Document: MAD-3-99-107

Genetic diversity and water stress in isolated Negev desert populations of Acacia raddiana.

SHRESTHA, M.K.*, D.WARD and A.GOLAN-GOLDHIRSH

Ben-Gurion University of the Negev, Sede Boqer 84990 Israel ¹

Abstract:
There is widespread concern over mortality of native Acacia trees in the Negev desert, Israel. Mortality varies widely, and may reach as high as 61% in populations of adult trees. The threat of extinction is becoming evident in these Acacia spp. due to high mortality and rare recruitment of seedlings. It is hypothesized that diminished genetic diversity has resulted from decline of these populations. The present study focused on Acacia raddiana because it is the most widespread species among the three native Acacias. We selected five sites with the highest mortality and three sites with the lowest mortality out of 75 sites surveyed. Random Amplified Polymorphic DNA (RAPD) markers were used to assess the relationships and genetic diversity among these populations. We investigated whether mortality is related to current water stress in these populations using a Scholander pressure chamber. There was considerable genetic variability among populations and a high degree of polymorphism within populations. Low genetic polymorphism was not associated with high mortality populations. We found that high mortality populations had significantly more negative water potentials than low mortality populations. There was a negative correlation between water stress and genetic polymorphism, indicating that genetic polymorphism may be important in withstanding environmental stress.

Keywords: Acacia

This abstract is being presented at: 10:30 AM in session:
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