January 29, 2010
A nice example of convergent evolution has been published in the latest issue of Current Biology, with two studies showing that echolocation abilities of bats and dolphins have the same underlying genetic basis.
Convergent evolution is where two species independently acquire the same trait in response to similar evolutionary pressures. There are a huge number of examples – venom production in reptiles and mammals, bioluminscence in glow-worms and jellyfish, flightless in numerous different bird species, to name a few. Most examples of convergent evolution are the result of a different means producing a very similar looking end – different structures may be co-opted for the same purpose, or different changes at the genetic level might produce similar phenotypes.
Whats really unusual about the bat/dolphin story is that, not only have they independently acquired echolocation, but that the underlying molecular basis for how they acquired it is almost exactly the same – ie the same changes in the same protein look to have occurred independently in the two lineages. The protein involved is Prestin, which is involved in detection of high-frequency echos rather than production of the sonar. Obviously bats and dolphins are not particularly closely related as mammals go, but if you draw an evolutionary tree of their Prestin sequences, they look like each others closest relatives. The odds of this many identical changes to a protein happening independently in two separate lineages by chance are extremely slim, suggesting there are a very limited number of ways that Prestin can be changed to detect high-frequency sounds, and that selection has played an important role.
As always, Not Exactly Rocket Science has an excellent write up of the two papers, so I suggest you head over there for the details.
The papers are:
Liu et al. Convergent sequence evolution between echolocating bats and dolphins. Current Biology vol. 20, p 53.
Li et al. The Hearing Gene Prestin Unites Echolocating Bats and Whales. Current Biology vol 20, p 55.
January 26, 2010
I just discovered a blog carnival some of you might be interested in. The Carnival of Evolution is out monthly and collects some of the most interesting posts on evolution from throughout the blogosphere. January’s edition was hosted by Observations of a Nerd, and submissions are currently being sought for February’s edition (out on Feb 1st at Skeptic Wonder).
In other blogging news, you may have noticed that some of my posts have the Research blogging icon – the green tick – on them (and if you’re reading this on Sciblogs, many of the other bloggers use this too). This indicates that I’m blogging about published, peer-reviewed research and the post also appears on the Researchblogging.org website. Researchblogging.org collects posts from over 1000 different blogs so is a great place to go to read about published research that might not otherwise make its way out of the scientific literature.
Anyway, Researchblogging.org is now giving out awards (and cash!) to celebrate the best in research blogging – there are all sorts of categories, including best biology blog, best blog post, and best research twitterer. So head over there and nominate your favourite research blog (hint hint!).
January 15, 2010
Hot on the heels of Forest and Bird’s “Bird of the year” competition comes the NZ Plant Conservation Network‘s 2009 favourite plant poll. The winner was announced just before Christmas but I must have missed it in the Christmas rush. While voters in the bird of the year poll managed to display a stunning lack of originality in picking kiwi as their favourite, plant of the year voters were somewhat more creative, voting Pingao as their favourite native plant for 2009.
Pingao (Desmoschoenus spiralis, or the golden sand sedge) plays an important role in stabilizing sand dunes so its likely to become increasingly important in the face of climate change. Who’d have thought it has so many fans? The shadowy and mysterious Pingao Pressure Group was obviously busy lobbying for votes while Pohutukawa advocates were looking the other way.
Here’s a picture:
(Photo by John Sawyer, NZ Plant Conservation Network)
Others in the top ten include the tree nettle (Ongaonga) at number 2, Chatham Island speargrass, some traditional favourites like Southern rata, Chatham Island forget-me-not and Kakabeak, and the plant with the best name of all, the fish-guts plant.
January 14, 2010
An upcoming issue of PNAS has a special supplement on evolutionary medicine, with articles arising from the Arthur Sackler Colloquium on “Evolution in Health and Medicine” that was held last year.
Evolutionary medicine is a relatively newly recognised field that applies the principles of evolutionary biology to understanding health and disease. But medical science has in fact been making use of evolutionary biology for a long time – our understanding of things like viral transmission between species, antibiotic resistance, and geographic differences in disease susceptibility are all fundamentally based on evolutionary principles. The applications of evolutionary biology to medicine are increasing, as shown by the diverse topics covered in the colloquium.
An article by co-authored by several leading researchers in evolutionary medicine, including Randolph Nesse, Carl Bergstrom and our own Peter Gluckman is particularly interesting – making the case that evolutionary biology is a crucial basic science for medicine that should be taught to all medical students. Nesse and colleagues point out that, not only are there direct applications of evolution to medicine, but that the principles of evolution apply to every biological system and level, providing a “unifying framework for interpreting biological phenomena”. Read the rest of this entry »
January 8, 2010
Nick Veasey likes to X-ray things. Big things, like buses and jumbo jets, and small things like leaves and feathers. And then he turns them into fantastic art pieces.
This video from www.ted.com has some great images, so I thought I’d share it with you – who’d have thought X-ray could be so artistic?
Toiling over 14-inch sheets of X-ray film in a hangar in Kent, photographer Nick Veasey has revealed the shadowy interiors of objects as diverse as vacuum tubes, bulldozers, jet airliners — even fresh cadavers. By his own estimates, he’s photographed thousands of everyday items, often arranging them into tableaux that are at the same time familiar and luminously alien. They reveal surprising details and prove that items have an inner beauty.
January 6, 2010
As a geneticist, I’m only rarely let out of the lab to chase after my study animal, the tuatara. I count these occasions as a gift, where I get to feel like a “real” biologist and learn to talk knowledgably about the ecology and habits of tuatara (which, lets face it, are generally of more interest to the lay person than their genes). I also count myself lucky that I’ve never been bitten by a tuatara – although I have helped extract other people’s fingers from the mouths of tuatara and can confirm that it is an eye-watering experience.
We now know exactly how hard a tuatara can bite, thanks to a recent study published in the Journal of the Royal Society of New Zealand. Marc Jones (University College London) and Kristopher Lappin (California State Polytechnic University) have measured bite force in adult tuatara and found that a male tuatara could produce a bite force of up to 238 Newtons. Jones and Lappin measured bite force using a custom-designed isometric force transducer. They report that the tuatara needed little encouragement to bite onto the leather-covered bite plates, and that “once biting commenced the tuatara would maintain its grip with considerable reluctance to release”. Something that will come as no surprise to those who have been on the receiving end of a tuatara bite! Read the rest of this entry »