENETICA

SPRINGER

Lugar: Berlin; Año: 2009 vol. 136 p. 79 - 89

0016-6707

Different regional patterns of glaciation areexpected to have brought about a differential effect on thepresent genetic structure of natural tree populations in thetemperate regions. The aim of the present study is to testthis hypothesis in Nothofagus antarctica, a key tree speciesof the temperate forests of southern South America. Analmost continuous ice layer characterized the region of theAndes south of 41S, while towards northern latitudes thepattern was more fragmented. Therefore, a higher chancefor the location of larger or more numerous glacial refugesin the north of the Argentinean range, leads us to predict ahigher genetic diversity in this region. Twelve naturalpopulations of N. antarctica were sampled along thenorthern half of its Argentinean range, including six above41S and six below that latitude. Sampled populations weregenetically characterized through cpDNA and isozymegene markers. Both groups of populations were comparedby means of several diversity and differentiation parameters.A genetic structure analysis was conducted withisozyme data through clustering and Bayesian approaches.Based on three polymorphic chloroplast regions, only twohaplotypes were distinguished, one corresponding to thenine northernmost sampled populations and the other to thetwo southernmost ones. Only the population locatedbetween those two groups resulted polymorphic. AMOVAanalyses also revealed a latitudinal genetic structure for thepopulations surveyed, and higher levels of genetic variationwere recognized in the northern populations.