Roche, Bernadette , Leumas, Elizabeth , Veatch-Blohm, Maren .
The Effects of Different Calcium to Magnesium Ratios on Calciferous and Serpentine Populations of Arabdopsis lyrata.
Arabdopsis lyrata is a small flowering plant found in many different environments. One striking feature of A. lyrata is its ability to grow in both calcium-rich and calcium-deficient environments, including serpentine environments. A key feature of serpentine soils is the low calcium to magnesium ratio, usually very toxic to plants. For this experiment two populations of A. lyrata were sampled: one in sandy limestone (Ca:Mg 25:1); the other in serpentine (Ca:Mg 1:3). We treated plants with solutions containing different ratios of calcium to magnesium (10:1, 1:0.1, 1:1, 0.1:1, and 1:10), two of which were close to the ratios found in limestone and serpentine habitats. We expected to find local adaptation, as evidenced by home site advantage. In particular, we expected calciferous plants to perform better in treatments with higher Ca:Mg, and serpentine plants to perform better in lower Ca:Mg. Performance was measured as shoot biomass, leaf production rate, relative water content, and chlorophyll a and b. We also measured concentrations of calcium and magnesium, and ratio of calcium to magnesium, in tissues. We found significant effects of Ca:Mg treatment on biomass, leaf production, chlorophyll a and b, and tissue concentrations of calcium and magnesium. Both treatment and population were significant for the ratio of calcium to magnesium in tissues. We found no evidence of a home site advantage under these particular calcium to magnesium ratios. We are currently repeating the experiment, with the inclusion of a new population in sandy soil (Ca:Mg 2:1). Adaptation to high magnesium may involve similar mechanisms to adaptation to high calcium, which could explain the lack of significant differences between our calciferous and serpentine populations in the Ca:Mg treatments. If this is the case, we predict that the population from the 2:1 Ca:Mg soil will underperform the other two populations in ratios containing high magnesium.
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1 - Loyola College in Maryland, Biology, 4501 N. Charles Street, Baltimore, MD, 21210, U.S.A.
calcium to magnesium ratio.
Presentation Type: Poster:Posters for Topics
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM