Which best describes darwin’s studies that led to the theory of evolution?
a) extensive research of an individual organism within a short period
b) extensive research of an individual organism over many years
c) observations and data collected within a short period
d) observations and data collected over many years

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.