In biology, a cline is a measurable gradient in a single characteristic of a species across its geographical range. Clines usually have a genetic, or phenotypic character. They can show either smooth, continuous gradation in a character, or more abrupt changes in the trait from one geographic region to the next.
Bergmann's Rule demonstrated showing the difference in size between a larger northern fox, whose range spans colder regions, and a smaller desert fox, whose range is primarily in hot regions
Sir Julian Sorell Huxley was a British evolutionary biologist, eugenicist, and internationalist. He was a proponent of natural selection, and a leading figure in the mid-twentieth century modern synthesis. He was secretary of the Zoological Society of London (1935–1942), the first Director of UNESCO, a founding member of the World Wildlife Fund, the president of the British Eugenics Society (1959–1962), and the first president of the British Humanist Association.
Huxley in 1922
English Heritage blue plaque at 16 Bracknell Gardens, Hampstead, London, commemorating Julian, his younger brother Aldous, and father Leonard
T. H. Huxley with Julian in 1893
Great crested grebes