[Taxacom] The difference

Don.Colless at csiro.au Don.Colless at csiro.au
Sun Oct 28 01:14:49 CDT 2007

Although not very active in the field any longer, I must enter my long-held opinion that mixing molecular and morphological data sets is quite illogical - on the simple grounds of redundancy and probable grossly unequal weighting of characters. If the genomic composition is ultimately responsible for total morphology (the Hennigian holomorph), but with the fine detail quite unknown, then said mixing simply entails a complex  network of double entry without weighting. So, why not stick to parallel studies of the two, with subsequent analysis of any serious differences. This business about "total evidence" is nonsense if it entails the effects I've mentioned. 

Don Colless,
Div of Entomology, CSIRO,
GPO Box 1700,
Canberra. 2601.
Email: don.colless at csiro.au
Tuz li munz est miens envirun 

	-----Original Message----- 
	From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Richard Zander 
	Sent: Sun 28-Oct-07 7:48 AM 
	To: Richard Pyle; taxacom at mailman.nhm.ku.edu 
	Subject: Re: [Taxacom] The difference

	Rich:  Thanks for the follow up. I do think that the author of every paper that analyzes a combined morphology and molecular data set does make a decision on the number of apomorphic shared DNA bases implied by a shared apomorphic morphological trait, namely one. This could be wrong by two orders of magnitude. Even if a shared morphological trait were recognized as a surrogate for, say,only  10 shared molecular traits, the fabric of modern phylogenetic classification would necessarily change.
	1. Combined data sets would suddenly not swamp the morphological component,
	and if the data sets were not combined, then
	2. morphological data sets would suddenly have high bootstraps and maybe statistically certain BPPs on branch arrangements.
	(Remember when "optimality alone" of morphological data sets was in vogue as justification for using cladograms in classification? Maybe we are back to puzzling over morphological cladograms.)

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