[Taxacom] Yellow brick road

John Grehan jgrehan at sciencebuff.org
Wed Nov 5 15:52:37 CST 2008

As mentioned in an earlier post, I am digging into the purported wealth of molecular sequence evidence for the human-chimp-gorilla-orang phylogenetic pattern. Its not a straight forward process. For example, I started with Enard & Pääbo (2004) as a fairly recent study that presents a human-chimp-gorilla-orang phylogeny. 

Enard & Pääbo (2004) do not present actual evidence, but cite Goodman (1999) as the source. Goodman (1999) in turn cites Goodman et al (1998) and "in press (which was not cited).

Goodman (1998) refers to the beta globin gene as giving a "well resolved picture" but does not present the evidence. He cites Koop et al (1989) [incorrectly as 1998], Bailey et al., 1992, and Porter et al 1997a.

At this time I have looked at Koop et al (1989) - They include one data set (eta sequences of beta globin gene) that includes humans and each of the great ape genera along with three monkey species, a tarsier, a galago, and two lemurs. A total of 2373 gamma sequences are presented, but the last few exclude two taxa so if I just look at the 2318 sequences that cover all taxa there are only eight positions where there are bases not present outside humans and great apes. If I treat the remaining 7 species as the outgroup then these eight positions comprise the only putative apomorphies. All of them cluster humans and great apes. 

I bet that if more primate species were included in the outrgroup, these eight putative apomorphies would disappear in a puff of cladistic smoke.

Koope et al (1989) generate a phylogenetic tree for the eta sequence that gives the human-chimp-gorilla-orangutan pattern, but it beats me as to where this came from. Cladistically this appears to be nonsense - there are no such apomorphies in the data set.

Any comments? Criticisms? Denouncements? Mistakes?

Goodman et al (1998) Mol Phylogenetics and evol 9: 585-598
Koop et al (1989) Mol. Biol. Evol. 6: 580-612

John Grehan

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