Directional Selection on Tree Seedling Traits Driven by Experimental Drought Differs Between Mesic and Dry Populations

We evaluated population differences and drought-induced phenotypic selection on four seedling traits of the Australian forest tree Eucalyptus pauciflora using a glasshouse dry-down experiment. compared dry mesic populations tested for directional lamina length (reflecting leaf size), shape, node ontogenetic transition to petiolate loss vegetative juvenility), lignotuber size recovery trait). On average, had smaller broader leaves, greater retention juvenile state larger lignotubers than population, but did not differ in survival. While there was statistical support acting focal one or other between gradient estimates two traits, only trait—lamina length—exhibited pattern consistent with observed being result past adaptation reduce susceptibility acute drought. The suggests that future increases drought risk wild will shift mean toward population. Further, we provide evidence suggesting an early age trade-off damage phenotypes which develop more susceptible death. Such trade-offs could have contributed absence survival, despite marked differentiation traits.