Patterns of nucleotide variation consistent with the action of natural sele
ction have been discovered at a number of different gene loci. Here, pherom
one-binding proteins (PBPs) are examined to determine if selection has acte
d to fix amino acid changes in PBPs in lineages in which pheromone changes
have occurred. PBPs from five different species of moths in the genus Chori
stoneura were sequenced, along with the PBP of Argyrotaenia velutinana, whi
ch serves as an outgroup. Three independent major pheromone changes are rep
resented within this group of five Choristoneura species. Two different lin
eages show evidence for selection based on polymorphism and divergence comp
arisons and comparisons of rates of replacement evolution to silent and non
coding evolution. Along one of these lineages, leading to Choristoneura fum
iferana, there has been a change to an aldehyde pheromone from an acetate p
heromone. The second branch does not appear to be associated with a major p
heromone change. Other branches in the tree show a trend toward greater rep
lacement fixation than expected under neutrality. This trend could reflect
undetected selective events within this group of PBPs. Selection appears to
have acted to fix amino acid changes in the PBP of moths from the genus Ch
oristoneura, but it is not clear that this selection is due to pheromone ch
anges between species.