What does parallel evolution refer to?

Parallel evolution refers to the process where two or more species that share a close evolutionary ancestor evolve similar traits or characteristics independently, often as a response to similar environmental pressures or challenges. This process illustrates how related species can face similar selective pressures and converge on similar adaptations, despite being separated by time or geographical barriers.

In this context, divergent evolution (mentioned in the second option) implies that although the species originate from a common ancestor, they undergo changes that lead to different forms. This is relevant to parallel evolution because it highlights the shared ancestry of the species involved; they have diverged from a common lineage but still exhibit similar adaptations.

The other options do not accurately describe parallel evolution. For example, the first choice suggests completely different forms, which is characteristic of divergent evolution rather than parallel evolution. The third option discusses competitive adaptations, which may involve mimicking traits but does not specifically address the shared ancestry aspect of parallel evolution. The fourth option refers to evolution driven by environmental changes, which can lead to various forms of evolution, but it does not precisely define parallel evolution as it lacks the component of shared ancestry.