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 fitness-related 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.
ABSTRACT
The present study was undertaken to determine antimicrobial and antioxidant activities of leaf and flower extracts of Caesalpinia pulcherrima, Delonix regia and Peltaphorum ferrugineum. Antimicrobial activity was tested against Staphylococcus aureus, Salmonella typhi, Candida albicans and Cryptococcus neoformans by Agar well diffusion assay. Antioxidant activity was determined by DPPH free radical scavenging assay, ABTS free radical scavenging assay, Ferric reducing assay and Total antioxidant capacity determination. Total phenolic content of extracts was estimated by Folin-Ciocalteau Reagent method. S. typhi and C. neoformans were susceptible to extracts to greater extent than S. aureus and C. albicans among bacteria and fungi respectively. Except C. pulcherrima extract, the leaf extracts were more effective in inhibiting bacteria than flower extracts. Leaf extracts have shown high antifungal activity than flower extracts. The extracts have shown dose dependent scavenging of DPPH and ABTS radicals. Scavenging of ABTS radicals was more efficient than that of DPPH radicals as revealed by low IC50 values. All leaf extracts except C. pulcherrima displayed stronger scavenging activities than flower extracts. Similar results were observed in ferric reducing assay and total antioxidant capacity determination. Total phenolic content was found to be higher in leaf extracts (except C. pulcherrima) than flower extracts. A correlation has been observed between phenolic content of leaf and flower extracts and the antioxidant activity. A marked antimicrobial and antioxidant activity of leaf and flower extracts was observed which may be attributed to the presence of phenolic compounds and other phytochemicals. The plants can be used to control infectious diseases and oxidative damage.