Variation and change in behavior: a comment on Loftus et al.

Abstract

Variation and change are different but easily confused (Gordon 1991). Variation is due to differences among individuals at a point in time. A reaction norm, due to differences among genotypes in their response to a particular environmental condition, leads to variation among genotypes at a point in time (Gupta and Lewontin 1982). By contrast, change happens over time. Developmental plasticity is a trajectory over time, from changes in how individuals respond to conditions (Sultan 2015).This article puts together the idea of variation among individuals in behavior, how individuals differ at a particular point in time, and behavioral change over time in response to changing conditions. Differences among individuals in how they change over time are called a reaction norm or “behavioral type.” This represents change over time in behavior as a consequence of something else that is static and inherent, or “pre-existing,” as the authors put it.