Genetic diversity in Nothofagus nervosa detected with cpDNA, isozyme and adaptive traits and its implication for conservation strategies in Patagonian National Parks

MARCHELLI, P; GALLO, L A

Alcalá de Henares, España

Congreso; IUFRO Working Groups 2.04.01 (Population, ecological and conservation genetics) and 2.04.10 (Genomics).; 2006

IUFRO

Nothofagus nervosa (Phil.) Dim et Mil is a deciduous, anemophilous and anemochoric southern beech endemic to Chile and Argentina in southern South America. It occurs in the Andes and Pacific Coastal Mountains between 35º and 41º S. In Argentina the distribution is narrow and fragmented following the west-east oriented glacial valleys. Due to its valuable wood, N. nervosa was overexploited in the past and several populations were drastically reduced, especially in Chile. As it is usually the rule, the genetic variation of the species was not taken under consideration when protected areas were established. In Argentina, where the whole distribution range of N. nervosa lies within two National Parks, the definition of Evolutionary Significant Units is under consideration and therefore genetic studies have begun. The main objective of the present work is to study the genetic variation of Nothofagus nervosa through different neutral markers and also through adaptive traits such as seedling height in order to contribute with the design of conservation strategies. Seeds from a total of 20 populations covering the entire geographical range of the species in Argentina were collected. Both uniparentally (cpDNA) and nuclear (isozymes) inherited markers were analysed (eight isozyme loci and two cpDNA fragments (PCR-RFLP)). Seedling height was measure from provenance trials installed in the field. Relatively high levels of genetic diversity and differentiation were detected with the nuclear markers (AL = 3.38; Ho = 0.16; He= 0.18; d = 0.047 (FST = 0.052)). Genetic distances between neighbour populations was significantly different indicating high genetic differentiation and probably low levels of gene flow. Three cpDNA haplotypes were identified with the two primer/enzyme combinations scored. Only three populations showed intra-population variation and a high gene differentiation (GST = 0.868) was observed. Moreover, the haplotypes showed a highly structured geographic distribution with a north-south variation. Seedling height at the age of five years was variable among populations ranging from 73.2 to 153 cm (average 115.6 cm). One population (Hua Hum) showed the highest levels of diversity with both markers, and average values for seedling height. This population was under management since within National Parks some buffer areas are allowed for logging. Given the results of the present study, the authorities of the National Park Administration changed the protection status of the mentioned population and prohibited logging within it. It constitutes the first case in Argentina where genetic studies were taken into account to decide conservation priorities.