Phylogenetic Perspectives on the Evolution of Lizard Territoriality

The evolution of ecological and behavioral traits is difficult to study because of the absence of such traits from the fossi~ record. For example, variation in lizard territoriality both within and among species may be due to differences in Hfe-history patterns, availability of ecological resources, access to mates, or-ontogenetic and phylog~netic c;onstraints. Many studies at the intraspe-cific level have attempted to uncover reasons for differences among individuals , between the sexes, and across populations in territorial behavior using correlational analysis, experimental manipulations, and theoretical consider-However, patterns of natural and sexual selection found within extant species may not be the same as those that have been operating through evolutionary time, and the hypotheses resulting from intraspecific ecological studies cannot easily be confirmed through reference to the fossil record. At the interspecific level, studies of territoriality have been limited primarily to considerations of the importance of factors such as sexual dimorphism, foraging mode, and taxonomic status in the evolution of territorial behavior , without any statistical means of taking phylogenetic information into account (e.g., see references above). In recent years, however, the development of new comparative analysis techniques and modem phylogenies make it possible to infer the patterns and processes of ecology and behavior in ways that were previously impossible. Here, I illustrate the use of such techniques to study the (1) eyolutionary origins, (2) adaptive function, and (3) evolutionary processes underlying lizard territorial behavior. This paper is not intended to serve as a review of the available literature on lizard territorial behavior {several important papers have not been included), and the results of the analyses included herein are decided.iy preliminary due to several limitations of the data and techniques that are described in greater detail below. Rather, the main goal of this paper is to illustrate ·the use of phylogenetic comparative techniques to a specific question in the evolution of lizard behavioral ecology, and to generate new hypotheses about the evolution of territoriality that lend insight .into fruitful areas for future research at both intra-and interspecific levels.