natural selection/evolution detected?

Chris Colby colby at bu-bio.bu.edu
Tue Oct 8 14:12:47 EST 1991

	Two recent Nature papers (Brown, et.al and Malhotra and
Thorpe) claim to demonstrate evolution via natural selection in
two different types of lizards. The data they present are
concordant morphological clines and change in morphological
traits over time, respectively.
	My questions are these: Isn't evolution defined as a
change in the gene pool? Can you really claim to have detected
evolution if you haven't demonstrated that the morphological
traits you are measuring reflect heritable differences? Isn't
natural selection differential reproduction among genotypes in
a population? Can you really claim to have demonstrated natural
selection when all you are examining is phenotypes?

	I should add that I think the studies were well designed,
and they certainly _imply_ evolution via natural selection, but I
think the authors overstated their case (esp. see the titles of the
articles -- yeah, I know the editors might have had something to
do with that). Any comments, even "you're just a stupid grad
student -- you've obviously missed the point" would be greatly

Chris Colby
email: colby at bu-bio.bu.edu

Brown, et. al., 1991, Parallel within-island microevolution of
lizards on neighbouring islands, Nature 352: 60-62

Malhotra and Thorpe, 1991, Experimental detection of rapid
evolutionary response in natural lizard populations, Nature
353: 347 - 348

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