William George Hill. 7 August 1940—17 December 2021

Abstract

William (Bill) Hill was an internationally acclaimed statistical, population and quantitative geneticist. His work was inspired by practical problems in animal breeding, but is widely applicable to evolutionary biology and human genetics. Bill's work focused on the joint effects of linkage, mutation and genetic architecture in finite populations. He showed that linked loci under selection can interfere with each other, reducing the rate of response to selection. He derived a widely used metric for linkage disequilibrium and showed that there is likely to be substantial linkage disequilibrium between closely linked variants in finite populations. He also showed that the sampling variance of linkage disequilibrium is very large, hampering its use in estimating effective population size or recombination rates. Bill derived sampling variances for inbreeding and realized relatedness between individuals with the same expected degree of relatedness. He raised awareness about the importance of new mutations for quantitative genetic variation and the response to artificial selection, and developed models for the maintenance of quantitative genetic variation by a balance between mutation and stabilizing selection. His experimental designs for estimating heritability and conducting artificial selection experiments have been widely adopted, and were utilized in his own long-term mouse selection experiments. Bill influenced animal breeding directly through consultancies with breeding companies, and his influence on quantitative genetics continues today via his numerous mentees.