An evolutionary process in which related populations or species accumulate differences from a common ancestor over time, producing increasing dissimilarity in traits, genetics, or ecology.

Principle

Following a split (e.g., population subdivision or speciation), differing selective pressures, genetic drift, mutation accumulation, or distinct ecological opportunities drive descendant lineages along separate trajectories, increasing phenotypic and genetic divergence.

Demonstration

Darwin's finches illustrate divergence: descendant populations derived from a common ancestor evolved different beak shapes and sizes adapted to distinct food sources on different islands.

Misapplication

Attributing all observed differences between taxa to divergent selection when neutral processes (drift, bottlenecks) or plasticity explain patterns; conflating divergence with mere variation within a population.

Consequence

Divergence underlies speciation, niche differentiation, and the production of biodiversity; it generates diagnostic characters used in taxonomy and phylogenetics when correctly interpreted.

Reversal

Convergent evolution — unrelated lineages independently acquire similar traits, decreasing dissimilarity in particular features despite different ancestries.

Boundary

Refers to changes accruing in related lineages after common ancestry; excludes similarity arising by convergence or horizontal transfer. Temporal scale matters: short-term phenotypic plasticity is not divergence unless genetically fixed or persistent.

Semantic Tension

Tension with 'differentiation' and 'adaptive radiation' terminology; also with claims that divergence implies adaptive cause when nonadaptive processes may dominate.

Synthesis

Divergent evolution describes the process by which related lineages become increasingly different due to distinct evolutionary forces; recognizing divergence explains lineage diversification and the origin of novel traits but requires careful inference about causes and timescales.