30 November 2006

It was raining mussels and clams

"During a cloudburst hundreds of Anodonta anatina (L.) dropped on the pavement out of a rather strange black squall that suddenly appeared over Paderborn" and "in Chester (Pennsylvannia) masses of the tiny Gemma gemma dropped to the ground on June 6th 1869 during a heavy afternoon storm".
Kobelt (1897) cited in Dörge et al. (1999)

Dispersal mechanisms of land snails is one of the recurring subjects on this blog. Previous posts discussed dispersal by birds (here, here), the wind and continental drift, and also Charles Darwin's interest in the subject.

Whenever I find a small colony of a rare species, the first question that usually comes to mind is "How did these snails get here?" And, whenever I am thinking about the distribution patterns of species restricted to specific habitats, such as Gallandia annularis, a related question pops in mind: "How do these snails disperse between suitable habitats?"

A paper I read this week, by Dörge et al.<sup>1, provides a review of several natural and anthropogenic (associated with human activities) passive dispersal mechanisms for land snails. Passive dispersal takes place when snails do not migrate on their own (which would be active dispersal), but are transported by some external agency.

Floods are cited as one natural mechanism that disperses land snails along the floodplains of streams. The authors speculate that modifications of flood plains by humans and the lowering of the intensities of floods by the building of dams may have caused some species that may have relied on floods for dispersal to become rare. As an example, they cite Candidula unifasciata, a rare European species that was apparently once common on floodplains.

One dispersal mechanism that I wasn't aware of is that until methods were introduced to purify plants seeds, land snails were commonly transported mixed with seeds across country borders.

Despite the abundance of, especially anthropogenic, passive transport mechanisms for land snails, the authors, however, caution that "[i]t is unknown, how many of these single long-distance transport events actually lead or have led to the establishment of new populations...Many of the passive transport pathways provide dead ends, because the animals transported end up in unfavorable environments..."

One anthropogenic mechanism discussed in the paper attracted my attention. Land snails, for example, Helicella itala and Pupilla muscorum, have been found attached to the fur of sheep. In Germany, mostly during the 19th century millions of sheep were kept in migratory herds that were annually moved between winter, summer and autumn pastures. Therefore, it is speculated certain land snail species may have been dispersed by the migrating sheep herds.

When I was reading about sheep-mediated dispersal, I immediately thought of the goats that we frequently encounter on Turkish mountains. Although I don't think there are migratory herds of goats moved between vastly separated regions of Turkey, some local herds may cover significant distances over one mountain or mountain chains. And, if snails do attach to their bodies, they may have been responsible for the dispersal of some mountain species, such as Gallandia annularis. The next time we encounter goats in Turkey I will try to come up with a way to examine some of them for possible snails.

1. Dörge et al. 1999. The significance of passive transport for dispersal in terrestrial snails (Gastropoda, Pulmonata). Zeitschrift für Ökologie und Naturschutz 8:1-10.

29 November 2006

Predators and natural selection in lizards

"Evolutionary biology is by its nature an historical science, but the combination of microevolutionary experimentation and macroevolutionary historical analysis can provide a rich understanding about the genesis of biological diversity."
Losos et al.1

Anolis sagrei is a common Caribbean lizard that is often found on the ground in the absence of terrestrial predators, but begins to spend more time on trees when a larger and entirely terrestrial predatory lizard, Leiocephalus carinatus, invades its territory.

A recent paper by Losos et al.1 demonstrates how natural selection driven by predators can influence prey phenotype over a short period of only a year, or within a single generation.

The authors introduced L. carinatus to six small Bahamian islands that naturally contained A. sagrei and as controls, chose six other islands that had A. sagrei without the predator. They predicted that: (1) initially when A. sagrei spent most of its time on the ground, individuals with relatively longer legs, being faster, would be better able to elude the predators; (2) gradually, in the presence of the predator A. sagrei would become more arboreal; (3) as A. sagrei became more arboreal, those with shorter limbs, being better able to move on tree trunks, would be selected.

