Quantitative trait loci affecting knockdown resistance to high temperature in Drosophila melanogaster

• Published in: Molecular ecology Vol. 13; no. 11; pp. 3585 - 3594
• Main Authors: Norry, F.M, Dahlgaard, J, Loeschcke, V
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-11-2004; Blackwell Publishing Ltd
• Subjects: Animal populations; Animals; Chromosome Mapping; Chromosomes; Crosses, Genetic; dominance; Drosophila; Drosophila melanogaster; Drosophila melanogaster - genetics; Drosophila melanogaster - physiology; Gene loci; Genetic Markers; heat-knockdown resistance; heat-shock proteins; heat-stress resistance; High temperature; Hot Temperature; Insects; Lod Score; Male; Microsatellite Repeats; Molecular Sequence Data; QTL; Quantitative Trait Loci; Quantitative Trait, Heritable; Sequence Analysis, DNA; thermal adaptation; X Chromosome - genetics
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/j.1365-294X.2004.02323.x

Knockdown resistance to high temperature is an ecologically important trait in small insects. A composite interval mapping was performed on the two major autosomes of Drosophila melanogaster to search for quantitative trait loci (QTL) affecting knockdown resistance to high temperature (KRHT). Two dramatically divergent lines from geographically different thermal environments were artificially selected on KRHT. These lines were crossed to produce two backcross (BC) populations. Each BC was analysed for 200 males with 18 marker loci on chromosomes 2 and 3. Three X‐linked markers were used to test for X‐linked QTL in an exploratory way. The largest estimate of autosome additive effects was found in the pericentromeric region of chromosome 2, accounting for 19.26% (BC to the low line) and 29.15% (BC to the high line) of the phenotypic variance in BC populations, but it could represent multiple closely linked QTL. Complete dominance was apparent for three QTL on chromosome 3, where heat‐shock genes are concentrated. Exploratory analysis of chromosome X indicated a substantial contribution of this chromosome to KRHT. The results show that a large‐effect QTL with dominant gene action maps on the right arm of chromosome 3. Further, the results confirm that QTL for heat resistance are not limited to chromosome 3.