An Analysis of Inter-Population Divergence in Visual Display Behavior of the Green Anole Lizard (Anolis carolinensis) Natasha Bloch* & Duncan J. Irschick  * Department of Biological Science, Universidad de los Andes, Bogota, Colombia  Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA Introduction Variation in habitat use among animal populations can profoundly influence how sexual selection oper- ates on social behavior, mating systems and there- fore, visual signals (see Arnold 1983; Anderson 1994; Wade 1995; Butler et al. 2000; Baird & Sloan 2003; Baird et al. 2003; Shuster & Wade 2003; Zamudio & Sinervo 2003). Previous syntheses have outlined the complex manner in which factors such as habitat visibility, predation risk, density of conspe- cifics, food availability or temperature can affect visual displays (Fleishman 1988, 1992; Endler 1992; Ord et al. 2002; Whiting et al. 2003; Zamudio & Sinervo 2003). Habitat visibility (how far can a visual signal be detected by receivers), may have a strong impact on both the form and intensity of visual signals (Luyten & Liley 1991). Another impor- tant factor is whether the available habitat is distrib- uted continuously, or rather arrayed in discrete clumps (Goldberg et al. 2001; Zamudio & Sinervo 2003). Such different habitat arrangements can dra- matically influence the distribution of potential mates and resources (Grant 1993; Hews 1993; Baird et al. 1997; Emlen & Oring 1997; Orrell & Jenssen 2003; Zamudio & Sinervo 2003). A third factor is the relative risk of predation (Endler 1983), which can result in a trade-off between displaying to acquire mates and survival (e.g. tungara frogs, Ryan et al. 1982; Ryan 1985). Correspondence Duncan J. Irschick, Department of Ecology and Evolutionary Biology, 310 Dinwiddie Hall, Tulane University, New Orleans, LA 70118, USA. E-mail: irschick@tulane.edu Received: May 23, 2005 Initial acceptance: July 15, 2005 Final acceptance: July 15, 2005 (S. A. Foster) doi: 10.1111/j.1439-0310.2006.01162.x Abstract Variation in habitat structure can profoundly affect the evolution of vis- ual displays in animals. We compared the field display behavior of two populations of the green anole lizard (Anolis carolinensis) in Southern Louisiana. These two populations occupy habitats varying markedly in structure (clumped vs. continuous), ecological setting (urban vs. nat- ural) and the degree of male competition and predation. We filmed 56 large adult male lizards during the active spring reproductive period and detected substantial divergence in display behavior between populations. We found that (1) relative dewlap areas did not differ significantly between populations, (2) Tulane anoles spent about twice as much time displaying compared with Good Hope field anoles, although the average display duration did not differ significantly between populations, and (3) the two populations differed significantly in the relative frequency of display types: lizards from the Tulane population used a higher propor- tion of A and B display types, whereas Good Hope Field anoles used C displays more often. Finally, we detected differences in other aspects of display behavior (use of display modifiers, volley length distributions). We suggest that these display differences may result from differences in green anole male density (three times higher at Tulane), combined with habitat differences (clumped vs. continuous). Ethology Ethology 112 (2006) 370–378 ª 2006 The Authors 370 Journal compilation ª 2006 Blackwell Verlag, Berlin