Selection for Low Calcium Tolerance in Brassica rapa
Stadel, Tyler John
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Ecosystems across a landscape can vary in their selection pressures and therefore can vary in the species that are able to survive there. Selection pressures applied on a species found in multiple ecosystems may lead to a divergence into different taxa adapted to different selective conditions. One such soil condition with strong selection pressures are serpentine soils. They are unique in that they have low levels of essential nutrients, specifically calcium, and high levels of heavy metals. To examine the effect of serpentine-like conditions on a model plant species, I grew Brassica rapa in a low calcium hydroponic environment and selected the most tolerant individuals within a population. After three generations, life history variables didn’t change in comparison to controls, except dry mass. This could indicate that this population is at the beginning of a longer term evolutionary divergence. More generations of selection are needed to confirm this idea.