Which animal trait was Darwin’s theory on natural selection based on

Answer 1

Darwin's theory of natural selection was based on the observation that within any population of organisms, variations exist. Some of these variations are heritable and can give individuals a reproductive advantage in their environment. Over time, these advantageous traits will become more prevalent in a population as they are passed down through generations, while less advantageous traits will decrease. This process of natural selection is the driving force behind evolutionary change and adaptation in species.