Seedling response to environmental variability: The relationship between phenotypic plasticity and evolutionary history in closely related Eucalyptus species.
PREMISE OF THE STUDY
Phenotypic plasticity is an important means through which organisms cope with environmental variability. We investigated seedling plasticity in the green ash eucalypts within a phylogenetic framework to examine the relationship between plasticity and evolutionary history. The green ashes are a diverse group, which include the tallest flowering plant in the world (Eucalyptus regnans) and a rare mallee less than 1 m tall (E. cunninghamii).


METHODS
Seedlings of 12 species were exposed to high and low nutrient and water availability in a factorial experiment. Leaf trait and total plant plasticity were evaluated using the phenotypic plasticity index. A phylogeny of the species was estimated using genome-wide scans.


KEY RESULTS
We found significant differences in functional traits across species, growth forms, and substrates in response to changes in resource availability. Many traits (e.g., leaf width) were highly plastic for most species. Interspecific differences in leaf-level plasticity was significant, however plasticity was not correlated with phylogeny. Species with broader environmental niches had higher leaf-level plasticity than species with narrower environmental ranges.


CONCLUSIONS
Plastic responses to environmental variability can differ widely among closely related species, and plasticity is therefore likely to be associated with many factors, including habitat and range size, as well as evolutionary history. Our results provided insights for species delimitation in Eucalyptus, which have management implications. Because of the high number of rare species and that other species are commercially important, a more comprehensive understanding of plasticity is essential for predicting their response to changing climates.
['Rutherford|Susan|S|', 'Bonser|Stephen P|SP|', 'Wilson|Peter G|PG|', 'Rossetto|Maurizio|M|']
D005075:Biological Evolution D004777:Environment D005052:Eucalyptus D010641:Phenotype D010802:Phylogeny D018515:Plant Leaves D036226:Seedlings
nutrients Australia BayesTraits Diversity Arrays Technology (DArT) Myrtaceae climate change conservation phylogenetic relationships phylogenetic signal water treatments