[Taxacom] Bye bye Crustacea

[Bob Mesibov]

Tonight I was pointed at

Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences
Jerome C. Regier, Jeffrey W. Shultz, Andreas Zwick, April Hussey, Bernard Ball, Regina Wetzer, Joel W. Martin & Clifford W. Cunningham
Nature (Letter) 463 (25 Feb 2010) 1079-1083 (doi:10.1038/nature08742)

What's revealed, among other things, is that Hexapoda nests within Pancrustacea and is sister to Remipedia+Cephalocarida. The tree was built using 62 single-copy nuclear protein-coding genes, which partly explains why it differs from earlier arthropod trees based on nuclear rRNA. Taxon sampling was pretty light (75 arthropods out of how many?) but well-spread.

There are a lot of questions raised by this study, quite apart from the paraphyly issues. Morphologically I find the proposed sister-group relationship for hexapods utterly baffling, but the authors are very sympathetic to my confusion and say

"In conclusion, our phylogenomic study provides a strongly supported phylogenetic framework for the arthropods, but the problem of reconstructing and interpreting morphological evolution within this diverse group remains."

Which might be understood as:

"This is what probably happened. If your morphological studies don't support this framework, you need to do more work on your morphology."

Ummm...
-- 
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery, and
School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
03 64371195; 61 3 64371195
Webpage: http://www.qvmag.tas.gov.au/?articleID=570