Geographic Variations on Methodological Themes in Comparative Ethology: A Natricine Snake Perspective

The most distinctive and characteristic emphasis of early ethology was also what set it off from other post-Darwinian studies of animal behavior. This was the view that behavior varied among species in the same way as did morphological characters and that behavioral differences were as much a product of the evolutionary drama as were the characters that could be measured in museum collections (Tinbergen 1960, Lorenz 1981, Burghardt 1985, Burghardt and Gittleman 1990, Gittleman and Decker 1994). The logical extensions of this view were that behavioral phenotypes could be used in reconstructing phylogenetic histories, that the evolution of behavioral phenotypes could be studied in the same way as the evolution of other classes of traits, and that many of the behavioral differences among taxa reflected underlying genetic differentiation at both the species (Hinde and Tinbergen 1958) and population (Foster and Cameron 1996) levels. Behavior may also initiate evolutionary changes in other attributes of organisms (Mayr 1960, 1965, Wcislo 1989, Gittleman et al. 1996). Although the role of genes in behavioral determination remained controversial for years (see Gottlieb 1992, de Queiroz and Wimberger 1993 for current critiques), many behavior patterns have proven heritable (Mousseau and Roff 1987; papers in Boake 1994b). Indeed, some complex, “species-typical” behavior patterns are performed normally without opportunity for learning (Lorenz 1965). Such behavior patterns can be expressed early or late in development (Lorenz, 1981). At the other extreme, many complex behavioral phenotypes are learned with only slight, if any, genetically based predisposition to perform particular behavior patterns. Between these extremes is a diversity of interactions between genes and environment, including imprinting and complex developmental trajectories produced by interactions between neural development and experience. Many of the currently interesting and controversial questions in the nature–nurture debate do not center around species-typical behavior patterns. Instead, they concern the nature of genetic differences among individuals and populations in the performance of particular behavior patterns and in the ability to modify their performance with experience. Thus the problem must be conceptualized as one in which the interactions of specific genetic constitutions with specific environmental contexts need to be evaluated.