NO- 3595 ANOLIS LINEATOPUS — RAND 63 



The same sort of informatiou suggests that relative size is also 

 important, but here an additional Une of evidence is available. In 

 the aggressive displays of these lizards, there are many elements that 

 act to increase the apparent size of the hzard (see p. 41). These 

 elements are developed most highly in adult males but some of the 

 elements, like lateral orientation and flattening, occur in all sizes and 

 in both sexes. 



That selection has favored the incorporation of so many devices 

 for increasing the apparent size of A. lineatopus into its aggressive 

 displays suggests that it is to the advantage of a hzard not only 

 to be bigger but also to appear bigger. This can only be important 

 if the reaction of an anole to an opponent is based in part on an 

 estimate of its size. (In other words, this sort of display can be 

 important only if apparent size is used by^the lizard to "predict" 

 the outcome of the dispute.) Barlow (1963) has shown experimentally 

 that certain fish discriminate between fish of their own size and of 

 those 10 percent larger or smaller. Anoles can probably do at least 

 as weU. 



In this discussion I have attempted to show that the outcomes of a 

 high percentage of disputes in A. lineatopus are predictable on the 

 basis of the relative size of the lizard and on the place of occurrence 

 and that these two factors also influence the nature of a dispute and 

 the conditions under which it occurs. Further, I have attempted 

 to show that the lizards themselves behave as if they were predicting 

 outcomes and were using the same two factors in doing so. 



Adaptive Significance of Spatial Distribution 



By "adaptive significance" of the spatial distribution of individual 

 A. lineatopus in small areas I mean the possible selective advantages 

 that this distribution can have for individual A. lineatopus and for 

 the population as a whole. This is equivalent to "function of terri- 

 tory." C. E. Carpenter (1958) and Hinde (1956) have provided 

 extensive lists of the functions of territory in various species of verte- 

 brates. Some of these functions are clearly not applicable because 

 they are related to parental care. The other functions, as Tinbergen 

 (1957) has pointed out, must be divided into those that arise from 

 the fact that individuals have definite activity ranges and those that 

 arise from the distribution of these activity ranges in relation to 

 one another. 



One adaptive advantage of an activity range is that the individual 

 can learn thoroughly the structure of the area. Anolis lineatopus 

 frequently uses indirect pathways: an anole on a branch may run 

 back up the branch and down the trunk to reach the ground, foUowing 

 a pathway that initiaUy may take it away from its objective. The 



