Evolutionary ecology of phosphorus use in Daphnia

 

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         Much of the work on global environmental change has been about how ecosystem-level changes are impacted by anthropogenic pollutants. Comparatively little is known about the evolutionary changes that happen in populations inhabiting such damaged ecosystems. My research seeks to gain a predictive understanding of evolutionary responses to altered environmental factors. Human activity has profoundly altered ecosystems; a notable example is the dramatic effect application of phosphorus (P)-rich fertilizers has on lake ecosystems. The excessive addition of these nutrients in water bodies, due to runoff, causes rapid growth of algae and ultimately animal death from a lack of oxygen, in a process called eutrophication. Resurrecting diapausing (resting) eggs of the aquatic keystone herbivore, Daphnia, preserved in lake sediments for centuries has revealed striking shifts in nutrient use physiology that are correlated with nutrient enrichment (i.e., cultural eutrophication). As such, this system allows us to address key issues in ecological genomics with a unique temporal approach that is not possible with more common space-for-time substitutions (i.e., comparing populations to infer evolutionary trajectories). Understanding such responses is particularly important with regards to current global changes such as eutrophication driven by alteration of a single element (e.g. phosphorus), furthering our understanding evolutionary responses to environmental change, and more generally about the fundamental factors underlying growth and productivity.