الفهرس 
Drosophila melanogaster
The fruit fly stock and husbandryOnly 14 pages are availabe for public view
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Abstract
Following infection spread into a population, individuals show fitness variation or plasticity based on their genotypes, the environmental stress and the interaction of both factors. In the current study, we used the Drosophila bacteria as a model system to study the response of the D. melanogaster host to bacterial infection under different nutritional regimes(standard vs.restricted)and host heterogeneity (homogenous vs. heterogeneous). The survival % and development time of lines were tested on a standard diet regime. Marked differences in the survivorship were observed between many of the Drosophila isofemale lines and the experimental(heterogeneous population. The experimental population was created with crossing all the isofemale lines together. The two extreme lines in survival % were selected as fit and unfit isofemale lines along with the experimental population were used thereafter. First, standard and protein-restricted diet regimes were tested on the life-history traits of D. melanogaster. Second, several bacterial pathogens were tested as a potential antagonist of Drosophila larvae. D. melanogaster showed a significant decrease in the survival % due to Pectobacterium carotovorum infection. The diet regime and treatment conditions were combined to create four different environments. Life-history traits (survivors % and development time),fecundity,biochemical reserves (protein and lipids contents) and disease resistance activities (phenoloxidase and anti-bacterial peptides) of the key lines were tested under these environments.Interestingly, Drosophila survival was sensitive to P. carotovorum infection, whereas biochemical reserves were affected by diet restriction. Fecundity and disease resistance traits were influenced by both diet restriction and P.carotovorum infection. A tradeoff between survival and fecundity traits was observed in Drosophila. The results of reaction norms of Drosophila survival %, development time and fecundity demonstrated that the isofemale lines were more plastic than those of the heterogeneous population under the range of environments tested.Plasticity of biochemical reserves and disease resistance traits are more common than that of the life-history traits. The obtained results give evidence that the plasticity is considered an important mechanism to help the homogeneous populations to survive the harsh environmental circumstances, whereas the phenotypic variation of the heterogeneous populations is considered the major one. The population that gives fewer survivors was able to give more eggs and show more resistance to infection.