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Enzyme Variation in Semi-Isolated Populations of the Mountain Fly Chamaemyia herbarum
Thomas P. Sluss, E. S. Rockwood-Sluss and F. G. Werner
Vol. 31, No. 2 (Jun., 1977), pp. 302-312
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2407751
Page Count: 11
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Eleven populations of the 'mountaintop' fly Chamaemyia herbarum are compared electrophoretically and morphologically across its range from the Colorado Rockies to isolated ranges in southeastern Arizona. Nei's standard genetic distance measurement, based upon seven enzyme loci, identifies distinct northern and southern races, a distinction consistent with morphological data. Southern populations are characterized by greater isolation and smaller population size; therefore, random processes should be an important factor in producing differences between these populations. There is some evidence of random frequency changes but the genetic distance cluster analysis grouped the southern populations according to Dice's Biotic Provinces rather than by distance. Selection due to host differences, temperature differences, or indirect selection on morphological traits may have combined with gene flow between semi-isolated populations to produce the genetic differentiation which we have observed between regions and populations.
Evolution © 1977 Society for the Study of Evolution