The results, only after a year, confirmed their predictions. For example, as shown in the figure below, the lizards on the islands with introduced predators (filled symbols) became more arboreal, while the habitat preferences of those on control islands (open symbols) remained unchanged.

Moreover, on islands with introduced predators the lengths of the hind legs2 of A. sagrei changed as predicted as the numbers extracted from Table S1 in the supplement to the paper show:

Died (1st 6 months): 0.82
Lived (1st 6 months): 1.48
Died (2nd 6 months): 2.44
Lived (12 months): -0.06

What happened was that during the first 6 months when most A. sagrei were still on the ground, those with relatively longer hindlegs were better able to escape from the predators, but during the next 6 months after they started moving up the trees, the situation was reversed and individuals with relatively shorter hindlegs were better able to survive. As the authors note, the direction of natural selection, first favoring longer and then shorter legs, was reversed during the course of one year. This is shown on the next figure.

The magnitude of the selection gradient3 reflects the intensity of selection on hindlimb lengths. The selection gradient is positive for the lizards on the islands with introduced predators (filled symbols) during the first 6 months and then it becomes negative as the direction of natural selection reverses.

It is fascinating that we are now seeing demonstrations of how evolutionary theory can be used to make and test predictions and hypotheses about the course of evolution. This is something no pseudoscientific theory of biological evolution can accomplish.

1. Jonathan B. Losos, Thomas W. Schoener, R. Brian Langerhans, and David A. Spiller. Rapid Temporal Reversal in Predator-Driven Natural Selection. Science 17 November 2006: 1111. Abstract
2. The listed numbers are actually mean relative hindlimb lengths. Relative hindlimb length for a lizard was calculated as the residual of logarithmically transformed hindlimb length versus snout-vent length. Although not stated in the paper, I am assuming that logarithmic transformation was applied to normalize the distributions of lengths and the residuals from the regression of hindlimb length versus snout-vent length were used to correct for the dependence of hindlimb length on overall body size. A negative value for the surviving lizards after 1 year indicates that their hindlimb lengths were mostly below the regression line; in other words, their hindlimbs were getting shorter relative to their body sizes.
3. Selection gradients are coefficients obtained from regression analyses of measured traits (in this case, hindlimb lengths) versus fitness (in this case, defined as whether a lizard survived or died).

28 November 2006

Do you have prosopagnosia?

Prosopagnosia, also called face blindness, is an impairment in the recognition of faces. Measure your ability to recognize faces with these 2 face recognition tests.

I got a score of 82% on the Famous Faces Test and 84% on the Old-New Faces Test (those were some mean-looking ugly women). The average test score is said to be 85%.

Bioblitz revisited

Back in June, I participated in the Potomac Gorge Bioblitz as a member of the mollusk team, survived and later, wrote about it here.

An account of the bioblitz has just been published in the Winter 2006 issue of the Nature Conservancy Magazine. You may read it here. Unfortunately, mollusks did not get any coverage.

27 November 2006

The return of the pseudoscorpions

I find pseudoscorpions most often when I am sorting soil samples for tiny snail shells under a bright light in the lab. They are fascinating creatures and I would love to watch them in their natural surroundings, but their usually dark colored tiny bodies would be very hard to spot on dark soil in dimly lit forests. Moreover, according to Weygoldt1, pseudoscorpions spend most of their lives in small crevices and seldom appear on open ground. I have also occasionally found them in containers of empty snail shells, which indicates that they hide in empty snail shells. The individual pictured here was from a soil sample that I collected last weekend.

This specimen was less than 2 mm long.

Pseudoscorpions made their debut on this blog in a previous post. If I had more time on my hands, I would learn how to identfify them and study their zoogeography.

More information on pseudoscorpions by Mark Harvey, a world authority on them, is available here.

This page has links to images of British pseudoscorpion species and to past issues of Galea, a pseudoscorpion newsletter.

Tree of Life has a list of references on the evolution and phylogeny of Arachnida, the class to which the pseudoscorpions belong.

A primer on pseudoscorpions by Chris Buddle.

