Question: The following graph shows the results from a study looking at differences between plant genotype responses to herbivory. G1, G2 and G3 refer to three different plant genotypes (same species of plants, but samples from three genetically different individuals). On the y-axis, “gDM” stands for “gram dry matter” and is another way to express plant weight. So aphid density is expressed as number of aphids per gram of dry plant weight.

Note: if error bars (standard error of means) don’t overlap, assume significant differences. If error bars overlap, there is no significant difference)

1) State in one sentence the main finding of this study based on this graph

2) How many treatments did this experiment have?

3)  Is there a statistical interaction between the treatments? please explain why or why not

4) Aphids are phloem-feeders. How can this result be explained (focusing on the G1 and G3 genotype)

thanks