| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 922.64 KB | Adobe PDF |
Advisor(s)
Abstract(s)
Selection on plant functional traits may occur through their direct effects on
fitness (or a fitness component), or may be mediated by attributes of plant
performance which have a direct impact on fitness. Understanding this link is
particularly challenging for long-lived organisms, such as forest trees, where
lifetime fitness assessments are rarely achievable, and performance features
and fitness components are usually quantified from early-life history stages.
Accordingly, we studied a cohort of trees from multiple populations of
Eucalyptus pauciflora grown in a common-garden field trial established at
the hot and dry end of the species distribution on the island of Tasmania,
Australia. We related the within-population variation in leaf economic (leaf
thickness, leaf area and leaf density) and hydraulic (stomatal density, stomatal
length and vein density) traits, measured from two-year-old plants, to two-year
growth performance (height and stem diameter) and to a fitness component
(seven-year survival). When performance-trait relationships were modelled for
all traits simultaneously, statistical support for direct effects on growth
performance was only observed for leaf thickness and leaf density.
Performance-based estimators of directional selection indicated that
individuals with reduced leaf thickness and increased leaf density were
favoured. Survival-performance relationships were consistent with size-
dependent mortality, with fitness-based selection gradients estimated for
performance measures providing evidence for directional selection favouring
individuals with faster growth. There was no statistical support for an effect
associated with the fitness-based quadratic selection gradient estimated for
growth performance. Conditional on a performance measure, fitness-based
directional selection gradients estimated for the leaf traits did not provide
statistical support for direct effects of the focal traits on tree survival. This
suggested that, under the environmental conditions of the trial site and time
period covered in the current study, early-stage selection on the studied leaf
traits may be mediated by their effects on growth performance, which in turn has a positive direct influence on later-age survival. We discuss the potential
mechanistic basis of the direct effects of the focal leaf traits on tree growth, and
the relevance of a putative causal pathway of trait effects on fitness through
mediation by growth performance in the studied hot and dry environment
Description
Keywords
directional selection selection gradients leaf thickness and leaf density leaf area stomatal density and stomatal length vein density growth performance tree survival
Pedagogical Context
Citation
Costa e Silva J, Potts BM, Wiehl G and Prober SM (2022) Linking leaf economic and hydraulic traits with early-age growth performance and survival of Eucalyptus pauciflora. Front. Plant Sci. 13:973087
Publisher
Frontiers