Jon Edward Ahlquist is an American molecular biologist and ornithologist

Ornithology

Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...

 who has specialized in molecular phylogenetics. He has collaborated extensively with Charles Sibley

Charles Sibley

Charles Gald Sibley was an American ornithologist and molecular biologist. He had an immense influence on the scientific classification of birds, and the work that Sibley initiated has substantially altered our understanding of the evolutionary history of modern birds.Sibley's taxonomy has been a...

, primarily at Yale University

Yale University

Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...

.
By 1987, both Ahlquist and Sibley had left Yale.
In 1988, Ahlquist and Sibley were awarded the Daniel Giraud Elliot Medal

Daniel Giraud Elliot Medal

The Daniel Giraud Elliot Medal is awarded by the U.S. National Academy of Sciences "for meritorious work in zoology or paleontology published in a three- to five-year period." Named after Daniel Giraud Elliot, it was first awarded in 1917....

 by the National Academy of Sciences

United States National Academy of Sciences

The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...

. In January 1991 (often listed as 1990), Charles Sibley

Charles Sibley

Charles Gald Sibley was an American ornithologist and molecular biologist. He had an immense influence on the scientific classification of birds, and the work that Sibley initiated has substantially altered our understanding of the evolutionary history of modern birds.Sibley's taxonomy has been a...

 and Ahlquist published Phylogeny and Classification of Birds, which presented a new phylogeny for bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s based on DNA-DNA hybridisation

DNA-DNA hybridisation

DNA-DNA hybridization generally refers to a molecular biology technique that measures the degree of genetic similarity between pools of DNA sequences. It is usually used to determine the genetic distance between two species...

 techniques, known as the Sibley-Ahlquist taxonomy

Sibley-Ahlquist taxonomy

The Sibley-Ahlquist taxonomy is a bird taxonomy proposed by Charles Sibley and Jon Edward Ahlquist. It is based on DNA-DNA hybridization studies conducted in the late 1970s and throughout the 1980s....

.
At that time, he was an associate professor of zoology

Zoology

Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

 at Ohio University

Ohio University

Ohio University is a public university located in the Midwestern United States in Athens, Ohio, situated on an campus...

. In 1999, Ahlquist was retired (Ahlquist, 1999).