Abstract
Intraspecific competition at the larval stage is an important ecological factor affecting life-history, adaptation and evolutionary trajectory in holometabolous insects. However, the molecular pathways and physiological trade-offs underpinning these ecological processes are poorly characterised. We reared Drosophila melanogaster at three egg densities (5, 60 and 300 eggs/ml) and sequenced the transcriptomes of pooled third-instar larvae. We also examined emergence time, egg-to-adult viability, adult mass and adult sex-ratio at each density. Medium crowding had minor detrimental effects on adult phenotypes compared to low density and yielded 24 differentially expressed genes (DEGs) including several chitinase enzymes. In contrast, high crowding had substantial detrimental effects on adult phenotypes 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. Overall, our findings show that larval overcrowding has a large consistent effect on several molecular pathways (i.e., core responses) with few pathways displaying density-specific regulation (i.e., idiosyncratic responses). This provides important insights into how holometabolous insects respond to intraspecific competition during development.
Original language | English |
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Pages (from-to) | 539-554 |
Number of pages | 16 |
Journal | Insect Science |
Volume | 30 |
Issue number | 2 |
Early online date | 17 Oct 2022 |
DOIs | |
Publication status | Published - 3 Apr 2023 |
Bibliographical note
Open Access via the Wiley Open Access AgreementWe are grateful to EcoGeno Platform from UMS OSUR 3343 in Rennes for access to genomic facilities (2100 Bioanalyzer System and LC480 Roche qPCR System). This study was supported by Drothermal project of The French National Research Agency (ANR-20-CE02-0011-01). JM is supported by the Royal Society (RGS/R2/202220) and a BBSRC grant (BB/V015249/1).
Data Availability Statement
Raw sequence data and the processed gene-count matrix have been deposited at the NCBI Gene Expression Omnibus database (Edgar et al., 2002) and are accessible through GEO Series accession number GSE193120.Keywords
- intrasspecific competition
- larval crowding
- life-history
- trade-offs
- Transcriptomics