Discussion
The aim of this study was to determine the drought tolerance of a
diverse array of Hakea species to test prediction based on
climate-origin and life-history. Sampling 16 Hakea species
representing a wide range of climatic niche and life history traits from
common conditions estimated genetically determined trait variation. Our
results revealed that there was significant variation in the drought
tolerance of congeneric species and that biome/climate (rainfall and
aridity) of origin was the key predictor of hydraulic traits (stem
P50). Other traits contributed to drought tolerance;
terete leaf form and higher sapwood area to leaf area ratio (HV) would
be expected to reduce whole plant exposure and stress during periods of
high evaporative demand. The study is timely given the recent
devastating drought episodes experienced across the Australian
continent, and in many regions throughout the world.