Donald I. Williamson

In an article published in the esteemed journal Proceedings of the National Academy of Sciences in 2009, Williamson claimed that the body plan of the adult butterfly and its caterpillar larval stage would have evolved separately in different organisms; then, their phylogenies would eventually merge by hybridisation at a more recent point of their evolutionary history. The study was communicated by Lynn Margulis, via a submission route that at that time allowed academy members of the United States National Academy of Sciences to manage the peer review of a colleague's manuscript. The acceptance for publication led to accusations of "nepotism" and "nonsense" science. Margulis maintained that Williamson's paper was scientifically sound and was only being censured because it didn't adhere to Darwinian orthodoxy. "We don't ask anyone to accept Williamson's ideas – only to evaluate them on the basis of science and scholarship, not knee-jerk prejudice", said Margulis.

He also published speculative works on hybridisation in evolution: Larvae and Evolution (1992, a book foreworded by Lynn Margulis and Alfred I. Tauber), The Origins of Larvae (2003, a revised and extended edition of Larvae and Evolution, not to be confounded with his 2007 article of same title published in the magazine American Scientist), and some articles on the same subject.

To prove the possibility of such hybridizations, Williamson claimed to have succeeded in 1990 in fertilizing sea squirt eggs with sperm from a sea urchin (a species from a different phylum). However, it was later shown that the alleged hybrids were simply sea urchins.

Williamson gained his first degree from the Newcastle division of Durham University in 1942. He earned his PhD from the same university in 1948, and a DSc from Newcastle University in 1972. He worked at the Port Erin Marine Laboratory of the University of Liverpool from 1948 to 1997, and published on Irish Sea plankton, crustacean behaviour and taxonomy, and crustacean larvae.

Donald Irving Williamson (8 January 1922, in Alnham, England – 29 January 2016, in Port Erin, Isle of Man) was a British planktologist and carcinologist.