Your skeletal system gives the body structure and support while your muscular system helps provide movement.
Need that answer choices..
Population bottlenecks. but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted.
Crossing over. Parts of sister chromatids will sometimes switch places with the parallel part, resulting in a completely unique DNA sequence.
LOCAL ENVIRONMENT ISSUE:
People dump a lot of trash in the sea, and the sea creatures living there goes through a lot of trouble to live with all the muck getting in them. Of course, don't write it like that in your assignment - you'll get told off for the straight forwardness.
