More on reticulation

Curtis Clark jcclark at CSUPOMONA.EDU
Wed Feb 6 18:49:44 CST 2002

At 01:38 PM 2/5/02, STEPHEN MANNING wrote:
>But yet botanical cladograms are constructed the same way as others, aren't
>they?  If so, and for as long as this has occurred and continues to occur,
>that is a warning flag for the methodology as a whole, from my

That's your call, of course, but most botanists I know won't reject a
technique just because it's not infallible.

>And how about the degree to which cladistic (and other?)
>botanical studies use chloroplast and ribosomal rather than nuclear genes
>from which to generalize?

First, ribosomes don't have genes, they are the results of genes:
cytoplasmic ribosomes are coded by nuclear DNA, chloroplast and
mitochondrial ribosomes by their respective genomes.

Second, the comparison of chloroplast and nuclear gene trees is a common
method for studying reticulation (as one line of evidence, of course).

Third, chloroplast and mitochondrial genes are uniparental, but nuclear
genes can recombine contributions from both parent species. These genetic
chimeras are another way to study reticulation.

Curtis Clark        
Biological Sciences Department             Voice: (909) 869-4062
California State Polytechnic University      FAX: (909) 869-4078
Pomona CA 91768-4032  USA                  jcclark at

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