What defines convergent evolution?

Convergent evolution is characterized by completely unrelated species developing similar traits as a result of adapting to similar environments or ecological niches. This phenomenon occurs when different species face comparable environmental challenges, leading them to evolve similar solutions, despite not sharing a recent common ancestor. The classic examples of convergent evolution include the wings of bats and birds, which serve the same function for flight but evolved independently in these different lineages.

The other options do not accurately describe convergent evolution. While the first option refers to divergent evolution, where similar species arise from a shared ancestor, the third option speaks to the evolution of a common trait in distinct species but doesn’t emphasize the unrelated nature of those species. The last option describes a scenario where one species evolves into multiple forms, which is indicative of adaptive radiation rather than convergent evolution. Therefore, the defining characteristic of convergent evolution is indeed the occurrence of independent species becoming more alike due to similar environmental pressures.