If there is NO VARIATION in shell thickness within a population of snails, and no mutations occur, what happens to shell thickne
ss in response to crab predation? (Hint: Recall your experiment in the second exercise, when you turned variation off.)a. Shell thickness does not evolve in the population. b. Shell thickness evolves for some snails in the population. c. Shell thickness increases for all snails in the population. d. Average shell thickness in the population evolves over several generations
The correct answer is a. Shell thickness does not evolve in the population.
Explanation:
Genetic variation is very important for the evolution of a population. If there is no genetic variation in the population then the population or species will not evolve according to the changing environment and then their chances to become extinct will increase.
Variation can occur by mutation in gene so if there is no variation in shell thickness in a snail population and no mutation occurs then the thickness of the shell in the snail population will not evolve and crabs will easily get their food by breaking snail's shell. So the correct answer is a.
In some ways, monotremes are very primitive for mammals because, like reptiles and birds, they lay eggs rather than having live birth. In a number of other respects, monotremes are rather derived, having highly modified snouts or beaks, and modern adult monotremes have no teeth.
