Patterns and Analysis of Adaptive Phenotypic Plasticity in Animals

Abstract

Abstract The most obvious ecological difference between animals and plants is that most animals move through space in response to changing conditions whereas plants do not. The evolution of a complex neuromuscular system that enables animals to receive, process, and respond to information with coordinated movement through space is perhaps the most impressive feat of adaptive phenotypic plasticity, broadly defined. However, this ability to move through space cannot resolve all environmental challenges. There will therefore be selection for adaptive phenotypic plasticity in morphology, physiology, behavior, and life history characters in response to the many diverse and risky situations animals face. Two main questions of interest to evolutionary biologists investigating this topic are ( l) what kinds of environmental variation select for adaptive plasticity, versus other evolutionary responses such as local adaptation or polymorphism, and (2) what constrains the evolution of plastic responses? Empirical evaluation of adaptive plasticity in animals over the past two decades has revealed a wide diversity of solutions to an equally wide array of environmental problems (Scheiner 1993; Travis 1994; Gotthard and Nylin 1995; Skulason and Smith 1995; Via et al. 1995; Roff 1996; Nylini and Gotthard 1998; Schlichting and Pigliucci 1998; Tollriani and Harvell 1999; chapter l 0). In many areas, theoretical explorations have far outpaced empirical testing (Via et al. 1995; Agrawal 2001; chapter 6). For example, testing some of the more recent models will require information on the spatial and temporal distribution of alternative environments, whether they are population sources or sinks, and movement among patches (e.g., Houston and McNamara 1992; Siblyl995; Whitlock 1996; Sasaki and de Jong 1999). This imbalance between conjecture and data will probably persist because rigorously testing plastic adaptations can be timeconsuming and logistically difficult.