Male size and mating success in Drosophila melanogaster and D. pseudoobscura under field conditions

Wild mating male D. melanogaster and D. pseudoobscura were larger than randomly sampled males. That this was due to size and not a confounding effect of age was confirmed by release experiments with D. melanogaster of standard age; larger males were at a mating advantage with virgin and inseminated females. In both species larger males delivered more courtship and in D. pseudoobscura they won more aggressive encounters. These results on Drosophila in the field confirm and extend those previously obtained in the laboratory.