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Speciation divided biologists


What happens during speciation?
Ernst Mayr Scientist
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What happens during speciation? Well, what happens is that, as [Theodosius] Dobzhansky called it, the so-called isolating mechanisms develop. That means, any kind of characteristics of a species and its individuals that separates them or makes them unwilling to mate with an individual of another species. Now, that in animals very often is a behavioral barrier, that the two individuals of two different species meeting with each other have different displays and therefore break it off because they realize they don't belong together. In plants quite often it is a sterility factor; the pollen is indeed carried to the other plant but no fertile seeds develop because there's the sterility factor. All these properties of the genotype that prevent successful cross-breeding are called isolating mechanisms. Now, Dobzhansky when he first proposed the term got a little confused and he included geographic barriers. Geographic barriers are not isolating mechanisms… isolating mechanisms are all properties of genotypes, properties of individuals.

The late German-American biologist Ernst Mayr (1904-2005) was a leading light in the field of evolutionary biology, gaining a PhD at the age of 21. He was also a tropical explorer and ornithologist who undertook an expedition to New Guinea and collected several thousand bird skins. In 1931 he accepted a curatorial position at the American Museum of Natural History. During his time at the museum, aged 37, he published his seminal work 'Systematics and Origin of the Species' which integrated the theories of Darwin and Mendel and is considered one of his greatest works.

Listeners: Walter J. Bock

Walter J. Bock is Professor of Evolutionary Biology at Columbia University. He received his B.Sc. from Cornell and his M.A. and Ph.D. from Harvard. His research lies in the areas of organismal and evolutionary biology, with a special emphasis on functional and evolutionary morphology of the skeleto-muscular system, specifically the feeding apparatus of birds.

Tags: Theodosius Dobzhansky

Duration: 1 minute, 23 seconds

Date story recorded: October 1997

Date story went live: 24 January 2008