Metabolic and immunological responses ofDrosophila melanogasterto dietary restriction and bacterial infection differ substantially between genotypes in a population

Abstract

To respond to changing environmental conditions, a population may either shift toward better‐adapted genotypes or adapt on an individual level. The present work aimed to quantify the relevance of these two processes by comparing the responses of defined Drosophila melanogaster populations to different stressors. To do this, we infected two homogeneous populations (isofemale lines), which differ significantly in fitness, and a synthetic heterogeneous population with a specific pathogen and/or exposed them to food restriction. Pectobacterium carotovorum was used to infect Drosophila larvae either fed standard or protein‐restricted diet. In particular, the two homogeneous groups, which diverged in their fitness, showed considerable differences in all parameters assessed (survivorship, protein and lipid contents, phenol‐oxidase (PO) activity, and antibacterial rate). Under fully nutritious conditions, larvae of the homogeneous population with low fitness exhibited lower survivorship and protein levels, as well as higher PO activity and antibacterial rate compared with the fitter population. A protein‐restricted diet and bacterial infection provoked a decrease in survivorship, and antibacterial rate in most populations. Bacterial infection elicited an opposite response in protein and lipid content in both isofemale lines tested. Interestingly, the heterogeneous population showed a complex response pattern. The response of the heterogeneous population followed the fit genotype in terms of survival and antibacterial activity but followed the unfit genotype in terms of PO activity. In conclusion, our results show that defined genotypes exhibit highly divergent responses to varying stressors that are difficult to predict. Furthermore, the responses of heterogeneous populations do not follow a fixed pattern showing a very high degree of plasticity and differences between different genotypes.

Allopatric populations of Drosophila ananassae exhibit different degree of trade-off for evolving immune response against bacterial infection

“…Immune response in host against pathogen evolves rapidly among different organisms including Drosophila (Lazzaro and Little 2009; Lazzaro et al 2004Lazzaro et al , 2006Lazzaro et al , 2008 and it demands cost that is being met by 'trading-off' with other physiologic, morphologic or life history traits (Ye et al 2009). Phenotypic plasticity helps in modulation of the above mentioned energy requiring attributes to enable the host to maintain a stable defence system that has evolved against the intruding pathogens (Chen et al 2017; Meshrif et al 2022). Several studies have been conducted to characterize various 'trade-off' between elevated immune response in Drosophila and its life history traits.…”