Display Diversity 
273 
single, head bobbing display pattern in non- 
anoline iguanid lizards according to the 
social context in which it appeared. The dis- 
play can be performed with or without a 
conspecific present. Under the latter condi- 
tion, the display pattern shows slight head 
movement amplitude with few or no modi- 
fiers, e.g., throat lowered, body sides com- 
pressed. The species-typical display pattern 
given under these low-conflict or motiva- 
tional situations was labeled the “assertion 
display.” The same display pattern per- 
formed under high conflict or motivational 
situations, e.g», male-male confrontations, 
is produced with maximum head amplitude 
movements, i.e., via full extension of the 
legs, and is accompanied by many modifiers. 
This form of the display was called the 
“challenge display.” Bussjaeger (1971 :35- 
36) has thoroughly described the distinction 
between these two terms in his display 
analysis of sceloporine lizards. Stamps and 
Barlow (1973: 69-70) first suggested the 
term “signature bob” to indicate the stereo- 
typed head bobbing display pattern unique 
to Anolis aeneus. For species with more than 
one stereotyped display pattern, the signa- 
ture display would be defined as that display 
type performed in a context in which there is 
little or no social interaction (the “assertion” 
context). Displays within this context may be 
nondirected. In my experience, the signature 
display is used in courtship and challenge as 
well as in assertion contexts; however, dis- 
play types other than the signature display 
are not observed in the assertion context. 
characteristics : ( 1 ) degree of display stereo- 
typy, (2) degree of display complexity, and 
(3) size of display repertoire. 
Degree of Display Stereotypy 
Phenacosaurus heterodermiis, a near rela- 
tive of anoles (Etheridge, 1960) living 
in Colombia, is a good example of 
strong display stereotypy. Jenssen (1975) 
found that a male performed its signa- 
ture display (Fig. 3) with almost no 
temporary variability. The coefficient of vari- 
ation (C.V. = standard deviation ^ 
mean 
for the units which comprise the signature 
display ranged from 2.9 to 5.8 percent, and 
the C.V. for the total duration of the signa- 
ture display was 3.9 percent. Such consistent 
temporal stereotypy is relatively rare in the 
ritualized signals of animals as indicated by 
Barlow’s (in press) review of modal action 
patterns. 
In contrast to the consistent displays of 
P. heterodermus, the displays of Anolis opali- 
mis do not have a single stereotyped pattern 
(Jenssen, in press). From an analysis of 639 
displays by 51 males, no discrete pattern or 
patterns emerged for either the species or any 
one individual. The opalinus displays consist 
of four to eleven head bobs followed either by 
none or up to eight pulses of the dewlap. 
The bobs within a display are qualitatively 
similar, being produced by a simple up-and- 
down motion of the head. It is the interbob 
A SURVEY OF DISPLAY DIVERSITY 
I have found marked interspecific differ- 
ences in many features of anoline display 
behavior in the eight species I have ex- 
amined. Since the genus contains over 250 
species, more differences will doubtless be 
found as more species are systematically 
studied. 
To provide an appreciation for the breadth 
of display diversity in Anolis, contrasts be- 
tween species are provided for three display 
UNITS 12 3 4 5 6 7 8 9 II 13 15 16-20 
UJ_U_U 
I 2 3 4 5 6 7 e 9 10 II 12 
SECONDS 
Figure 3. Display-action-pattern (DAP) graph of 
the signature display from a male Phenacosaurus 
heterodermus. Upper edge of the blackened area 
represents head amplitude movement through 
time. 
