Authors: Jaya Handa K T Chandrashekara Khushboo Kashyap Geetanjali Sageena Mallikarjun N Shakarad
Publish Date: 2014/07/05
Volume: 39, Issue: 4, Pages: 609-620
Abstract
Darwinian fitness in holometabolous insects like the fruit fly Drosophila melanogaster is reported to be positively correlated with body size If large individuals in a population have higher fitness then one would expect directional selection to operate leading to uniformly large individuals However size polymorphism persists in nature and needs further probing We assessed the effect of body size on some of the fitness and fitnessrelated traits in replicate populations of genotypically large genotypically small and phenotypically small D melanogaster flies In this study the time taken to attain reproductive maturity and copulation duration were independent of fly size Fecundity and longevity of large females were significantly higher when they partnered genotypically small males than when they were with genotypically larger or phenotypically small males The increased female longevity when in association with genotypically small males was not due to selective early death of males that would release the female partner from presumed cost of persistent courtship On the contrary the genotypically as well as phenotypically small males had significantly higher longevity than large males The virility of the genotypically small males was not significantly different from that of genotypically large males Our results clearly show that selection on body size operates in the opposite direction disruptive selection for the two genders thus explaining the persistence of size polymorphisms in the holometabolous insect Drosophila melanogaster
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