John Burdon Sanderson Haldane had no formal education in any scientific subject and yet he became a commanding figure in biochemistry, evolutionary theory, genetics, and physiology, publishing over 400 papers and 24 books.
Ronald Fisher was an evolutionary biologist and statistician. He is perhaps best known for inventing an array of revolutionary statistical procedures that could be used within the natural sciences, but his contribution to our understanding of evolution goes far beyond the statistical tests with which he most widely and commonly associated.
D’Arcy Wentworth Thompson (1860-1948) was a Scottish biologist, and a gifted mathematician, naturalist and classical scholar. His work provides a quintessential example of how seemingly disparate disciplines can be combined to develop novel approaches to understanding evolution.