These data are from Crutsinger et al. (2006) in the journal Science. In this study the researchers asked the question, does higher INTRAspecific diversity (# of unique genotypes within a species) within a plant population affect other levels of biological diversity and ecosystem processes. By manipulating the number of tall goldenrod (Solidago altissima) genotypes in experimental plots, the researchers were able to measure diversity at other levels including arthropod herbivores and predators. The researchers also measured rates of above-ground primary productivity — an important ecosystem process. In the above graphs the number of plant genotypes is represented on the x-axis (the independent variable). Three different response/dependent variables are represented on each of the y-axes. Graph (a) shows predator richness (the # of species in a given area), graph (b) shows herbivore richness, and graph (c) shows rates of above-ground net primary productivity. All three graphs shows a positive relationship to increases in goldenrod genetic diversity. These graphs suggest that increases in genetic diversity within a population can influence higher levels of biodiversity and rates of an important ecosystem process.
Questions for Discussion:
1.What is above-ground net primary productivity? Why is it an important metric of ecosystem functioning and what does it mean about the energy available for other organisms?
2.What is the difference between diversity, richness, and evenness?
3.How does increases in genetic diversity lower the probability of species extinction?
4.How might the above study help inform restoration projects?
5.If greater diversity promotes ecosystem productivity and stability then what could these data and results potentially say about the effects of human diversity on human communities?