Convergent evolution

Definition

Independent evolution of similar traits or structures in distantly related lineages that lack those features in their last common ancestor; produces analogous (homoplastic) characters rather than homologous ones. In arthropods, convergent evolution is common in morphology (e.g., elongate body forms in centipedes and certain insect larvae), physiology (desiccation resistance in unrelated desert arthropods), and behavior (web-building in spiders and some insect larvae).

Etymology

From Latin convergere (to incline together) + evolutio (unrolling, development); in evolutionary biology since early 20th century.

Example

Striking case: the camera-type eyes of cephalopod mollusks and vertebrates evolved independently, but among arthropods, the compound eyes of insects and the compound eyes of crustaceans are homologous—whereas the simple eyes of some spiders and the stemmata of holometabolous insect larvae represent convergent solutions to low-light vision despite different developmental origins.

Synonyms

• homoplasy (cladistic usage)

Related Terms

• analogous structure
• Homology
• Parallel evolution
• adaptive radiation
• mimicry
• cryptic species

Usage Notes

Distinguish from parallel evolution, where similar traits arise in related lineages with comparable genetic and developmental backgrounds. Homoplasy is the cladistic term for the pattern, regardless of mechanism; convergence implies adaptation to similar selection pressures. Careful usage reserves 'convergent' for distantly related taxa, though the boundary is debated. In systematics, convergent characters mislead phylogenetic reconstruction if mistaken for homologies.