A scientist observed two populations of insects for 10 years. They took data on the length, in mm , of the insect’s mouthparts. Their data is shown in the graphs below. How is this population evolving and what agent of evolution is most likely at work?
a. inbreeding, because the gene distributions are becoming less similar among the population
b. genetic drift, as the distribution of traits has become more random
c. gene flow, as the population has likely gained new mouthpart traits through immigration
d. natural selection, as insects that have mid-sized mouthparts are being favored