1. Peter Weygoldt. 1969. The Biology of Pseudoscorpions. Harvard University Press.

26 November 2006

An operculate snail far from the sea: Hendersonia occulta

Terrestriality, the ability to survive and reproduce on land, has evolved independently several times in gastropods (snails). The close relatives of any group of land snails often reveal clues to where their common ancestors lived. The group of land snails with the most number of species is the pulmonates. Among their close relatives are the snails in the family Ellobiidae that always live by and still reproduce in the sea. One ellobiid snail that I wrote about was Melampus bullaoides. The ellobiids' close association with the sea indicates that the ancestors of pulmonates were marine snails.

Another family of snails that evolved to become terrestrial independently of the pulmonate snails is the Helicinidae. Their present-day distribution includes the subtropical and tropical zones of North and South America, the Indopacific and Pacific islands and some parts of Asia and Australia. The only species that seems to have moved away from the subtropical and tropical zones is the North American Hendersonia occulta. According to Hubricht1, the present range of this species consists of 2 disjunct areas: one in southwestern Wisconsin and northeastern Iowa and the other in the southern Appalachians (Virginia, West Virginia and down to Tennessee.

Hendersonia occulta crawling. Note its single pair of tentacles.

A close inspection of the external anatomy of Hendersonia occulta offers several clues to its evolutionary origins. Perhaps, the easiest to notice of these is its single pair of tentacles like those of marine snails. Another clue, which may require closer inspection with at least a magnifying lens, is the location of its eyes on its head and not on the tips of its tentacles. And finally, the 3rd clue, which is even harder to notice, is that this snail has an operculum that it uses to close its aperture. Unlike the thick and hard operculum of Pomatias elegans, a species representing yet another independently evolved lineage of terrestrial snails, the operculum of Hendersonia occulta is thin and has much less calcium carbonate. Also, Hendersonia occulta can withdraw deep into its shell, which is something Pomatias elegans cannot do, because its inflexible operculum gets stuck at its aperture.

Now, we know that the ancestors of Hendersonia occulta were marine snails. In fact, some of its close relatives still are.

The arrow points at the edge of the operculum of Hendersonia occulta.

The terrestrial pulmonate snails, on the other hand, have all but lost their opercula during their evolution. This vestige from their marine ancestors lingers on in the Ellobiidae: the larvae of at least some species still have opercula, which they lose before turning into adults.

1. Hubricht, L. 1985. The distributions of the native land mollusks of eastern United States Fieldiana #24.

24 November 2006

I am a male! Woo hoo!

The Gender Genie, link via A Snail's Eye View, has correctly figured out my gender as male.

I submitted 2 of my blog posts. The first one, Funeral march for a dead slug, received a Female Score of 273 and a Male Score of 408, while the second one, A lord in Europa Minor, got a Female Score of 424 and a Male Score of 662. The male to female score ratios are 1.49 and 1.56, respectively.

The determination, it seems, is based on the comparing of the frequencies of feminine and masculine "keywords". In both of my sample writings, I use the and are, 2 of the masculine keywords, a lot of times. But, I also use not and with, 2 of the feminine keywords, many times.

If you are having 2nd thoughts about your gender, let the Gender Genie help you out.

More concise facts about me

The one word meme from Abnormal Interests. You can only type one word. No explanations.

1. Yourself: optimist
2. Your boyfriend/girlfriend: history
3. Your hair: messy
4. Your mother: alright
5. Your father: buried
6. Your favorite item: E-500
7. Your dream last night: toe
8. Your favorite drink: ale
9. Your dream car: none
10. The room you are in: basement
11. Your ex: none
12. Your fear: loneliness
13. What you want to be in 10 years: busy
14. Who did you hang out with last night? family
15. What you're not? religious
16. Muffins: nuts
17. One of your wish list items: ipod
18. Time: a-changing
19. The last thing you did: breakfast
20. What you are wearing: comfortable
21. Your favorite weather: hot
22. Your favorite book: burned
23. The last thing you ate: cake
24. Your life: scientific
25. Your mood: good
26. Your best friend: Nicole
27. What are you thinking about right now? nothing
28. Your car: noisy
29. What are you doing at the moment? living
30. Your summer: fun
31. Your relationship status: married
32. What is on your TV? dust
33. What is the weather like? sunny
34. When is the last time you laughed? lastnite

21 November 2006

The naughty bit of a snail

The ruler is in millimeters. The verge is about 3 mm long. (e: epiphallus, v.d.: vas deferens.)

