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Research Overview

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.

Research Interests

• Genetics of ecological adaptation in Drosophila
• Evolutionary effects of deleterious mutations
• Quantitative-genetic theory and methodology