Behaviour genetics deals with complex phenotypes which respond flexibly to environments animals experience. Change of phenotype in response to environment is phenotypic plasticity. A central question is how genes influence plasticity. I study plasticity and gene by environment interactions (GEI) relating to behaviours,
metabolic, and genomic phenotypes of adults of the fruit fly Drosophila melanogaster.
Chapters 1-3 study cuticular hydrocarbon (CH) levels of male flies. Chapter 1 shows male CH levels respond to time of day and light. Methods are developed to reduce high variability of CH. I show variation in
CH parallels activity of two classes of CH synthesis hormones. Analysis of rate of variation gives estimates of turnover rates of CH and the metabolic cost of signaling. Chapter 2 studies mixed groups of genetically
different flies, “hosts” and “visitors”. GEI of CH are found with both abiotic factors and with social mix. Social mix results in GEI as strong as abiotic factors. Indirect Genetic Effects (IGE) theory is used to show frequency-dependent IGE interactions. Chapter 3 shows that males in mixed social environments reduce expression of clock and CH synthesis genes, resulting in different signals. Females mate more often with males in a mixed group than with single-genotype males. Plasticity in male gene expression in response to social environment leads to different signals, mating levels, and potentially different fitness. Chapter 4 deals with behaviour, metabolite, and genomic phenotypes in flies differing in foraging gene alleles, as the food environment is changed. Strong GEI is found, structured by food type, chemical class
of metabolite, and gene metabolic roles. A concept called “relative nutrient sensitivity” suggests an interaction
between foraging and the insulin signaling pathway. I demonstrate epistasis between for and insulin with quantitative genetic methods and bioinformatics.
These results lead to the conclusion that GEI are common in many fly phenotypes in response to well studied environments such as food and less studied ones such as social group. Some implications of this for
maintenance of genetic variance are discussed.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/19280 |
| Date | 03 March 2010 |
| Creators | Kent, Clement F. III |
| Contributors | Levine, Joel, Sokolowski, Marla B. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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