Getting clear about the F-word in genomics

Abstract

Although biology is generally awash with adaptationist "just-so" stories, the situation in molecular biology and genomics is particularly bad. Various types of non-coding DNA are routinely interpreted as functional without adequate consideration of non-adaptationist alternative hypotheses Part of the problem is surely due to a failure in these disciplines to appreciate theoretical developments in population genetics, which outline the conditions under which genetic elements are selected However, as a number of authors have noted, the problem is also partly due to a confusion about the various possible meanings of "function" in biology Our central thesis is that there exists an overlooked dichotomy in the way that researchers see natural selection to be related to function. Traits or genetic elements that are merely under purifying selection have what we call maintenance functions whereas those that have historically been under directional selection have origin functions. We argue that ignoring this distinction encourages a form of pan-adaptationism, where highly plausible non-adaptive explanations for the origins of certain genetic elements or traits are themselves ignored. Thus, our recommendation is for researchers to always clarify which sense of "function" they mean (origin or maintenance) when talking or writing about selected effects.

Topics & Concepts