Malaria, which kills more than a million people each year worldwide, is caused by a Plasmodium that spreads between hosts by infected mosquitoes. The more people bitten by each infected mosquito, the higher the transmission rates of malaria. Does infection by Plasmodium cause a mosquito to bite more people? To test this, researchers captured 262 mosquitoes that had human blood in their guts (Koella et al. 1998). They measured two attributes: whether mosquitoes were infected with malaria, and whether they had fed on the blood of more than one person (assessed by DNA fingerprinting of blood in mosquito guts). Of 173 uninfected mosquitoes, 16 had taken multiple blood meals. Of 89 infected mosquitoes, 20 had fed multiple times.

a. Illustrate these results with a graph. What association is suggested?

b. Do these data support the idea that infected mosquitoes behave differently than uninfected mosquitoes?