Quantitative geneticist who has made seminal contributions to understanding the nature of genetic variation.
Molecular genetic variation studies have shown that regions of the genome prone to low recombination rates experience higher rates of accumulation of deleterious mutations and lower rates of adaptive substitutions. In 1966, William (Bill) Hill provided the mechanism that explains this, as well as other related phenomena in evolutionary genetics (such as a lower frequency of optimal codons in low crossover regions). This mechanism became known as the Hill-Robertson effect, as Bill discovered it while a doctoral student with Alan Robertson. The Hill-Robertson effect is the reduction in the efficiency of selection against deleterious mutations and in favor of advantageous mutations that occurs when linked non-neutral alleles interfere with each other. This can be understood in terms of the reduction in effective population size that occurs as a result of selection reducing the long-term contribution of individuals carrying advantageous alleles.
Credit: Photography © AK Purkiss
Bill Hill died on December 17, 2021 in Edinburgh, UK. He was born in Hemel Hempstead, UK on August 7, 1940, and studied at Wye College London (BSc, 1961) and University of California Davis (MS, 1963), before joining the University from Edinburgh where he completed his doctorate. and spent most of his college career.
Bill’s name will be remembered for the Hill-Robertson effect, a fact he accepted but which I think he may not have been entirely comfortable with. A major impact of his work on the joint effects of natural selection and recombination in finite populations is that it provides an evolutionary advantage of recombination – namely that the hitchhiking of mutations that increase the rate of recombination attenuates Hill-Robertson effects, so attachment of recombination modifiers increases rates of adaptive substitution and removal of deleterious mutations. In population genetics, Bill has also done important work on the phenomenon of linkage disequilibrium, the non-random association of alleles at more than one locus. He developed the basic framework for quantifying non-random associations and establishing that genetic drift can increase linkage disequilibrium. This has had many applications for quantitative trait locus and quantitative trait association mapping, and in particular for understanding the genetic basis of variation in complex disease traits in humans. The major practical implications of this work occurred mainly decades after the publication of its seminal papers.
Bill’s main area of research was quantitative genetics, the study of the inheritance of continuously varying traits such as growth rate, milk production and fitness, and he was the preeminent quantitative geneticist of his generation. He has made fundamental contributions to our understanding of the genetic basis of quantitative variation, such as the role of mutations in explaining long-term responses to artificial selection, which often continue in experimental populations as well as in animals. and domestic plants. This work inspired a generation of experimental quantitative geneticists to conduct long-term mutation selection and accumulation experiments to quantify and characterize the quantitative variation resulting from new mutations. He has also worked on the consequences of finite population size and its implications for sustaining long-term selection responses and maintaining variation. Bill had a long association with the animal breeding industry, and his influence led to the application of advanced quantitative genetic methodologies, including the optimal use of information from related individuals to make decisions. Selection. He was also aware of the possible adverse effects of selection focused solely on production traits such as high growth rate, which can lead to undesirable correlated effects (eg, skeletal deformity in broiler chickens). He advocated that such unsustainable effects could be avoided by collecting data on body condition, disease, conformation and associated traits and including them in a multi-trait selection scheme. His work has been particularly impactful in increasing the rate of genetic progress in dairy cattle in the UK, which was recognized with his honor of the OBE (Officer of the Order of the British Empire) in 2004.
Bill has a lasting impact through his scientific research, but his long-term influence has also come from his mentorship of students and research associates, many of whom have gone on to successful careers in academia and industry. He has supervised over 50 research students at the University of Edinburgh and its associated institutions. Bill was an extremely supportive mentor. He usually walked around his group before the morning coffee break (which was in Alan Robertson’s office down the hall when I was doing my PhD) and often started with the same question: “What did you discovered? “. It wasn’t because he expected someone to actually discover something new every day; instead, I think it was a nice way to open up the conversation about where we were at with the project. We would then talk about what the latest results meant and what could be done next. He showed an incredibly keen interest, but it was never overbearing and he was happy for the students to go their own way with their projects, which is vital to becoming an independent scientist. What mattered to Bill was doing good science. Bill was also incredibly efficient at reading and commenting on manuscripts, and always provided insightful comments – usually the next day, despite his extremely busy academic schedule.
Among Bill’s long list of honors and awards, he was elected a Fellow of the Royal Society of Edinburgh in 1979 and of the Royal Society in 1985, and received the Royal Society of Edinburgh Royal Medal in 2005, the Royal Society Darwin Medal in 2018 and the Genetics Society Medal in 2019.
PDK completed his doctorate under the supervision of Bill Hill.
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Keightley, PD William G. Hill (1940–2021).
Nat Ecol Evol (2022). https://doi.org/10.1038/s41559-022-01687-1