CLINAL VARIATION AND SELECTION OF MDH ALLOZYMES IN HONEY-BEE POPULATIONS

Latitudinal dines of malate dehydrogenase-1 (MDH-1) allozymes occur wi thin honey bee populations on three continents: Europe, North America and South America. The North and South American populations are introd uced and demonstrate that Mdh allelic dines were established within th e last 150 years. The frequency of the 'medium' electrophoretic allele increases in frequency with increasing latitude while the 'fast' alle le decreases with latitude on all the three continents. The dines are best explained by the average daily high temperature for July on all c ontinents. These parallel dines provide evidence for selection on Mdh alleles in honey bees.