The interplay between genetic and learned components of behavioral traits

Abstract

This article considers the evolution of behavioral traits that have both a genetic basis and can be modified. The modifications considered concern an adaptive (learnt) response to environmental influences. In theory, the evolution of such traits may lead to two extreme outcomes; one where the trait becomes genetically fixed (and phenotypically invariable) and the other where it is entirely shaped by environmental influences. Between these extremes lies a spectrum of traits containing a genetic component, but also, to differing degrees, a modifiable component. We review theory considering how learning may affect the genetic evolution of a behavioral trait (commonly referred to as the Baldwin effect). We claim behavioral interactions in tritrophic systems, such as the responses of natural enemies to herbivore-induced plant volatiles, provide an excellent model system to study the Baldwin effect and we illustrate this with recent findings on the searching behavior of the predatory mite Phytoseiulus persimilis.

How Adaptive Learning Affects Evolution: Reviewing Theory on the Baldwin Effect

“…An empirical approach requires a model system where (1) genetic variation for both a behavioral trait and the ability to learn are demonstrated, and (2) where the level of learning (Cahill et al 2001 ) and the innate value of the behavioral trait (Samuels 2004 ) can both be quantified as separate traits. Evidence is growing that the above requirements are often satisfied in ecological systems involving, e.g., parasitoids and their hosts (Wang et al 2003 ; Hoetjes et al 2011 ; Takemoto et al 2011 ) or predatory mites and their prey species (Egas and Sabelis 2001 ; Nomikou et al 2003 ; Sznajder et al 2011 ) or other species (Dukas and Bernays 2000 ; Behmer et al; 2005 ). Behavioral responses in such ecological systems provide a model to study the role of learning in evolution as well as in ecological interactions.…”