The Quarterly Review of Biology (2002) 77, no 3.
From the dust jacket, I expected this to be an historical treatment into antecedents of Darwin's theory on the origin of species. It is part history - "in places I am drawn to ask questions of a historical nature" (p.3) - but the history takes the form of a looking for hints in the 19th century for recent physiological and molecular approaches to the origin of species. Forsdyke believes he has found such hints in the works of Romanes, Gulick, and Bateson, the latter being well known for his rediscovery of Mendel's paper.
Romanes was a staunch supporter of Darwin. Gulick (for most of his life a missionary) is known to some for his discovery of speciation in isolated, but contiguous, populations of Hawaiian snails. Less well known is that Gulick anticipated "organic selection" (the Baldwin effect) by 11 years. Forsdyke admits that his approach is unabashed Whig history, which historians are not supposed to do. But Forsdyke is not a historian, he is a biochemist and molecular biologist.
As his mechanism of speciation, Darwin opted for natural selection over the production of variants - most evolutionary biologists would not define variation as "like does not produce like," or inheritance as "like produces like," as Forsdyke does (p. 16). Bateson wanted to include reproductive criteria in his definition of a species. Romanes's thesis that reproductive or physiological selection occurs before selection on the rest of the phenotype is well laid out.
Forsdyke concludes that, if his interpretation is correct, Romanes and Bateson were light years ahead of their contemporaries. This assumes that we can equate the modern-day knowledge that aspects of species-specific base composition in viral DNA (in particular, C+G% differences) indicate some physiological basis for selection and, specifically, for speciation of organisms other than viruses, which is a real stretch. Romanes and Bateson were seeking a physiological mechanism. Whether we have found that in C+G% differences in viruses remains to be seen. Other aspects of the phenotype of the gene (patterns of methylation, imprinting) are not considered; whether any aspects of the heritable phenotype of the gene relate to speciation (initiation or adaptation) remains to be proven. What Forsdyke does is remind us that individuals other than Darwin were seeking alternate mechanisms of speciation.
Brian K. Hall, Biology, Dalhausie University, Halifax, Nova Scotia, Canada
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