Which process is demonstrated by the similar physiological traits found in dolphins and sharks?

The process demonstrated by the similar physiological traits found in dolphins and sharks is convergent evolution. This occurs when different species, which may not share a recent common ancestor, independently evolve similar traits as they adapt to similar environments or ecological niches.

In the case of dolphins and sharks, both are adapted to living in aquatic environments, which leads to similar streamline body shapes, fins, and other adaptations suited for swimming. Despite dolphins being mammals and sharks being fish, the pressures of their environments lead to these analogous structures, reflecting how they have both evolved to overcome similar challenges in their respective habitats.

This phenomenon is distinguished from divergent evolution, where related species evolve different traits, often due to different environmental pressures. Natural selection is the mechanism driving evolution but does not specifically refer to the similarity seen across unrelated species; instead, it is the process by which traits become more common in a population based on their advantageousness. Genetic drift involves random changes in trait frequencies in a population and does not explain the development of similar traits in unrelated species.