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Abstract Detail


Choe, Gina [1], Whitton, J [2].

Differentiation in morphology and response to salinity between populations of the Lasthenia californica complex (Asteraceae).

Populations of Lasthenia californica show high habitat and phenotypic variability. Observations in the field suggest that phenotypic variation tracks environmental gradients. Populations that inhabit salty habitats such as saline pools or coastal areas can be stunted or large and creeping, succulent and high in sodium content. Populations in ionically benign inland sites tend to be more uniform in phenotype, and are typically low in Na content and lack succulent leaves. Our objective was to study the relative contributions of genetic differentiation and phenotypic plasticity to the observed differences in morphology and physiology. To investigate the basis of this trait variation within Lasthenia californica we tested 4 populations, 2 from inland and 2 from coastal sea spray exposed sites in a common garden with varying levels of salt. We recorded both leaf morphology traits (succulence, specific leaf area, leaf number) and aspects of ion physiology (cation accumulation). In addition, we recorded indicators of overall growth: relative growth rate and final biomass. Results suggest that populations from the coast were less hindered by increasing salinity, as biomass was significantly less affected between salt treatments and controls. The data also suggest that morphological differentiation is mostly genetically determined. Leaf traits differed significantly between populations, where individuals across treatments were similar to their field-collected parents. Ion physiology traits tended to show the greatest plasticity. Individuals across populations had similar ion accumulation patterns in the control, but populations then diverged in patterns of Na accumulation as sodium treatments increased, resulting in a significant population by salt level interaction. Increased Na accumulation and succulence were associated with higher biomass under saline conditions, following predictions made from field data. In conclusion, it appears that for most of the traits examined, genetic differentiation is a key determinant of the response to environmental variation.


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1 - University of British Columbia, Botany, 3529-6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
2 - University of British Columbia, Botany Department, 3529-6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada

Keywords:
Lasthenia californica
differentiation
salt
succulence
ion accumulation
adaptation
leaf traits.

Presentation Type: Array
Session: TBA
Location: Williford B/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:30 AM
Number: 003
Abstract ID:1207


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