Psychobiology of Lizard Reproduction 
165 
female sexual receptivity with the follicular 
changes seen during the normal ovarian 
cycle (Crews, 19736). 
For this experiment, females of unknown 
physiological state were introduced into test 
cages containing a dominant, sexually active 
male and two subordinate, sexually inactive 
males. In behavioral tests lasting a maxi- 
mum of 1 hour, females were categorized as 
either nonreceptive or receptive depending 
upon whether they accepted the courting 
test male. 
Following the behavioral test, females 
were removed from the test cage and their 
ovarian condition determined. Ovarian con- 
dition was determined in the following man- 
ner (see Table 3) : First, depending upon the 
state of the ovarian follicles, females were 
classified as reproductively inactive, as indi- 
cated by the presence of previtellogenic 
(unyolked) follicles, or reproductively active, 
as indicated by the presence of yolking 
follicles. Reproductively active females were, 
in turn, categorized according to the size of 
the largest ovarian follicle. Finally, the re- 
productively active females were considered 
to be in their first, second, or third follicular 
cycles depending whether there were 0, 1, 
or 2 corpora lutea (CL) present, respec- 
tively. In using this procedure, therefore, 
neither the reproductive condition nor the 
sexual receptivity of the females was known 
prior to testing. 
In three different groups of females tested 
in this manner — winter-dormant females 
environmentally stimulated in either (a) all- 
female or (b) male-female groups as well 
as (c) freshly captured breeding females — 
Table 3. Criteria for determining ovarian 
condition of female Anolis caroKnensis. 
Diameter of 
Number of 
State of 
Largest Ovarian 
Corpora Lutea 
Ovarian Follicles 
Follicle (mm) 
(follicular cycle) 
Previtellogenic 
1.2-1.9 
1 <3.5 
0 (first cycle) 
Vitellogenic 
{ 3.5-6.0 
1 (second cycle) 
1 <6.0 
2 (third cycle) 
ovarian state was found to be closely corre- 
lated with sexual receptivity. None of the 
females later found to be reproductively in- 
active, as indicated by the presence of pre- 
vitellogenic follicles, was receptive to the 
courtship of the test male. Similarly, none 
of the females later found to be in their 
first follicular cycle but with small ( <3.5 mm 
in diameter) yolking follicles was receptive. 
In contrast, all of the females later found to 
have large preovulatory follicles — whether 
in their first, second, or third follicular cycles 
— were receptive to the courting males. 
Interestingly, in every group, some of the 
females later found to have medium-sized 
follicles (3.56-6.0mm) were receptive to the 
test male while others were not. This sug- 
gests that the transition from nonreceptivity 
to receptivity occurs during this phase of 
follicular development, but that the exact 
point of the switch-over varies from female 
to female. It is possible that these variations 
may be due to individual differences in neural 
sensitivity to levels of hormones secreted by 
the developing follicle. 
What do these findings contribute to our 
knowledge of the reproductive biology of 
A. carolinensis? Female A. carolinensis dis- 
play the typical anoline pattern of reproduc- 
tion (Crews, 1975c). Instead of laying a 
number of eggs in one or more clutches as 
do most temperate-zone lizards, female A. 
carolinensis lay a single egg every 10 to 14 
days for the duration of the breeding season 
(Fig. 12). This pattern of ovarian activity is 
generated by the development of ovulation 
of a single ovarian follicle alternately be- 
tween ovaries. It is logical to assume that 
this regular pattern of follicular develop- 
ment, ovulation, and oviposition during the 
breeding season also refiects corresponding 
cyclic changes in the secretion patterns of 
gonadotropic and ovarian hormones. The 
demonstration of a close correlation between 
sexual receptivity and stage of follicular 
maturation further suggests that sexual re- 
ceptivity in female A. carolinensis is depen- 
dent upon hormonal conditions which arise 
in the course of normal follicular develop- 
ment and is thus rhythmical in nature in a 
