多态性的不同命运

Lizards maintain or lose color variation through interactions between genetics, selection, and plasticity Siddharth S. Gopalan and Todd A. Castoe U nderstanding why polymorphic traits—color, shape, or be- havior differences across individuals—persist within a spe- cies is a long-standing challenge. Such variation is expected to disappear as selection favors a single optimal form. Yet despite this expectation, polymorphism occurs frequently across the tree of life. Geneticist Theodosius Dobzhansky argued that diversity could be actively maintained through “balancing selection,” which prevents genetic variants from becoming dominant or being lost (1). Early empirical studies did not clearly support this model (2–4), but evidence for balancing selection has since accumulated (5). …