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The Origin of Species Revisited
I have to preface this review with a story about the time I met Donald Forsdyke. It was May, 2000 and I was in Montreal for the first time in my life (little did I know then that only eight months later I would be moving there). I was there as a substitute speaker at a "bioinformatics in molecular evolution" conference at the University of Montreal, replacing my postdoctoral advisor Ming Li, who had been invited. It was my first exposure to Quebecois culture -- all the other presentations were given in French, a language which up to then I hadn't studied (neither had Ming Li, which makes his invitation in the first place rather inexplicable). All the other presentations? Well, there was one other presenter in English -- a man with an obvious English accent who spoke on secondary structure prediction in DNA -- this was Donald Forsdyke.
At lunch I was obviously drawn to my fellow Anglophone in that sea of Francophones. Forsdyke seemed pleasant enough but seemed to be a somewhat embittered and to have a bit of a chip on his shoulder, something which he seemed to have in common with other molecular evolutionists whom I've met who either worked or studied in Canada (Brian Golding, Ford Doolittle, and Arlin Stoltzfus, for example). Why this should be the case in general I don't know, but this book, which I purchased when I saw it in a bookshop in 2001 but didn't get around to reading until now, goes some ways towards explaining it in Forsdyke's case.
The first thing one should know about the book is that while the subtitle would lead you to think that this is a history of science in the sense of a historian trying to present an objective picture of the past, this is not the case. The book is really just about three people, George Romanes, William Bateson, and Donald Forsdyke himself -- the first two are lauded as overlooked precursors to Forsdyke himself. This isn't to say the book is necessarily bad, only that it is, to borrow a phrase used to describe Darwin's own book, "one long argument".
But what is Forsdyke arguing about? Basically it stems from the observation (which I've made myself), that despite entitling his book On the Origin of Species, Darwin actually wrote very little on the origin of species themselves, instead focussing on the spread of favorable traits within a species. When Darwin wrote about the origin of species at all, he seemed to assume that they arose by some chance physical separation of a small group from the main population -- an idea that of course came naturally to someone who had observed the similar, but different, species of birds and tortoises on the various Galapagos islands. Darwin certainly knew that matings between different species usually resulted in no or sterile offspring (he even wrote a chapter about it in the Origin), but was inclined to consider this a relatively unimportant effect -- speciation, in Darwin's view, simply lead for some unknown reason to hybrid infertility -- perhaps it was even selected for.
George Romanes, despite being a sort of unofficial grad student/postdoc of Darwin's, was the first proponent of an alternative hypothesis -- that hybrid infertility could be a cause of speciation itself (Romanes' "physiological selection"). Unfortunately, living as he did in the 19th century, prior to any useful theories of heredity, there really wasn't any way to confirm or refute such a claim. Additionally, Thomas Henry Huxley, "Darwin's bulldog", had his hands full fighting off the opponents of evolution and had no patience with allies like Romanes who refused to present themselves to the public as members of a homogenous Darwinian front (the fact that Romanes, like Alfred Wallace, had a side interest in spiritualism and seances didn't help manners, of course). Such things lead to Romanes' isolation from the Darwinian inner circle and to his obscurity today.
The second person who Forsdyke presents as holding a similar hypothesis is the much less obscure William Bateson, whom any student of genetics will recognize as one of the earliest geneticists and one of the researchers who rediscovered Mendel's laws in 1900. However, while Bateson is remembered for his contributions to genetics, he lived at a time when Mendelism and Darwinism were seen as competing rather than complementary theories and thus much of his work on evolution, which was presented in a non-Darwinian framework, has been forgotten. Part of this work was the idea that hybrid infertility might arise from a failure of "factors" on homologous chromosome to either bind or separate once bound -- in other words, DNA hybridization before DNA was known to be the genetic material.
This brings us up to Forsdyke himself. Basically he seems fascinated with GC-ratios as the answer to hybrid infertility. He certainly drives the point home that different species have different GC ratios, and that GC-ratios are correlated with features of secondary structure (such as stemloops) which can interfere with DNA hybridization and thus cause infertility. What Forsdyke does not make clear is what, if any, evidence supports GC changes as a source of speciation rather than neutral drift after speciation. He seems to suggest that resistance to his hypothesis derives from its questioning parts of the Modern Synthesis, but at least part of this resistance may stem from Forsdyke's explanation (or lack thereof) of why he thinks GC-ratios cause speciation. I feel a bit odd taking on the role as defender of the pre-molecular Modern Synthesis, which I normally agree is an impediment to modern molecular evolution, but I just don't see the second half of Forsdyke's argument. I rather wish I could run into Forsdyke again and see if he could explain what he's getting at in person.
Last edited on Thursday, August 5, 2004 12:37:25 pm [by JB. For any updates please go to JB's webpage. DRF].
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Last edited 17 Sep 2004 by Donald Forsdyke