Its sort of sad when the computer game SimLife provides more rigorous definitions of scien

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Its sort of sad when the computer game SimLife provides more rigorous definitions of scientific terms than a text- book on the subject. (from SimLife, my comments in []) Evolution: Change in the genetic makeup of a population with time; a theory that the various types of plants and animals have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations. [Great up to the semicolon, the rest could use a little help. Bacteria, viruses, fungi and protists also evolve. Also, the definition hints at, but doesn't explicitly mention common descent.] Natural selection: Differential reproduction in nature, leading to an increase in frequency of some genes or gene combinations and to a decrease in others. [_Very_ good. To be slightly nit-picky, they should have mentioned that it is differential reproduction of genotypes. And, to be really nit-picky, selection doesn't necessarily change the frequency of genes (really, really nitpicky -- try "alleles" instead of "genes"). In balancing selection and frequency-dependent selection, gene frequencies stay the same over generations. _Within_ a generation time, however, they vary. I.e. the gene pool changes from fertilization to reproductive age each generation, but if you choose one part of a generation (say repro age), the gene pool is the same year after year. Consult your local population genetics text to see how to derive the mathematics of this.] Genetic drift: Change in the gene pool purely as a result of chance, and not as a result of selection, mutation or migration. [In all, not too shabby for a computer program. The manual also uses the Vonnegut quote I have been using in my .sig file.] Chris Colby --- email: --- "'My boy,' he said, 'you are descended from a long line of determined, resourceful, microscopic tadpoles--champions every one.'" --Kurt Vonnegut from "Galapagos"


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