New books on evolution and vertebrates

November 27, 2010 • 10:29 pm

by Greg Mayer

Three new (or newish) books have come my way that may be of interest to WEIT readers.

First, my friend and colleague Jonathan Losos has edited a collection of essays entitled In the Light of Evolution: Essays from the Laboratory and Field. I’d mentioned his book about the world’s best animals, anoles, in a post last year. The new book features mostly chapters by scientists about the actual experience of carrying out research, and why they think it’s cool (NB: it doesn’t involve rock stars). Ted Daeschler and Neil Shubin, for example, relate their motivation and experiences in traveling to the Canadian Arctic in search of transitional tetrapods.  It’s aimed at a general reader or student audience, and thus might be of interest to a number of our non-specialist readers. I haven’t finished reading it yet, and hope to give a more complete report during Jerry’s next peregrination.

I’ve also just received a copy of How Vertebrates Left the Water by Michel Laurin, a famed Canadian paleontologist at the Muséum National d’Histoire Naturelle in Paris. The book is largely a translation (by Laurin himself) of his earlier Systématique, Paléontologie et Biologie Évolutive Moderne: l’exemple de la sortie des eaux chez les vertébrés (Ellipses éditions, Paris, 2008), with the text and bibliography updated. The book covers a lot of the same (muddy) ground that Neil Shubin’s Your Inner Fish does, although at a somewhat more technical and narrower level (sorry– couldn’t resist the allusion to coming ashore!).

And finally, not so new, is Bob Carroll‘s The Rise of the Amphibians, published in 2009, and which I got a copy of last year. Carroll is the dean of North American paleontology, and Laurin studied with him at McGill. Carroll’s book covers all of amphibian history, from their origins (the focus of Laurin’s book) to today. Although it has a predictably strong emphasis on the fossil record, he even includes a chapter on the  amphibian conservation crisis of today. Because reptiles (amniotes) descend from amphibians, this transition is covered as well. This book is the least likely of the three for casual bedtime reading, but it is well written, profusely illustrated, and has 16 attractive color plates.

The beakiest bird

November 27, 2010 • 10:24 am

I photographed a specimen of the South American sword-billed hummingbird, Ensifera ensifera, in the bird collection at the Universidad de Los Andes, using a pen for scale. The bird is found throughout the northern Andes, and is the only species in the genus Ensifera.

Most important, it’s the only living bird whose beak (3.5 to 4 inches long) is longer than the rest of its body (ca. 2-3 inches)!

Here’s a skeleton of the bird, showing how disproportionately long the bill is.  Wikipedia reports (and there’s verification in a video below) “since the Sword-billed Hummingbird’s beak is very long, it grooms itself with its feet”.

You’ve certainly guessed that the long bill is an adaptation for feeding.  These birds feed largely on passionflowers (Passiflora), which have long corolla tubes that contain the nectar.  The birds approach these pendant flowers from below, deftly inserting their beak like so [note: as several alert commenters note below, the flower shown is not Passiflora but Brugmansia]:

The paper by Lindberg and Olesen (citation below) strongly suggests that these birds are also important pollinators of Passiflora, since they carry pollen on their beaks from flower to flower.  But the authors also warn that their specialization on one genus of flower, and the increasing habitat fragmentation in the Andes, may put these birds on the verge of extinction.

There are some lovely videos and photos of this bird at The Internet IBC bird collection, including a female supping from a feeder and another female using her feet to groom herself.  Arkive has another grooming video and a marvelous video of feeding from a Passiflora.

Hummingbirds are truly the jewels of the avian world, and display some of the most remarkable adaptations seen in animals.  I am always amazed at seeing how these birds hover, absolutely rock still, while they feed.  No helicopter is as agile.  And how some of these nectar-guzzling species make a 600-mile nonstop journey across the Gulf of Mexico—20 hours of straight flight—is beyond belief.

Here are a few words, and some dramatic videos, about how the PBS film “Hummingbirds” was made (I haven’t seen it).

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Lindberg, A. B. and J. M. Olesen. 2001.  The fragility of extreme specialization: Passiflora mixta and its pollinating hummingbird Ensifera ensifera. Journal of Tropical Ecology 17: 323-329.

