In a breed of dogs, there are two alleles for fur color, "B" and "b.* When a dog is "BB"
or "Bb", the dog has black fur. When the dog is "b", the dog has white fur. Which best
describes the number of genotypes and phenotypes that exist in this breed of dogs?

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.