ROBERT ae (MCZ) demonstrated that in both sexes of the giant anole 
of Jamaica, A. garmani, reproductive success (as measured by the number of 
ecpulatione) ‘n positively with increasing adult size, but much more 
strongly in males than in females, Female territoriality and male -male 
competition for territories containing females could also be demonstrated 
and together provide an explanation for the differences within and between 
the sexes in the relation of size to reproductive success, Associated with 
this social structure is strong sexual dimorphism in adult size and in 
growth rates. 
Trivers generalized from these observations to the hypothesis that 
female distribution controls male-male competition which, in turn, controls 
adult sexual dimorphism in size, This generalization could then be tested 
on species markedly less sex-dimorphic in size. 
On Jamaica Anolis valencienni is the species that shows least sex 
dimorphism in size. ze. Trivers had already studied this species sufficiently 
to know that its social structure was strikingly unlike that of A. garmani. 
In the summer of 1973 he and Robert Hicks endeavored to get quantitative 
data for A. valencienni which would be as comparable as possible with that 
available for A. garmani. Three kinds of data were gathered. 
1. Copulation data, Because valencienni does not mate preferentially 
on open conspicuous perches as does garmani, collection of data on 
valencienni copulations was more difficult than had been true for garmani 
and the problem of sighting biases seems more severe, However, the 
following conclusions seem permitted: size is less important for reproductive 
success for male valencienni than it is for male garmani and in fact in 
valencienni size is no more important for reproductive success in males than 
in females, Unlike garmani, adult female valencienni copulate with more 
than one male on the same day and (in the absence of interruption) with the 
same individual on successive days, Females were seen rejecting males, 
and one apparent case of "rape" was observed, Both these phenomena vere 
unobserved in garmani, 
2. Male and female home ranges, Females overlap extensively in their 
wanderings and have never been seen to display aggressiveness toward one 
another. Male home ranges overlap less than those of females but considerably 
more than those of adult male garmani, 
3. Male aggressiveness. It is established for the first time that male 
home range overlap in valencienni is accompanied by aggressiveness. Males 
display before and after fighting and fight by jaw-locking. The outcome of 
such fights is less dramatic than in garmani (or lineatopus, grahami or 
sagrei): the apparent loser turns dark and retreats slowly. He is rarely 
routed from the territory and may copulate within the defended home range 
(territory) of the adversary on the day of the fight. 
