Donald I. Williamson

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Donald Irving Williamson (8 January 1922 – 29 January 2016) was a British scientist who studied tiny sea life. He was born in Alnham, England, and died in Port Erin, Isle of Man. He earned his first degree from the Newcastle division of Durham University in 1942, earned a PhD in 1948 studying Talitrus saltator, and received a Doctor of Science from Newcastle University in 1972. He spent most of his career at the Port Erin Marine Laboratory (University of Liverpool) from 1948 to 1997, researching Irish Sea plankton, crustacean behavior and taxonomy, and crustacean larvae.

Williamson also wrote speculative books about evolution and larvae. His works include Larvae and Evolution (1992) and The Origins of Larvae (2003), which was a revised edition of the earlier book. He proposed a controversial idea called hybridogenesis, suggesting that some larval stages could arise when two distant species hybridize, with parts of one species’ genome directing larval development and parts of the other guiding most adult body plans. He later extended this idea to other animals that undergo complete metamorphosis.

He admitted borrowing the concept from plant hybrids, where distant species can sometimes produce new forms. In 1990, Williamson claimed to have fertilized sea squirt eggs with sea urchin sperm to create such a hybrid, but this was later shown not to be the case. His ideas have been discussed and debated in scientific literature and education resources.

In 2009, Williamson published a study in Proceedings of the National Academy of Sciences proposing that the adult butterfly and its caterpillar could have evolved separately and later joined through hybridization. The paper drew strong criticism from some scientists, with questions about the methods and conclusions. Lynn Margulis supported the work, arguing it should be judged by science rather than prejudice. Several researchers published rebuttals, and others proposed how laboratory tests might more carefully explore the possibility.