Monday, January 02, 2006

BUZZ BUZZ, BUZZ BUZZ, EVERYWHERE A BUZZ BUZZ

This stuff is so beautiful. Here Dawkins discusses another force for speciation which seems counterintuitive, but, I think, feels about right, if feelings are allowed in at all when it comes to science. Here he discusses two species of the frog, narrowmouth, found in the United States from coast to coast. The frogs are roughly divided by type into eastern and western species. Their ranges meet in the middle, and an interesting detail reveals itself where the ranges of the two meet.

"As with any two species, there must have been a time when they were one. Something separated them: to use the technical term, the single ancestral species 'speciated' and became two. It is a model for what happens at every branch point in evolution. Every speciation begins with some sort of initial separation between two populations of the same species. It isn't always a geographical separation, but, as we shall see in the Cichlid's Tale, an initial separation of some kind makes it possible for the statistical distribution of genes in the two populations to move apart. This usually results in an evolutionary divergence with respect to something visible: shape or colour or behaviour. In the case of these two populations of American frogs, the western species became adapted to life in drier climates than the eastern, but the most conspicuous difference lies in their mating calls. Both are squeaky buzzes, but each buzz of the western species lasts about twice as long (2 seconds) as the eastern species, and its predominant pitch is noticeably higher: 4,000 cycles per second as against 3,000. That is to say, the predominant pitch of the western narrowmouth is about top C, the highest key on a piano, and the eastern predominant pitch is around the F# below that. These sounds are not musical, however. Both calls contain a mixture of frequencies, ranging from far below the predominant to far above. Both are buzzes, but the eastern buzz is lower. The western call, as well as being longer, begins with a distinct peep, rising in pitch before the buzz takes over. The eastern frog goes straight into its shorter buzz.

"Why go into so much detail about these calls? Because what I have described is true only in the zone of overlap where the comparison between them is clearest, and that is the whole point of the tale. W. F. Blair tape recorded frogs from a good spread of sampling locations across the United States, with fascinating results. In areas where the two species of frogs never meet one another—Florida for the eastern species and Arizona for the western—their songs are much more similar to each other in pitch: the predominant pitch of both is around 3,500 cycles per second: top A on the piano. In areas close to the zone of overlap but not quite in it, the two species are more different, but not as different as they are in the zone of overlap itself.

"The conclusion is intriguing. Something is pushing the calls of these two species apart in the zone where they overlap. Blair's interpretation, which not everybody accepts, is that hybrids are penalized. Anything that helps potential miscegenators to distinguish the species and avoid the wrong one is favoured by natural selection. Such small differences as there may be are exaggerated in just that part of the country where it matters. The great evolutionary geneticist Theodosius Dobzhansky called this 'reinforcement' of reproductive isolation. Not everybody accepts Dobzhansky's reinforcement theory, but the Narrowmouth's Tale, at least, seems to offer support." —Richard Dawkins, THE ANCESTOR'S TALE, pp. 311-312.

Isn't that beautiful and so very clear?


ANOTHER MOVIE FOR YOU

Just watched "Downfall", a German film based on the book by Hitler's private secretary who spent from 1942 through 1945 with the Fuhrer. The film was nominated for an academy award in the category of best foreign film though it did not win. It won several honors in the German equivalents of Hollywood's Oscars.

The film opens briefly with the moment the young woman, Junge, is hired. The Fuhrer is presented as a sweet, reasonable man. Immediately the film cuts to 1945, and the final days in Hitler's bunker in Berlin. You cannot imagine a more brutal and claustrophobic film as this as we watch Hitler lose touch with reality while those around him drink and smoke and stare gloomily at the walls between making brief attempts to tell Hitler what the truth is. Eva throws parties and tries to remain upbeat, as if she has no idea what is going on around her. If anything, the film is underplayed throughout. Who needs dramatic or melodramatic touches when the reality is brutal enough, eh? I don't believe I've seen a more depressing and enlightening film in quite awhile. The final hours of Frau and Joseph Goebbels were particularly disturbing. We are not spared a long scene when Frau Goebbels places a crushed ampule of potassium cyanide into the mouths of each of her five drugged children while they sleep.

The "Downfall" is worth watching if you like history and realism in your films. Watch it on a sunshiny day in midsummer.


THE MAKING OF "DEEP THROAT"

Someone, it may have been Gore Vidal, said in that documentary that when all you have issuing from leadership is lies, lies and more lies, then their can be no basis for truth. No better description of what Bush and company are attempting can be put forth than that idea. Bush's popularity numbers clearly show us how many Americans are unable to tell the truth from a lie. Pretty scary figures for the rest of us, eh, even when the numbers are less than fifty percent?

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