Reports: Blair-Hitchens debate

November 27, 2010 • 6:57 am

UPDATE:  As James Cameron reports in the comments below, the full transcript of the debate is online here (note that there are three parts).

Associated Press (the most thorough report):

“Is it good for the world to worship a deity that takes sides in wars and human affairs, to appeal to our fear and to our guilt – is it good for the world?” Hitchens said in his opening remarks.

“To terrify children with the image of hell … to consider women an inferior creation. Is that good for the world?” Hitchens asked as he opened the debate hosted by the Munk Debates center.

Though his face was pale and drawn, and his trademark mop of unruly hair gone, he was no less animated than usual in spite of his battle with cancer of the esophagus. He said earlier Friday that he scheduled his chemotherapy treatments around the debate so he “wouldn’t have to let anyone down,”

“This is what I do whether I’m sick or not. (Religion) is still the main argument,” said Hitchens who has made it known that his diagnosis has not opened him to God or religious belief.

The Guardian:

Both men were unabashedly stalwart in their positions. Hitchens, one of the leading “new atheists” and author of the hit book God Is Not Great, slammed religion as nothing more than supernatural gobbledegook that caused untold misery throughout human history. “Once you assume a creator and a plan it make us subjects in a cruel experiment,” Hitchens said before causing widespread laughter by comparing God to “a kind of divine North Korea”.

Blair, perhaps not surprisingly, was a little less forthright. On the backfoot for much of the debate he kept returning to his theme that many religious people all over the world were engaged in great and good works. They did that because of their faith, he argued, and to slam all religious people as ignorant or evil was plain wrong. “The proposition that religion is unadulterated poison is unsustainable,” he said. Blair called religion at its best “a benign progressive framework by which to live our lives”.

Throughout the 90-minute debate Hitchens seemed to have the crowd’s sympathy. That might have been to do with his ill appearance due to cancer, but was far more likely to be down to the sharpness of his verbal barbs and the fact that 57% of the audience already agreed with his sceptical position according to a pre-debate poll, while just 22% agreed with Blair’s side. The rest were undecided.

57% of the audience agreed with Hitchens beforehand! Well, maybe the debate drew a biased sample, but I still find that amazing—and heartening!

And here’s a New Year’s present: the AP reports that “BBC World News and the News Channel will broadcast the debate on Jan., 1 2011.”

The Winnipeg Free Press:

Preliminary results posted on the Munk Debates website from an audience poll suggest Hitchens won the debate, with 68 per cent of those who handed in a ballot at the end of the night saying they favoured the con side and 32 per cent agreeing with Blair.

Both, however, seemed to sway many people to their way of thinking, as ballots submitted before the debate put the audience of 2,700 at 57 per cent con, 22 per cent pro and 21 per cent undecided.  .  .

Hitchens, a columnist for Vanity Fair and author of “God is not Great: How Religion Poisons Everything,” said for religion to be a force for good it would have to first give up all supernatural claims. He proposed a “pact with the faithful.”

“As long as you don’t want your religion taught to my children in school, given a government subsidy, imposed on me by violence, any of these things — you are fine by me,” he said.

Caturday felid: cat lapping!

November 27, 2010 • 6:23 am

Any ailurophile who’s at all internet literate knows that four scientists have just solved the age-old problem of “how do cats drink”?  This is one of those cool cases where a simple problem has been ignored because it’s not considered scientifically sophisticated—even if that problem has a relatively simple solution.  The solution is published in this week’s Science, which has a nice cover.

The title of the papers is succinct: “How cats lap: water uptake by Felis catus.” (I would have used just the first three words; the second part is redundant.)

