Sunday, September 27, 2009

Last week in the world of science

There were a number of interesting papers published in the scientific literature last week. Here's a brief recap of those I found interesting:

Novo et al. 2009. Eukaryote-to-eukaryote gene transfer events revealed by the genome sequence of the wine yeast Saccharomyces cerevisiae EC1118. PNAS 106:16333-16338.

Gene transfer is extremely common in prokaryotes, but it's fairly rare in eukaryotes. Novo et al. sequenced the genome of S. cerevisiae EC1118 and found three regions totalling 120 kb of DNA that had been transfered in from at least two other yeast species. These weren't just transposable elements, but contained some genes used the winemaking process. As I said, this kind of transfer of metabolically-useful genes is common in bacteria but not well-known in eukaryotes. I wonder if this is also common in eukaryotes, but we just haven't noticed it? It certainly raises the question of how these genes get transfered.

Spaulding et al. 2009. Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution. PLoS ONE 4(9):e7062.

This is a further examination of whale phylogeny using a broader taxon sampling and new sequence information. Of particular interest here is the relationship of the Mesonychians and the raoellid Indohyus to cetaceans. Spaulding et al. essentially found this question unresolvable. Their most parsimonious trees place Indoyus as sister to the cetaceans and Mesonychians as sister to all the artiodactyls (including whales). One tree two steps longer than the MPTs puts the Mesonychians as sister to the cetaceans.

Hu et al. 2009. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus. Nature 461: doi:10.1038/nature08322.

A PDF pre-print of this paper was rather unceremoniously dumped on the Nature website at the end of the week. This is not surprising, given the content. I used to shrug off the feathered dinosaurs as merely interesting but not very good intermediate forms. They possess traits that appear intermediate between dinos and birds, but they appear in the fossil record "after" Archaeopteryx, a much more bird-like animal. The feathered dinos are morphological but not stratigraphic intermediates. Well, so much for that. Hu et al. have found a feathered dino that "precedes" Archaeopteryx in the fossil record. That makes the new fossil Anchiornis a morphological and stratigraphic intermediate (a stratomorphic intermediate). I can't say I'm terribly surprised though. (I'm certain some creationists will denounce it as not really feathered. Denunciation doesn't really accomplish much in this case, but there it is.)

Hales et al. 2009. Topographic and ecologic controls on root reinforcement. Journal of Geophysical Research 114:F03013.

From the completely random file: Hales et al. found that Appalachian slopes dominated by rhododendrons make better candidates for landslides than slopes with a mix of native trees. That's just a point of local interest. If you're not from around here, you probably don't care.