title: Direct and correlated responses to laboratory selection for body melanisation in Drosophila melanogaster: support for the melanisation-desiccation resistance hypothesis.
abstract: For Drosophila melanogaster, cuticular melanisation is a quantitative trait, varying from no melanin to completely dark. Variation in melanisation has been linked with stress resistance, especially desiccation, in D. melanogaster and other species. As melanism has a genetic component, we selected melanic and non-melanic phenotypes of D. melanogaster in order to confirm the association of desiccation resistance and rate of water loss with cuticular melanisation previously reported for this species. A bidirectional selection experiment for dark (D1-D4) and light (L1-L4) body colour in D. melanogaster was conducted for 60 generations. We observed a 1.6-fold increase in abdominal melanisation in selected dark strains and a 14-fold decrease in selected light strains compared with control populations. Desiccation resistance increased significantly in the dark-selected morphs as compared with controls. The observed increase in desiccation resistance appeared as a consequence of a decrease in cuticular permeability. Our results show that traits related to water balance were significantly correlated with abdominal melanisation and were simultaneously selected bidirectionally along with melanisation.
authors.affiliation: Lab No. 13, Drosophila Genetics Laboratory, Maharshi Dayanand University, Rohtak-124001, Haryana, India. seema.ramniwas@gmail.com
authors.forename: Seema
authors.initials: S
authors.lastname: Ramniwas
authors.forename: Babita
authors.initials: B
authors.lastname: Kajla
authors.forename: Kapil
authors.initials: K
authors.lastname: Dev
authors.forename: Ravi
authors.initials: R
authors.lastname: Parkash
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D005075:Biological Evolution; D004331:Drosophila melanogaster / Q000502:physiology*; D008543:Melanins / Q000502:physiology*; D008954:Models, Biological; D010858:Pigmentation / Q000502:physiology*; D012641:Selection, Genetic / Q000235:genetics*; D014870:Water Loss, Insensible / Q000235:genetics / Q000502:physiology*
chemical_list: D008543:Melanins