The snails from the two environments differ because one or both has evolved by natural selection.
Explanation:
Natural selection is one of the main mechanisms that produce the evolution of species. This is because it allows the most adapted individuals in an environment to survive and pass on this characteristic that allowed them to survive their descendants. The less adapted individuals end up not resisting the difficulties of the environment and die, with that, the species begins to evolve, because only the adapted individuals are able to reproduce more adapted individuals.
If a species of snail had its population divided by a natural barrier and each half of the population was in a different environment, natural selection will be in charge of promoting an evolution in both species or just one, in relation to the adaptability of individuals with the environment.
