Question

It takes energy and resources for a stickleback to develop spines. Thus, over time pelvic spines would not be retained in stickleback populations unless they provide some kind of selective advantage. Using this knowledge, would you agree with the following statement: "In Bear Paw Lake having pelvic spines does not seem to provide the same selective advantage as it does to stickleback living in the ocean."
(a) Agree
(b) Disagree

Answer 1

(a) Agree

It is probable that less sticklebacks will have pelvic spines in Bear Paw Lake, as it is a smaller region without as much competition. Predators may be much lower in such an environment, eliminating a need for such protection. In the ocean, however, there is much biodiversity and competition, so the fish need pelvic spines to protect themselves.