Suggest a hypothesis why endotherms have independently evolved a 4-chambered heart if mixing of blood seems not to be a major issue. what else makes a 4-chambered heart preferable for sustaining the high metabolic oxygen demand of tissues in endotherms?

The image shows the evolution of a species of fish. a few fish from a population developed different social behaviors and evolved into different species. two fish according to the image, the fish underwent . the new species of fish had mating seasons that were different from that of the original fish. because of the differences in mating seasons, the fish underwent reproductive isolation. this mode of isolation would be .