NANFA-- molecular clocks and Pteronotropis

Dave Neely (rheopresbe_at_hotmail.com)
Mon, 23 Feb 2004 10:14:30 -0600

There's a lot of disagreement about whether molecular evolution is actually
clocklike, and it's clear that the rate varies considerably among gene
regions and among taxonomic groups, and may not always behave clocklike when
you need it to! What you're likely to get is an estimate that has a
confidence limit larger than the estimate... but just for fun, let's assume
that it does work...

Rather than going to all the trouble and labwork doing RFLPs, you could also
download the mitochondrial gene sequences from the Simons et al. 2000 paper
off of GenBank (http://www.ncbi.nlm.nih.gov/ -- your tax dollars actually
do something useful!!) and do a quick comparison. The sequences are somewhat
incomplete, but there's still close to 1100 bp of the cytochrome b gene
available for welaka and hubbsi. These taxa differ by about 11% across this
gene.

A rough rate estimate that folks have been using for cyt b is about 2% per
million years, thus the split between these lineages <may> have occurred
about 5.5 million years ago.

To borrow a line from Bruce, your mileage may vary (by a lot!)

A couple of other taxa may be closlely related to the hypselopterus group,
most notably, redeye chub, Notropis harperi. In life, they even have the
same dorsal sheen and orangish tones...

cheers,
Dave

--
St. Louis, MO


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