Geographical divergence of acoustic signals in Cyprinella galactura, the whitetail shiner (Cyprinidae)

Geographical acoustic signal divergence in fish has been virtually unexplored. Minnows in the genus Cyprinella produce agonistic and courtship sounds during the spawning season, and Cyprinella galactura, with a disjunct distribution in the Ozark and Appalachian mountains, provided a good model for examining signal divergence. We found significant amounts of geographical variation between the four populations of C. galactura examined, and pulse signal parameters (pulse rate, pulse duration, pulse interval) were most important in distinguishing between the populations. Courtship signals differed from agonistic signals, with courtship signals less variable and more stereotyped. Adjacent populations from the Ozark Mountains were more similar than nonadjacent populations. Signal divergence in agonistic signals appears more random, with adjacent populations clustering with nonadjacent populations. Genetic drift may play a role in agonistic signal divergence, while geographical isolation may be responsible for courtship signal divergence.