Question

How would a biologist explain the evolution of the adaptations (enlarged heart and lungs and massive upper legs that enable rapid leg movements) enabling the great speed of pronghorn assuming their ancestors did not possess these phenotypic traits?

Answer 1

The great speed of the proghorns can be explained by the Theory of Lamarck of the Inheritence of Acquired Characters. The proghorn ancestors did not possess the ability of great speed initially. But Lamarck's inheritence theory suggests that an organism when undergoes changes in order to adapt to it's environment, the character traits are passed on to the next generations. Just like in case of the giraffes that he said grew longer necks to eat off leaves from tall trees. The proghorns live in mountainous arease where there are numerous natural and predatorial threats. Running away from predators, finding food, moving in clusters etc can all account for the great speed adaptation by the proghorns. With change in the adaptations, the change came in their phenotypic characters and thus were passed on to the nex generations. The anciet threats to the ancestral proghorns have led to the development of the characters in the recent generations for years.