This is the inside of the penis of a specimen of Xerocrassa cretica, a land snail in the family Hygromiidae that lives in western Turkey and some of the Greek islands in the Aegean Sea.

I spent several hours this afternoon and early this evening dissecting, positioning & photographing the genitalia of this snail for a manuscript I am writing about it.

During mating, the snail's penis, normally kept inside its body, is everted, very much like the turning inside out of the finger of a glove. So, during a dissection, to see what the outside of a penis looks like, one needs to cut open the penis and look inside it.

On the inside of a penis that becomes the outside during mating (confusing, eh?), there is usually a projection called the verge (= penile papilla). Once the penis is everted, the verge becomes the tip of the penis and thru which the sperm is transferred.

The tip of the verge of Xerocrassa cretica is highly convoluted and deeply folded. So is the inside wall of the penis. I spent most of my time trying to capture that morphology in my photographs.

To take the photograph I used my Olympus E-500 with a Zuiko 35 mm macro lens and an EX-25 extension tube. The extension tube was necessary to obtain the proper magnification, but it left almost no room between the front of the lens and the subject for lights. I had to light from the side. That, however, wasn't possible with the aluminum dissecting dish I was using. So in the middle of all this, I had to make a new dissecting dish with glass sides. Luckily, I had a small Pyrex petri dish. I put some black wax in it, put it in the oven for about 5 minutes to melt the wax and 10 minutes later, the new dissecting dish was ready.

Later, while examining the picture on the computer screen, I noticed that the pin on the right had cast a long shadow across the wall of the penis and along the edge of the verge. Now, I am wondering if I should re-photograph it.

20 November 2006

A shell of a different kind

Empty shells of land snails usually accumulate soil and all sorts of debris in them, especially if they have wide apertures. One can dislodge most of what is inside the bodywhorl of a shell by squirting water inside, by gently tapping on the shell or by inserting something long and curved with a blunt tip deep into the shell. Often, the soil that comes out of a large shell will have tiny snail shells in it. Therefore, it is a good idea to sort thru that soil before discarding it away.

Yesterday afternoon I examined some land snail shells (in the family Hygromiidae, to be specific) that had been collected near a beach. A small amount of beach sand came out of the shells, which I collected in a small dish. And before tossing it away, I scanned it under the stereomicroscope. Among the tiny sand grains was this tiny foraminiferan shell almost exactly a millimeter wide.


Foraminifera, called forams by those who study them, are mostly microscopic and exclusively marine organisms in the kingdom Protista.

In the 1950s, the Foraminifera, along with other microscopic organisms ("protozoa"), were considered to be animals. For that reason, there is a chapter about them in Invertebrate Fossils by Moore et al1. Many foraminiferan shells (tests) look quite like snail shells. And like snail shells, most foraminiferan shells are also made of CaCO3.

Some forams with snail-like shells. Drawings from Moore et al1.

1. Moore, Lalicker & Fischer. 1952. Invertebrate Fossils. McGraw Hill.

18 November 2006

My new bright toy


Soon after I bought my Olympus E-500 last December, I started searching for a light set-up for close-up photography, especially for outdoor use. For a while, I experimented with various combinations of LED lights attached on flexible arms to the camera body. But, they were either not bright enough or difficult to position properly. The built-in flash of the camera works fine up to a certain magnification after which the shadow of the lens is cast upon the subject. Also, flash light frequently creates harsh shadows.

Mini L Ring fits into the palm of your hand.

