Answer:
Extrinsic regulatory mechanisms are external and depend on the firing of some factor outside the population itself. Among them are interspecific competition, food and space restrictions, very strong climatic variations, weathering and inharmonious relationships with other populations (parasitism and predatism).
Good examples of interspecific competition appear when rabbits, caves, rats compete for the same plant, or different fish and birds, such as the heron, vie for the same species of smaller fish. This is because these different species keep their populations in the same ecological niche. Competition is often so strong that some species eventually, as one example of an extrinsic homeostatic mechanism overriding an intrinsic homeostatic process is their disappearance or migration to other regions.
In this competition, the presence of adaptations among individuals in the population that promote better food search, speed, vision, and others can make the difference between elimination and survival.
4. DNA sequence comparison
5. Random mutations
The answer is Physical Property
Photosynthesis.. hope I helped (:
