Monday, September 24, 2012

Friday, September 21, 2012

Wednesday, September 19, 2012

Snakes, An Origin Story

Quite honestly, I should have been reading a plant paper for my upcoming lab meeting. But then I stumbled across a really cool snake paper and, well, that won out. I regret nothing. As with most people, I will most likely read the plant paper right before the meeting anyway.

A paper published online today in Biology Letters takes a look at the phylogeny of squamate reptiles (lizards and snakes). This group of reptiles is one of the most diverse and well-known vertebrate groups including approximately 9000 species among 61 families. As with many groups, taxonomists and geneticists are trying to reconcile morphology and molecular analysis. This paper is taking the molecular approach, specifically looking at sister groups and interrelationships of major snake clades and iguanian families. Being a well-studied group, molecular analyses have been conducted in the past. These studies have suggested that squamate molecular phylogeny results differ quite a bit from morphological ones. This study takes one gigantic step forward, increasing the sampling of taxa dramatically and doubling the number of genes studied.

The researchers sampled 161 squamate species and 10 outgroup taxa, including mammals (Homo, Mus, Tachyglossus), crocodilians (Alligator, Crocodylus), birds (Dromaius, Gallus), turtles (Chelydra, Podocnemis) and a rhyncocephalian (Sphenodon). Then they sequenced portions of 44 nuclear genes, targeting single-copy genes evolving at appropriate rates. The nucleotide sequences were then translated into amino acids to aid alignment. This alignment consisted of 33,717 base pairs! I’m not going to go into all of the bootstrapping, likelihoods, and Bayesian analyses that were used (even the word Bayesian makes my brain shut down in protest). But suffice it to say that the different analysis techniques that were used yielded similar phylogenies, providing strong support for the relationships found.

The results of this molecular analysis were found to be consistent with other, recent, similar studies. However, there were some interesting relationships discovered. The first of these was that dibamid (legless lizards found in tropical forests) and gekkotans (geckos and the limbless Pygopodidae) are together the sister group to all other squamates. They also found strong support for paraphyly of scolecophidian snakes (blind snakes). Scolecophidians have reduced eyes and are specialized burrowers. Considering these traits, the paraphyly of this group suggests that it is the ancestral form, that other snakes may have been burrowers ancestrally. This makes sense if you compare the morphology of snakes to other burrowing species such as limb-reduced lizards. They both have short tails and elongate trunks. Very good for tunneling their way through the earth.

Overall, a really interesting study that was huge in its scope. I look forward to more of these kinds of studies in the future.

ResearchBlogging.orgJohn J. Wiens, Carl R. Hutter, Daniel G. Mulcahy, Brice P. Noonan, Ted M. Townsend, Jack W. Sites Jr., & Tod W. Reeder (2012). Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species Biology Letters, 4 (11) DOI: 10.1098/rsbl.2012.0703

If you are a non-scientist and I used too many biology-jargony words for you or you just need a refresher on phylogeny, then I recommend looking through these sites:
Fullerton’s Biology 261 course page on Interpreting Cladograms
Berkeley’s Understanding Evolution page on reading phylogenetic trees

Here is some more information on blind snakes:
ScienceBlogs article Scolecophidians: seriously strange serpents

ScienceShot article: Snakes' Slitherin' Subterranean Kin

(images from  Encyclopedia of Life and Neoseeker, respectively)

Monday, September 10, 2012

Curiosity Hot Wheels

NASA's Curiosity rover is soon to become the latest Hot Wheels toy. Mattel, Inc., maker of Hot Wheels, is set to make a 1:64 scale miniature of the "Mars Rover Curiosity" as part of an assortment of 247 toy cars for 2012. The toy's product description says that "Curiosity carries many tools such as a drill, cameras and a laser. Its mission [is] to see if Mars could have ever supported small life forms called microbes... or if humans could explore there some day!

This isn't the first time that Mattel has teamed up with NASA to bring sciency toys to the playroom. Fifteen years ago, Mattel worked with NASA's Jet Propulsion Laboratory (JPL) and the California Institute of Technology (CalTech) to produce the "JPL Sojourner Mars Rover Action Pack Set," a miniature of Curiosity's much smaller, much older cousin, the Sojourner rover which landed as part of NASA's Mars Pathfinder mission on July 4, 1997. Unlike the new Curiosity set, this "Action Pack" came with three miniatures - the rover, its lander and spacecraft cruise stage. The Sojourner action pack quickly sold out, to the point that Mattel reissued it a few times and even released a celebratory 24-karat gold plated version. After this huge success, Mattel brought out a pack recreating the Jupiter-orbiting Galileo probe, followed by a set for the Apollo moon landings, John Glenn's space shuttle mission in 1998, and finally a pack that included scale models of NASA's Mars Climate Orbiter, Deep Space 2 Microprobe and Mars Polar Lander. Even those those Mars spacecraft failed, the toy set sold. Since this last release in 1999, Hot Wheels has not released any NASA mission toys. Even for the highly successful Spirit and Opportunity rovers (although these were released by LEGO and other toy companies).

Want even more Curiosity to play with? NASA has partnered with Microsoft to release an Xbox 360 video game that puts the player in control of the rover's landing. They have also introduced an Apple iPad app where a player can use augmented reality to access a virtual, 3-D Curiosity model.

Who says science isn't fun? I'm seeing some good gift opportunities here!

(via and collectSPACE)
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