So when I saw this device in B&H Photo-Video's catalog about a week ago, I realized it was just what I had in mind. It arrived in yesterday's mail and I have been testing it since then.

Digi-Slave Mini L Ring Ultra contains 24 bright LED lights. It screws into the front of the lens. This model is for lenses with 52 mm threads. (There is another and more expensive model for cameras with larger threads.) A small dial is used to adjust the light intensity, although for most applications when the camera is hand-held, the highest intensity seems to be necessary to avoid using too slow a shutter speed.

Mini L Ring runs on either a 9V battery or a 9V DC wall transformer. The interesting thing was that the B&H catalog gave me the impression that a wall transformer was not supplied with this model and the instructions that came with the unit stated that a wall transformer was available for purchase from the company. Yet, there was one inside the box. The transformer is very useful if you, like me, do a lot of indoor macrophotography of specimens.

The light intensity of Mini L Ring is bright enough to be used as the sole light source in the absence of other lights. I especially tested for that, because I frequently go out at nite to photographs snails and slugs. The picture of the Anguispira fergusoni shell (diameter: 8.5 mm) below was taken with Mini L Ring in an otherwise dark room with a shutter speed of 1/80 s at f8 and at an ISO of 320. You will notice that there is an overexposed ring surrounding the shell in the middle. This is probably an unavoidable result of using a ring light relatively close to the subject. Once the picture is cropped, sharpened and its contrast increased slightly, however, it looks fine and evenly illuminated (second picture).



The biggest problem in using LED lights for photography is that they tend to cast a bluish hue. My camera's auto white balance setting cannot correct for that. I did a series of test shots while manually changing the color temperature setting of my E-500. I determined that the most correct color hues are obtained when the color temperature is set at about 9000 K. That was the color temperature setting I used for the shot of Anguispira fergusoni and made no subsequent color corrections. Outdoors, however, depending on the intensity of sunlight, a lower color temperature setting may be necessary (see the pictures below).

The part of the unit that sticks out in front of the lens is 27.8 mm thick, but it still leaves room to approach the subject close enough to establish focus at the highest (1:1) magnification of my Zuiko Digital 35 mm macro lens. I photographed the lens cap at 1:1 magnification (camera was handheld at 1/60 s, f6.3, ISO 400). The uneveness of the light intensity is more obvious (it gets brighter towards the edges), but I think the result would be acceptable for most purposes.


There are a few other drawbacks of Mini L Ring. At low magnifications the unit may slightly vignette the edges of the frame. And in certain configurations, especially outdoors, the battery compartment may get in the way and prevent one from bringing the lens close enough to the subject.

Those are, however, insignificant concerns. Once you figure out the correct white balance setting, this is a very useful light source for macrophotography.

Digi-Slave Mini L Ring Ultra is manufactured by the SR Inc.

I photographed the tiny Vertigo pygmaea dormant on a rock and the tiny aphid on a dead milkweed seed pod in my backyard this afternoon under an overcast sky using Mini L Ring as a fill-in light source. Both subjects were slightly underexposed, but that could have been avoided. The white balance was set at 9000 K for the aphid picture and at 8200 K for the Vertigo picture. No subsequent color corrections were made.

17 November 2006

16 November 2006

Rossmässler's Iconographie


In 1835, E. A. Rossmässler, one of the best known malacologists of the 19th century, started publishing a series of volumes under the long title Iconographie der Land- und Süsswasser-Mollusken mit vorzüglicher Berücksichtigung der europäischen noch nicht abgebildeten Arten. If I am translating it correctly, the title means Iconography of land and freshwater mollusks with principal consideration of not yet pictured European species.

Around 1877, another German malacologist, W. Kobelt took over and continued the publication of the Iconographie until the early 20th century.

Because of its age, the Iconographie is not an essential book to have anymore. But, mostly because Rossmässler and Kobelt described several new species on its pages, it occasionally becomes useful (even necessary) to consult it.

