Geographic range size, seedling ecophysiology and phenotypic plasticity in Australian Acacia species

Pohlman, Catherine L., Nicotra, Adrienne B., and Murray, Brad R. (2005) Geographic range size, seedling ecophysiology and phenotypic plasticity in Australian Acacia species. Journal of Biogeography, 32 (2). pp. 341-351.

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Aim: The degree to which eco-physiological traits critical to seedling establishment are related to differences in geographic range size among species is not well understood. Here, we first tested the idea that seedling eco-physiological attributes associated with establishment differ between narrowly distributed and geographically widespread plant species. Secondly, we tested the notion that species occupying wide geographic ranges have greater phenotypic plasticity in response to the environment than contrasted species with more restricted distributions.

Location: Eastern Australia.

Methods: We compared five pairs of geographically restricted and widespread Acacia species grown under glasshouse conditions for differences in seedling relative growth rate and associated allocational, morphological and physiological traits. We then examined whether widespread species displayed greater phenotypic plasticity in these traits than narrowly distributed species in response to changes in soil water availability.

Results: Neither relative growth rate nor any measure of biomass accumulation or allocation differed significantly between seedlings of narrowly distributed and widespread species. In addition, the plasticity of biomass allocation was not greater in widespread species. However, the leaflets of widespread species had higher photosynthetic capacity and greater plasticity of water use efficiency than the leaflets of narrowly distributed species.

Main conclusions: We demonstrated fundamental differences in the physiology and plasticity of leaflets of widespread and narrowly distributed species. The greater plasticity of these seedling leaflet traits may allow widespread Acacia species to utilize a wider range of environmental conditions in relation to soil moisture than restricted Acacia species. However, we did not find corresponding differences in mean or plasticity of seedling growth and allocational traits. In general, we suggest that relationships between rarity and species traits are both context and taxon specific.

Item ID: 4712
Item Type: Article (Research - C1)
ISSN: 1365-2699
Keywords: Acacia, Australia, phenotypic plasticity, range size, relative growth rate, seedling, specific leaf area, water availability
Date Deposited: 06 Jul 2009 06:41
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060203 Ecological Physiology @ 30%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060302 Biogeography and Phylogeography @ 35%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060303 Biological Adaptation @ 35%
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