The skeletal diagram below shows variations that were present in their common ancestor. using the diagram determine what most likely caused the variation in forelimbs? a changes in the genetic code b changes in muscle structure c development of vestigial structures d trait formation due to behaviors

D. trait formation due to behaviors

Explanation:

It is obvious to see that the three animals, cat, whale, and bat, have the same basic structure of their forelimbs, but also that they have developed differently and have taken a new shape. The reason for this is a trait formation due to behavior. The cats ancestors were terrestrial, and the cats have remained terrestrial, walking on their four legs, and having the same shape and function as their ancestors. The whales had similar forelimbs, but their ancestors started to move more and more in water. As they did, they needed more muscle power, but also greater width of the forelimb so that they can move more easily and more efficiently in the water. This behavior has gradually resulted in a flat, strong, peddle like forelimb. The bat too had similar forelimbs to that of the cat, but its ancestors started to try to fly. The process was gradual, and it started with jumping, then longer jumps, development of skin between the fingers, elongation of the fingers, thus provide more area for development of wider skin area. This has resulted in developing a light, wide, skin dominated forelimb with elongated fingers, providing flight for the bat.