Like most other people, I’d always thought that cats curled their tongues backwards when they drink, forming a little cup to convey liquid to the mouth.  The new work shows that this is wrong.  Here’s the abstract with the TRUTH:

Abstract. Animals have developed a range of drinking strategies depending on physiological and environmental constraints. Vertebrates with incomplete cheeks use their tongue to drink; the most common example is the lapping of cats and dogs. We show that the domestic cat (Felis catus) laps by a subtle mechanism based on water adhesion to the dorsal side of the tongue. A combined experimental and theoretical analysis reveals that Felis catus exploits fluid inertia to defeat gravity and pull liquid into the mouth. This competition between inertia and gravity sets the lapping frequency and yields a prediction for the dependence of frequency on animal mass. Measurements of lapping frequency across the family Felidae support this prediction, which suggests that the lapping mechanism is conserved among felines.

Translation: the cat curls the tip of its tongue “downward” a bit,  touches it to the surface of the liquid, then quickly draws its tongue upward.  The inertia produces a column of liquid which the cat then “bites off” and holds it in cavities in its mouth, until it swallows the liquid—every 3 to 17 laps, according to the authors.

And I want to put in the first paragraph because it’s informative and also a pretty good model of clear scientific writing:

Terrestrial animals have evolved diverse means to acquire water, including absorption through the skin (1) or extraction of moisture from food (2), but most rely on drinking (3–12). Drinking presents a challenge to land vertebrates, because fresh water occurs mainly as horizontal liquid surfaces, such as puddles, ponds, lakes, or streams, and animals must displace water upward against gravity to drink it. Crucial in the drinking process is the role of the tongue, which in vertebrates is used in two distinctly different ways.  Vertebrates with complete cheeks, such as pigs, sheep, and horses, use suction to draw liquid upward and use their tongue to transport it intraorally (13, 14). In contrast, vertebrates with incomplete cheeks, including most carnivores, are unable (after weaning) to seal their mouth cavity to generate suction and must rely on their tongue to move water into the mouth (13). When the tongue sweeps the bottom of a shallow puddle, the process is called licking (4). When the puddle is deeper than the tongue excursion into the liquid, it is called lapping (15). Here, we report on the lapping mechanism of the domestic cat (Felis catus).

Ed Yong’s take is at Not Exactly Rocket Science, and there’s no need for me to repeat what he said.

Here are some photos from the paper showing how the tongue forms the liquid column (below is the caption from the paper):

The lapping process. (A to F [“C” is below]) Snapshots showing the movement of the tongue of F. catus and the dynamics of the liquid column during a lapping cycle. Lapping occurs by fluid adhesion to the dorsal part of the tongue’s tip and by lifting a liquid column through the tongue’s upward motion, before jaw closure. Time elapsed from the first frame is given in the top left corner of each frame.

Another photo from the paper.  Note that the part of the tongue that the cat uses for lapping (the front part) is free from papillae.   Presumably these would somehow inhibit lapping, but the rougher parts of the tongue are of course necessary for grooming and are also used for eating (bigger cats use the papillae to scrape flesh from bones).

(G) Photograph of the dorsal side of the tongue of F. catus, acquired under anesthesia (16). Only the smooth tip is used in lapping.

Here are three short supplemental movies from the paper, two showing an “artificial tongue” used to calculate the physics of the process (captions taken from the paper).

Cat lapping. Three lapping events of an adult domestic cat, during its normal drinking process. The video was recorded with a Sony HDR-SR5 camera operated at 120 frames/s and is here shown at 30 fps (i.e., slowed down four times). As the tip of the tongue comes in contact with the liquid surface, water adheres to the dorsal side of the tongue’s tip. A liquid column forms when the tongue is rapidly lifted. The liquid column grows by inertia, until gravity induces its break-up through pinch-off. Jaw closure results in the capture and ingestion of part of this column. The lapping frequency can be calculated from the number of laps in the video.

Artificial cat tongue 1. Physical model of a cat lapping. The physical experiments consisted of lifting a glass disk from the surface of water. The disk was initially in contact with the free surface of a water bath and was moved upward by a motorized linear stage, FiSER (Filament Stretching Rheometer). As the disk moved upward, the liquid column was imaged from the side with a high-speed digital camera (Phantom V5) at 1000 frames/s and is here shown at 15 frames/s (i.e., slowed down 67 times). In Movie S2, The physical parameters were R =12.7 mm, H = 30 mm, UMAX = 50 cm/s, where R is the radius of the disk, H is the maximum height of travel, and UMAX is the maximum speed attained. In Movie S3, the physical parameters closely match those of the domestic cat: R = 5 mm, H = 30 mm, and UMAX = 74 cm/s.

