Convergent evolution is driven mainly by:
Convergent evolution occurs when unrelated lineages independently evolve similar traits due to similar environmental pressures, such as wings in birds and bats or streamlined bodies in dolphins and sharks, resulting in analogous structures with similar function but different ancestry. It reflects adaptation to common niche, not common descent, and can mislead phylogeny as homoplasy. Divergent evolution produces homologous structures. Hence Similar selection pressures results from convergence producing analogy. This concept integrates genetics, ecology and molecular evidence, frequently tested in NEET, GATE and CSIR-NET, highlighting links between genotype, phenotype and environment.
Ref: Futuyma, Evolution, Chapter 2: Homology, Convergence, Coevolution.