Career
He has collaborated extensively with Charles Sibley, primarily at Yale University. By 1987, both Ahlquist and Sibley had left Yale. In January 1991 (often listed as 1990), Charles Sibley and Ahlquist published Phylogeny and Classification of Birds, which presented a new phylogeny for birds based on deoxyribonucleic acid-deoxyribonucleic acid hybridisation techniques, known as the Sibley-Ahlquist taxonomy.
At that time, he was an associate professor of zoology at Ohio University.
In 1999, Ahlquist was retired.
