In natural populations of animals and plants, genetic differences among individuals give rise to substantial variation in ability to survive and reproduce, or fitness. This is puzzling, because natural selection would be expected to eliminate fitness-reducing alleles. I investigate the factors maintaining genetic variation for fitness in the fruit fly Drosophila melanogaster. I am also using theory to explore the evolutionary consequences of genetic variation for fitness, especially in the context of sexual selection and mate choice.
Drosophila melanogaster, the workhorse model species, has an interesting life in the wild, because it is fond of breeding in fermenting fruits containing as much as 6% ethanol. Moreover, preference for ethanol and resistance to being poisoned by it vary considerably, and concomitantly, within and among natural populations (Fry 2014; Zhu and Fry 2015). We are investigating how the variation in ethanol resistance may be being maintained by biochemical trade-offs, whereby alleles that promote ethanol resistance produce a fitness disadvantage when flies breed in fruits with little ethanol. We recently documented a polymorphism in aldehyde dehydrogenase, an important enzyme involved in ethanol detoxification, that gives rise to a trade-off between fitness in the presence and absence of ethanol, because the variant with higher catalytic activity against ethanol’s toxic breakdown product acetaldehyde has compromised activity against other toxic aldehydes (Chakraborty and Fry 2016). We are investigating whether trade-offs occur and contribute to the maintenance of polymorphism at other genes involved in ethanol resistance, as well as at genes involved in climatic adaptation, with the goal of identifying unifying biochemical mechanisms that can give rise to fitness trade-offs.
- Zhu, J., and J. D. Fry. 2018. Effects of a low dose of ethanol on mating success of Drosophila melanogaster males: implications for the evolution of ethanol resistance? Entomologia Experimentalis et Applicata 166:801–809.
- Chakraborty, M., and J. D. Fry. 2016. Evidence that environmental heterogeneity maintains a detoxifying enzyme polymorphism in Drosophila melanogaster. Current Biology 26:219-223.
- Chakraborty, M. and J. D. Fry. 2015. Parallel functional changes in independent testis-specific duplicates of Aldehyde dehydrogenase in Drosophila. Molecular Biology and Evolution 32: 1029–1038.
- Zhu, J., and J. D. Fry. 2015. Preference for ethanol in feeding and oviposition in temperate and tropical populations of Drosophila melanogaster. Entomologia Experimentalis et Applicata 155: 64–70.
- Fry, J.D. 2014. Mechanisms of naturally-evolved ethanol resistance in Drosophila melanogaster. Journal of Experimental Biology 217: 3996-4003.
- Yampolsky, L., G. Glazko and J. D. Fry. 2012. Evolution of gene expression and expression plasticity in long-term experimental populations of Drosophila melanogaster maintained under constant and variable ethanol stress. Molecular Ecology, 21: 4287–4299.
- Chakraborty, M., and J. D. Fry. 2011. Drosophila lacking a homologue of mammalian ALDH2 have multiple fitness defects. Chemico-Biological Interactions 191: 296-302.
- Fry, J.D. 2010. The genomic location of sexually antagonistic variation: some cautionary comments. Evolution64-5: 1510-1516.
- Fry, J.D. 2009. Laboratory experiments on speciation. Pages 631-656 in T. Garland and M. Rose, eds., Experimental Evolution: Methods and Applications. University of California Press, Berkeley.
- 2008. A world-wide polymorphism in Aldehyde dehydrogenase in Drosophila melanogaster: evidence for selection mediated by dietary ethanol. Evolution62:66-75.
- 2006. Aldehyde dehydrogenase is essential for both adult and larval ethanol resistance in Drosophila melanogaster. Genet. Res.87:87-92.
- 2005. Widespread correlations between dominance and homozygous effects of mutations: implications for theories of dominance.Genetics171:385-392.
- 2004. On the rate and linearity of viability declines in Drosophila mutation-accumulation experiments: genomic mutation rates and synergistic epistasis revisited.Genetics166:797-806.
- Fry, J. D. 2004. Estimation of genetic variances and covariances by Restricted Maximum Likelihood using PROC MIXED. Pages 11-34 in A. Saxton, ed., Genetic Analysis of Complex Traits with SAS. SAS Institute, Cary, NC. [programs]
- 2003. Detecting ecological trade-offs using selection experiments.Ecology84:1672-1678.
- 2003. Multilocus models of sympatric speciation: Bush vs. Rice vs. Felsenstein.Evolution57:1735-1746.
- 2001. Direct and correlated responses to selection for larval ethanol tolerance in Drosophila melanogaster.Evol. Biol.14:296-309.