Leigh M. Van Valen (born 1935) is an American evolutionary biologist. As of 2008^[update] he is professor in the Department of Ecology and Evolution at the University of Chicago.

Amongst other work, Van Valen's proposed Law of Extinction drew upon the apparent constant probability (as opposed to rate) of extinction in families of related organisms, based on data compiled from existing literature on the duration of tens of thousands of genera throughout the fossil record. Van Valen proposed the Red Queen hypothesis (1973) as an explanatory tangent to the Law of Extinction. The Red Queen hypothesis captures the idea that there is a constant 'arms race' between co-evolving species. Its name is a reference to the Red Queen's race in Lewis Carroll's Alice Through the Looking Glass, in which the chess board moves such that Alice must continue running just to stay in the same place.

Van Valen also defined the Ecological Species Concept in 1976, in contrast to Ernst Mayr's Biological Species Concept. In 1991 he proposed that HeLa cells be defined as a new species and be named Helacyton gartleri.

[edit] Publications

• Leigh Van Valen (1973). A new evolutionary law. Evolutionary Theory, 1:1-30.
• Leigh Van Valen (1976). Ecological species, multispecies, and oaks. Taxon, 25:233-239.
• Leigh Van Valen and Virginia C. Maiorana (1991). HeLa, a new microbial species. Evolutionary Theory, 10:71-74

[edit] External links

• Ecology homepage

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