Artificial cat tongue 2. (see description just above).

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Reis, P. M., S. Jung, J. Aristoff, and R. Stocker, 2010.  How cats lap: water uptake by Felis catus. Science 330:1231-1234.

Smackdown!: Blair vs. Hitchens

November 26, 2010 • 11:49 am

We all know that Tony Blair and Christopher Hitchens are debating the question “Be it resolved that religion is a force for good in the world” in Toronto tonight; the action starts at 7 pm EST.  If you want to watch it live, and have five bucks Canadian to spare, you can sign up to buy a live stream here.  (Look at it this way: it’s cheaper than pay-per-view sports but infinitely more entertaining.)

But I suspect it’ll all be on YouTube soon.

The surreal treehoppers

November 26, 2010 • 8:00 am

Last week’s Nature highlighted the sculptures of Alfred Keller (1902-1955), and the example, a model of the Brazilian treehopper Bocydium globulare, struck me as one of the weirdest animals I’ve ever seen:

Martin Kemp describes Keller’s work:

Keller was trained as a kunstschmied, an ‘art blacksmith’. From 1930 until his early death he was employed by the Berlin Museum für Naturkunde (Museum of Natural History), painstakingly labouring over his recreations of insects and their larvae. Each took a year to complete. Keller worked first in plasticine, from which he cast a model in plaster. This plaster reference model he then recast in papier maché. Some details he added, cast in wax, with wings and bristles in celluloid and galalith (an early plastic material used in jewellery). Finally he coloured the surfaces, sometimes with additional gilding. The levels of patience and manual control Keller exercised were incredible. His fly, for example, boasts 2,653 bristles.

. . . Keller was a sculptor of monumental one-off portraits. Each model is a masterpiece, with no effort spared. It is difficult to see how such a skilled artisan could survive in today’s museums, with their emphasis on cost analysis. Keller’s exacting models may be things of the past, yet they are far from obsolete. Like the great habitat dioramas, they exercise a magnetic attraction.

The first thing a biologist does on seeing a model like this is think, “This can’t be real,” and resorts to some Googling. Sure enough, it’s a real insect.  Here are two photos by Patrick Landmann (check out his other terrific nature photos):

The second thing one asks is, “What the bloody hell is all that ornamentation on the thorax?” (Note that the “balls” on the antenna-like structure aren’t eyes, but simply spheres of chitin.)  A first guess is that it’s a sexually-selected trait, but those are often limited to males, and these creatures (and the ones below) show the ornaments in both sexes.  Kemp hypothesizes—and this seems quite reasonable—that “the hollow globes, like the remarkable excrescences exhibited by other treehoppers, probably deter predators.”  It would be hard to grab, much less chow down on, a beast with all those spines and excrescences.

Note, though, that the ornament sports many bristles.  If these are sensory bristles, and not just deterrents to predation or irritating spines, then the ornament may have an unknown tactile function.

Membracids, related to cicadas, are in the class Insecta (insects, of course), the order Hemiptera (“true bugs”) and the family Membracidae.  Like aphids, which are also “true bugs,” adult and immature treehoppers feed on plant sap.

For a wonderful panoply of membracid photos, download this pdf file. Here are some of the images, showing that, as Kipling said, “The wildest dreams of Kew are the facts of Khatmandu.” If Dali invented insects, they’d look like these (all photos by Patrick Landmann):

The color and shape of this last one makes me suspect that it’s mimicking a wasp:

h/t: Matthew Cobb

After the fact

November 26, 2010 • 6:56 am

I couldn’t resist posting this delightful Thanksgiving greeting produced yesterday by Doc Bill and his kitteh “Kink.”  (Click to enlarge.)  Doc is dead certain that Kink is going to win our contest, but the competition is stiff: we have over 30 entries now. Be sure to get yours in before December 1. Even if you’re not one of the three winners, there’s a good chance that your cat will appear here some time in the future. There are too many awesome photos and stories to limit them to three.