1979] 
North & Shaw — Pterophylla camellifolia 
373 
relict populations (Smith 1965). Such fragmentation facilitates popu¬ 
lation differentiation. As for P. camellifolia, fragmentation is most 
effective at the periphery of their range where habitat and animals are 
climatically limited. P. camellifolia in Iowa consists of a number of 
relatively small isolated colonies which are undergoing morphologi¬ 
cal and behavioral differentiation (a remarkable example is western 
colony #1 [Table 3] within which some males produce up to 30 
pulses/chirp) and which may eventually become reproductively iso¬ 
lated populations. 
The intrapopulation variation of colonies of western and northern 
P. camellifolia could be a result of 1) inbreeding of small isolated 
populations, and/or 2) gene exchange between formerly continuous 
western and northern populations. Further field studies are necessary 
to determine the extent of the distribution of the western and north¬ 
ern populations outside Iowa. Crossing experiments as well as choice 
and non-choice phonataxis experiments, involving playbacks of call¬ 
ing sounds to virgin females of both populations, are necessary for a 
decision regarding the taxonomic affinity of northern and western P. 
camellifolia. 
Acknowledgments 
We wish to thank Dr. D. F. Cox, Department of Statistics, Iowa 
State University, for assistance with the statistical analysis, and Dr. 
R. E. Lewis, Department of Entomology, Iowa State University, for 
reviewing the manuscript. Special thanks are due Ms Patti Hanson 
for prodigious assistance in the survey and the collection of 
specimens. 
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