Trudy F. C. Mackay
THE 2004 GSA Medal is awarded to Trudy F. C. Mackay for her substantial contributions to quantitative genetics. Much of what we now know about the genetic basis of variation in quantitative traits follows from Trudy’s meticulous experiments on bristle number in Drosophila melanogaster, and our future understanding of the molecular mechanisms affecting life span and olfactory behavior will be shaped by Trudy’s current genetic dissection of these traits in Drosophila.
Trudy began her education in biology at Dalhousie University and in 1976 she went to the University of Edinburgh on an 1851 Exhibition Scholarship. There she began a partnership with Douglas Falconer and Bill Hill that has ensured the continuation of excellence of the Edinburgh school of quantitative genetics. A very visible symbol of this continuation was Trudy’s joining with Falconer in 1996 as a coauthor of Principles of Quantitative Genetics, the bible of quantitative genetics since it first appeared in 1960. Trudy is also North American editor of that other Edinburgh beacon, Genetical Research. After a postdoctoral period back in Dalhousie, Trudy returned to Edinburgh in 1980 and began her work with transposable elements. We were fortunate to be able to attract her to North Carolina State in 1987.
Quantitative, or measured, traits are of central importance for human health and agricultural production and so our health and welfare will benefit from an understanding of their genetic basis. Trudy has used the number of sensory hairs of Drosophila melanogaster as a model quantitative trait, and she used transposable elements to study the effects of mutation on such traits. In a series of experiments she constructed lines that differed in the numbers and locations of P elements and quantified their effects on bristle number and viability. Trudy’s training in classical quantitative genetics allowed her to provide statistically sound estimates of pleiotropic and epistatic effects, and she demonstrated the asymmetric and highly leptokurtic nature of P-element effect on bristle number (e.g., Genetics 130: 315-332, 1992). Most of the increase in mutational variation was due to a few lines with large effects, contradicting conventional wisdom that quantitative variation is caused by many genes of small effect. This finding offers hope for the ability to manipulate genes affecting quantitative traits of economic importance or those affecting human health. The P-element studies were accompanied by an investigation, with long-term collaborator Chuck Langley, of naturally occuring variation and a demonstration that this is correlated with variation at the DNA sequence level (Science 266: 1697-1702, 1994).
Although bristle number has proved to be a trait with considerable genetic complexity, Trudy has more recently taken up the challenge of investigating longevity (e.g., Proc. Natl. Acad. Sci. USA 94: 9734-9739, 1997). She has mapped quantitative trait loci (QTL) with effects on life span, survivorship, and mortality in Drosophila melanogaster. Her finding of late age-of-onset QTL effects is consistent with the mutation accumulation hypothesis of senescence, whereas her demonstration of sex-specific QTL effects suggests a novel mechanism for maintaining genetic variation for life span, depending on the existence of QTL genotype by sex interaction for fitness.
Together with husband Robert Anholt, Trudy has been extending her genetic studies to behavioral traits, with an emphasis on odor-guided behavior (e.g., Behav. Genet. 31: 17-27, 2001). In a recent Nature Genetics article (35: 180-184, 2003) Robert, Trudy, and their colleagues reported on a genome-wide expression analysis of smell-impaired and control lines of Drosophila melanogaster. They were able to identify new candidate genes for regulating olfactory behavior.
Trudy’s work on characterizing the genetic basis of quantitative genetic variation follows a tradition of using Drosophila as a model organism that distinguished the work of her mentor Robertson and provided the first QTL interval mapping study of J. M. Thoday in 1961. In her Nature Reviews Genetics article (2: 11-20, 2001), Trudy made an eloquent case for the continued use of Drosophila as a model for human disease studies. This very nice review makes it abundantly clear that these studies will owe much to her very careful experiments and interpretations.
Trudy’s research has made her an international figure and a worthy recipient of the GSA Medal, and her service to her profession demonstrates a generosity of spirit. She has served on the GSA Board of Directors and was a member of the Genetics Editorial Board 1991-2002. Few volumes of Genetics in recent years have not carried several of Trudy’s articles. Trudy has been a voice of support for excellent research in population and quantitative genetics at study sections and review panels. She directs a training grant at North Carolina State and guides a large team of graduate and postdoctoral students. I am fortunate to have her as a colleague—our Society and our profession are fortunate to have her scientific leadership.
- Copyright © 2004 by the Genetics Society of America
