What could lead to different populations of the same species living in different environments?

The animals' ancestors had migrated from South America to the Galápagos Islands. Descended from a common ancestor. Populations of the same species living in different places. become increasingly different as each population becomes adapted to its own environment.

Explanation:

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Migration, because species move to other places for food or a better or more suitable habitat and sometimes their is other species there.

Different ecological and biogeographical causes lead to different populations of the same species living in different environments. Ecological factors include intraspecific competition, migration, resource searching, habitat destruction, among others. Biogeographical dispersion involves wider areas and time factor. Human action is also a cause of dispersion.

Dispersion can be defined as the dissemination and distancing process of some individuals from others. It refers to the change in an organism's range or distribution area.

Different ecological and biogeographical processes might be involved in organisms' dispersion.

            → Jumping dispersion refers to a few individuals, in a short time, that  can cross a barrier and occupy a new area. In this situation, the establishment is not always for sure. They must reproduce and start a new population of a certain size that can survive the new conditions.

            → Diffusion refers to populations that, through many generations, explores and expands in new regions with favorable conditions.

            → Secular migration is the diffusion through thousands of generations.

When two populations of the same species migrate to new areas and adapt to different environmental pressures, they will probably suffer from the speciation process with time, becoming two different species.

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