Combining microsatellites, growth, and adaptive traits for managing in situ genetic resources ofEucalyptus urophylla

Abstract

Genetic diversity and structure of 17 populations representative of the natural range of Eucalyptus urophylla S.T. Blake in Indonesia were analysed with 10 microsatellite markers. Two provenance and progeny trials, using the same populations, were established in the Republic of the Congo and analysed for growth and survival at 37 months. Observed microsatellite heterozygosity (Ho) was moderate to high within populations (Ho= 0.51–0.72). The index of fixation (FIS) was significantly different from zero for all populations (FIS= 0.13–0.31) and possibly resulted from a Wahlund effect. The differentiation parameter was low (FST= 0.04) and not significantly different from zero, which can be explained by effective gene flow via pollen. The genetic variances within and among provenances for survival and growth traits were significantly different from zero, representing 13%–23% and 14%–50% of the total variation, respectively. The differentiation between populations based on quantitative traits was marked (QST= 0.07–0.33). A negative relationship between altitude of the seed source and its performance in the Congo was observed (R2= 0.59–0.67) and could be explained by the effect of natural selection along the altitudinal gradient. This marked differentiation for quantitative traits despite high apparent gene flow results in a clinal variation, which suggests the use of altitude of seed source as an important principle for in situ or ex situ management of E. urophylla genetic resources.