A scientist believes that bright red chest coloring on male birds makes them more attractive to females. In an experiment, she uses six birds, all with the same color chest. She bleaches the feathers of two of the birds, dyes the chests of two of the birds bright red, and leaves the chests of two of the birds alone. When females are exposed to these males, she believes that more females will chose to mate with the red-dyed males. What are the independent and dependent variables in this experiment?