1) Explain the first sentence of the abstract: “Genetic variation for partner quality in mutualisms is an evolutionary paradox.” What is this paradox?
2) Why do authors say, “It is important to note that we used allopatric populations of plants, rhizobia, and nematodes for this study.” in their methods?
3) Authors state that “Nematodes and rhizobia were inoculated onto plants simultaneously to avoid priority effects associated with different arrival times.” Explain what is meant by ‘priority effect’.
4) Explain what a point in Fig. 3A represents. Explain what a point in Fig. 3B represents. Explain the difference.
5) In Fig. 4D, how many blue points or brown points should there be? And what does it mean for there to be a “significant treatment × genotype interaction for nodule number”? Explain in terms of the lines connecting the blue and brown dots.
6) Explain what the authors consider the genetic trade-off in this study. Give two possible ways this trade-off might be manifesting itself in the legume (hypotheses explained in Discussion).