Archive for June, 2006

Vagaries of the Genetic Record

29 June 2006

Figure by Nishahara et al. 2006

In case you missed it, a clade was born on June 19th in an online version of an article published in the June 27th issue of PNAS. The superordinal group is christened “Pegasoferae”, and true to the name it links the hand-winged (Chiroptera) bats and the odd-toed (Perrissodactyla) horses/tapirs/rhinos along with the meat-hungry Carnivora. Evidence for the revised phylogeny comes from the analysis of retrotransposons the curious wandering signifiers of genetic codes.

This marks the latest in a series of marked collisions between long-standing fossil and morphological-based mammal phylogenies and the forest of evolutionary trees offered up by the new genetics. An earlier reconfiguration involved whales, hippos and mesonychids and birthed the whale/even-toed: Cetartiodactyla. It’s another story.

Another new DNA-inspired clade is the more controversial Afrotheria, which, you’ll notice, sits at the bottom of that stack, save the backwards bagged ones.

The advent of Pegasoferae also marks the final end of the once revered order Ungulata, the hoofed-mammals. Horses and cows are now split by bats and cats.

2300 years after Aristotle, 300 years after Carolus and we’re still arguing about the arrangement of large pieces of the busty and hairy class mammalia. In fact if anything matters have become more convoluted since Linnaeus with the advent of DNA sequencing. We still navigate the murky waters by his compass now bloated into a large desktop model.

Red Queen Revisited.

11 June 2006

Still running to stand still. A number of wonderous and strange "science stories" have been popping up: tales of insular dwarf dinosaurs, red rain carrying extraterrestrial microbes, and the rediscovery the world's most-appendaged millepede after an 80 year hiatus.

The new mini-sauropod is named Europasaurus:

Figure by Octavio Mateus.

The abstract is at Nature. Some had claimed the miniature dinosaur bones, some of which were found in Germany in the 19th century, might have belonged to a juvenile sauropod. Histologic studies show that they actually come from small-bodied adults who may have shrunk in response to limited island resources, a mechanism proposed for dwarf Mammoths found on the Channel Islands of Califorina for the recently described toy-breed hominid Homo floresiensis from the Indonesian island of Flores. Afarensis has a detailed analysis in two posts.

The purportedly panspermic monsoons hit India back in 2001. At 500x the replicating "cell-like" structures found in the rain look like this:

Photography by Godfrey Louis.

The story comes from an article published in the Springer journal Astrophysics and Space Science with the eyebrow lifting title "The Red Rain Phenomenon of Kerala and its Possible Extraterrestrial Origin". Among other claims, the "exobes" reportedly lack DNA and are capable of thriving at temperatures as high as 600˚ F. The authors, Godfrey Louis and A. Santhosh Kumar, write like pure and/or applied physicists, not micro- or "astro"biologists and ultimately hedge their claim,

In the context of a suspected link between a meteor airburst event and the red rain, the possibility for the extraterrestrial origin of these particles from cometary fragments is discussed (2006).

There is a pretty convincing refutation by Ian Goddard . Goddard cites an official report by the Government of India identifying the unusual red microbes as belonging to a genus of "aerial algae" known as Trentepohlia. If you find all of this rather Fortean, you might be interested to know that Charles Fort himself investigated "red rain" in the early 20th century.

The real astrobiologists are too busy studying terrestrial microbialites, like the 3+ billion-year-old ones featured on the cover of the current and aforementioned issue of Nature:

No reports yet of stromatolites falling from the sky.

Nature is also the place to go to read about Illacme plenipes, recently rediscovered in San Benito county, California.

At 750 legs, this guy almost puts truth to the lie of the "millipede" moniker.


6 June 2006

Jeremy mailed me a copy of An Almanac for Moderns by Donald Culross Peattie. It's a 1980 reprint with an afterword by Lewis Thomas and nice zodiacal engravings by Charles H. Joslin. Funny, I'd just noticed the first buzzing cicadas this weekend, perhaps the early emerger Okanagana?

I biked around trying to get one on record. Eventually, I realized that the clacket of my bike was drowning out the cicada trills. I heard a few when I started walking but in all my videos, they're invariably drowned out on the recordings, by cars, aircraft, mockingbirds. Maybe if you turn the volume all the way up…

Thanks Mr. Helm!


1 June 2006

I suppose the mood here at microecos has been rather bleak, what with all the dying memes, processed food, exiled roosters and disappearing Condors. I’m afraid the next episode of D.B. is unlikely to lift spirts much.

So here is a much needed injection of cuteness, courtesy of the Praying Mantis hatch which graced my window last Friday morning (just try to ignore the dying cycad):

The tragic bits have been edited out, and saved for later.