The transcriptomic signature of physiological trade-offs caused by larval overcrowding in Drosophila melanogaster

This study examined the transcriptomic response of Drosophila melanogaster larvae to crowding conditions. The phenotypic and transcriptomic changes from low larval density (5 eggs/ml) to medium density (60 eggs/ml) were minor, yielding somewhat reduced adult fitness and only 24 differentially expressed genes (DEGs). In contrast, high density (300 eggs/ml) caused extensive detrimental effects on adult fitness and yielded 2107 DEGs. Among these, upregulated gene sets were enriched in sugar, steroid and amino acid metabolism as well as DNA replication pathways, whereas downregulated gene sets were enriched in ABC transporters, Taurine, Toll/Imd signalling and P450 xenobiotics metabolism pathways. mRNA from larval pools (10 larvae per pool); three larval densities (low: 5 eggs/ml; medium: 60 eggs/ml; high: 300 eggs/ml); three replicates per density