What are three benefits and risks associated with genetically engineered animals?

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.

Which of these is not an obstical to the future of space exploration? fundingresearch ideas technologytime

Which of the following are causes of evolutionary change? 1)genetic drift 2) natural selection 3) gene flow 4)mutation