284 
Jenssen 
Social Function of the Display Type 
When confronting syntopic congeners, 
shared signals for interspecific communica- 
tion would be advantageous. Therefore, it 
seems reasonable that some modifiers and 
other elements of agonistic displays appear- 
ing interspecifically might be phylogenetic- 
ally more conservative than signals involved 
in social encounters requiring species’ recog- 
nition. 
Male display types functioning in court- 
ship would require a pattern for species 
recognition which contains strong, stereo- 
typed elements unique to the species or popu- 
lation. The same requirement for species 
recognition would also be found in displays 
used for declaring territorial occupancy to 
conspecifics. 
Some anoles use more than one display 
type during extended intraspecific aggressive 
encounters. These display types probably 
evolved from a single ancestral display pat- 
tern (e.g., a signature display pattern). By 
altering or adding elements to this pattern, 
a more extensive repertoire evolved. For 
species with extensive agonistic display rep- 
ertoires, it would be expected that each dis- 
play type would not be completely different 
from the others ; a display type would share 
many permanent display elements with one 
or more of the other display types. 
Based on observations of naturally occur- 
ring aggressive encounters of anoles, I would 
expect species with multiple agonistic display 
repertoires to perform these displays in a 
progressive fashion. Each successive display 
type would be more elaborate in the ritual- 
ized interaction than the previous type, ex- 
cept for that display type performed in clos- 
est proximity to the antagonist (within bit- 
ing distance). This short-distance display 
would be the least elaborate type within the 
agonistic repertoire, being of brief duration, 
having little or no dewlap extension, and 
involving postures ready to receive or deliver 
an attack. In species with only one or two 
display types, ritualized jaw sparring might 
substitute for a formal short-distance dis- 
play type. 
ACKNOWLEDGMENTS 
I wish to acknowledge the National Science Foun- 
dation (Grant no. DEB 74—20143) for providing 
support during the writing of this manuscript. 
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