1970] 
Carde, Shapiro , Clench — Lethe 
99 
a prior western distribution for eurydice, but does not help in 
dating it. We have no grounds for estimating evolutionary rates in 
this group; all that can be said now with some confidence is that 
eurydice and appalachia were more likely allopatric than sympatric 
in the Wisconsin (and appalachia and portlandia more likely sym- 
patric). 
The critical evidence concerns character displacement. We have 
found no morphological character displacement in sympatric vs. 
allopatric populations of Lethe eurydice and L. appalachia. One 
of us (Clench) believes he has observed behavioral character dis- 
placement between them in Pennsylvania, within the area of general 
sympatry; in certain localities where only one species occurs, it ap- 
pears that the habitat selection is not so rigorous as elsewhere. This 
needs additional study and quantification. Another geographic area 
also bears close investigation in this connection. Specimens of eurydice 
from southeastern New York (Orange, Rockland, and Westchester 
Counties) are somewhat anomalous, tending to vary in color and 
pattern (but not genitalia) toward appalachia. We have' seen very 
few specimens from outside this small area which we would hesitate 
to classify to species by color and pattern. The area is completely 
surrounded by normal, sympatric, well-differentiated populations of 
both. It is thus critical to determine the ecology of these anomalous 
insects. Should appalachia be rare or absent, and eurydice occupying 
its niche at least in part, one would have a powerful argument for 
character displacement as the origin of the habitat difference. (There 
is a chance of natural hybridization due to man’s extensive disturb- 
ance of Lethe habitats in southeastern New York.) 
There are, then, two basic questions: Did the behavioral and 
food plant differences between the American eurydice and portlandia 
groups evolve independently, or largely as a result of competition? 
Did the sharp habitat selection between eurydice and appalachia in 
close sympatry evolve in isolation, or was it intensified by behavioral 
character displacement? 
On the first point, any evolutionary scenario will require much 
more comparative data on the Asiatic species than is readily avail- 
able. Only a comprehensive revision, identifying the closest relatives 
of the American species and comparing their biologies, will allow 
a convincing argument. 
On the second point, field studies in areas of allopatry will be 
critical. It should b-e noted that while we suspect the eurydice - 
appalachia habitat difference may have evolved to prevent competition 
