Williams - p. 9 
This hypothesis has arisen out of (1) the general observation that the 
amount of orange in the bicolor dewlap of Anolis distichus in Hispaniola 
correlates roughly with major climatic areas within the island - more orange 
in wetter areas, less in drier regions, and (2) the subjective judgment that 
minor variation seems to correlate rather subtly with very local variation 
in vegetation and climate - more orange in the dewlaps of distichus in 
woodland, less in those of open and arid areas. 
Williams and Roughgarden plan joint field surveys of distichus in the 
Dominican Republic, testing this preliminary judgment. They plan to compare 
an index of extent of orange in the dewlap against some vegetational index 
of mesic/arid conditions, 
The bicolor dewlap of A. lineatopus is strikingly like that of A. 
distichus, Again, over major areas a greater extent of the central orange 
and a diminution of the lighter margin correlates with wet versus arid 
climates. There is also certainly considerable local variation in the extent 
of orange, but in Jamaica there has not been yet even an attempt at subjective 
and crude correlation of this local variation with local climate. 
There are other bicolor dewlaps in the West Indies but none but these 
two species emphasize a dark center and a light edge. The most nearly 
similar other species is A. cristatellus of Puerto Rico in which, however, 
the populations with a sharply bicolor dewlap have the center green and the 
edge brownish. 
Cristatellus dewlaps were regularly checked during a circuit of the 
Puerto Rico lowlands in 1973. It was at once evident that whatever the 
function of the bicolor pattern in A. cristatellus there was no possibility 
of fitting the distribution and variability of that pattern into the scheme 
that seems satisfactory for A. distichus and A. lineatopus, The bicolor 
pattern - green center and wide brown edge - is sharpest on the Virgin 
Islands, including arid Culebra (where it was first described); it extends to 
northern and northwest mainland Puerto Rico but is there in variable frequency 
(but without evident correlation with climate), partly replaced by a smudged 
or unicolor brownish dewlap. South of Mayaguez on the west coast at approxi- 
mately the point of vegetational change to acacias and other arid adapted 
plant cover, the cristatellus dewlap becomes nearly consistently unicolor 
brownish. A shift in the reverse direction occurs on the east coast somewhat 
south of Hunacao, There are thus broad trends in geographic variation but 
there appears to be little of the obvious relationship to climatic zones 
characteristic of A. distichus and A. lineatopus. Both of the two major 
dewlap types occur in arid areas and in more or less mesic situations as well. 
