海鸥系列之四
看看当代最著名的进化论科学家，来自牛津的Richard Dawkins怎么看待Ring Species和Herring Gull：
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The best known case is the Herring Gull/Lesser Black-backed Gull ring. In Britain these are clearly distinct species, quite different in colour. Anybody can tell them apart. But if you follow the population of Herring Gulls westward round the North Pole to North America, then via Alaska across Siberia and back to Europe again, you notice a curious fact. The ‘Herring Gulls’ become less and less like Herring Gulls and more and more like Lesser Black-backed Gulls until it turns out that our European Lesser Black-backed Gulls actually are the other end of a ring that started out as Herring Gulls. At every stage around the ring, the birds are sufficiently similar to their neighbours to interbreed with them. Until, that is, the ends of the continuum are reached, in Europe.
At this point, the Herring Gull and the Lesser Black-backed Gull never interbreed, although they are linked by a continuous series of interbreeding colleagues all the way round the world. The only thing that is special about ring species like these gulls is that the intermediates are still alive. All pairs of related species are potentially ring species.
The intermediates must have lived once. It is just that in most cases they are now dead.” - Dawkins, R. Gaps In The Mind from A Devil’s Chaplain, p21, 2003; See also The Ancestors Tale p302, 2004
Dawkins印刷这两本书时，楼上提供的Herring Gull和Lesser Black-backed Gull可以Interbreeding的证据已经出版，这篇文章更是提到了更多、更早的这些海鸥之间可以Interbreeding的证据：
http://www.researchgate.net/publication/230822394_Hybrid_gulls_in_Belgium_an_update
Interbreeding among large white-headed gulls in the Low Countries has been doc-umented by various authors, including
Tinbergen (1929), van Dobben (1931), Voous (1946), Cottaar & Verbeek (1994), Vercruijsse (1995) and Cottaar (2004) in the Nether-lands, and Vercruijsse et al. (2002a,b) and Adriaens (2003) in Belgium. Eight years have now passed since the last paper on the subject, during which time more research has been carried out and colour-ringing projects have produced a wealth of new information.
To be continued