Imagine my pleasant surprise, then, in the library of the Delaware Museum of Natural History last October when I discovered a complete set of the Iconographie. Photocopying or photographing every single page would have been too time consuming. Instead, I decided to photograph only the plates for land snails. Luckily, they had a nice copy stand complete with lights that made the job quite easy.

Of course, one problem with using a book as old as the Iconographie is that the names of most, if not all, species have changed so many times since the 19th century that one needs to consult synonymies to figure out for certain which species is which. Here is a detail from one of the plates showing 2 common European species. Number 322 Pupa granum is now Granopupa granum, whilst No. 327 Pupa umbilicata is Lauria cylindracea.


In October, I had time to photograph the plates in only 4 of the volumes. The next time I am at DMNH I hope to do more.

15 November 2006

Be halophilic or be square!

The halophilic (salt-loving) archaeon Haloquadratum walsbyi is, of course, both. This organism thrives in habitats where you and I and just about every other organism on earth would shrivel up into a lifeless bag of desiccated stuff.

The natural habitat of H. walsbyi is NaCl-saturated pools that also have very high MgCl2 concentrations and are subject to high solar irradiance. In such places, the low water concentration, decreased solubility of oxygen, high solar radiation and Mg2+ ions, which reduce the availability of some nutrients by forming complexes with them, turn survival into a big challenge.

A recent paper by Bolhuis et al.1 discusses the genomic characteristics of H. walsbyi and explains some of the unique adaptive traits H. walsbyi has evolved to survive in its extreme habitat.

Two of those traits attracted my attention. One is a gene that encodes a huge 9,159-amino acid long protein called halomucin. The authors note that halomucin "is similar in amino acid sequence and domain organization...to animal mucins, which play an important role in protecting various tissues against desiccation (e.g. in bronchial epithelium and eyes) or harsh chemical conditions (e.g. in epithelia along the digestive tract)... In function, mediating a specific adaptation to desiccation stress, halomucin resembles the mucous cocoon of lungfish that can escape dehydration for several years outside the water." This is either an example of convergent evolution or the genes encoding for halomucin and animal mucins are the descendants of some very old ancestral gene that encoded a similar protein.

According to the authors, the extreme flatness of H. walsbyi (0.1 - 0.5 micrometer) gives it the honor of being the microbe with the highest surface to volume ratio. Its high surface to volume ratio makes it easier for H. walsbyi to obtain enough nutrients from its environment.

The other interesting finding is that the genome of H. walsbyi encodes 2 bacteriorhodopsin proteins. These proteins help H. walsbyi turn solar energy into chemical energy: "Similar to solar panels, the ultra thin cells of H. walsbyi
collect light as alternative energy source making optimally use of both sides of the membrane."

But they still don't know how H. walsbyi maintains its square shape.

1. Henk Bolhuis, Peter Palm, Andy Wende, Michaela Falb, Markus Rampp, Francisco Rodriguez-Valera, Friedhelm Pfeiffer, Dieter Oesterhelt. The genome of the square archaeon Haloquadratum walsbyi : life at the limits of water activity. BMC Genomics 7:169 (4 July 2006). pdf

14 November 2006

A sidewalk puzzle


This is a picture of a sidewalk a few hours after a rain. It was mostly dry except for the spots covered by leaves. (The couple of leaves without wet spots under them had probably been blown on the sidewalk after it dried.)

So, here is my question: why were the wet spots under the leaves wider than the leaves themselves?

And, here is what I think is the answer: as the sidewalk was drying, the water prevented from evaporating by the leaves diffused out from under the leaves into the dry concrete creating a wet spot larger than the leaf area. The extent of the wet spot was probably determined by the amount of water that was originally under each leaf and the rate of evaporation opposed by the rate of diffusion of water.

If you can think of a better answer, please post it.

13 November 2006

Funeral march for a dead slug

The desiccated remains of slugs and earthworms are common sights on sidewalks around here on warm mornings. Those are the ones that couldn't make it back to a wet refuge after the sun rose and started heating up the concrete. I have written about one such unfortunate slug here.


During a morning walk about a month ago, I came upon this casualty (arrow in the picture) at the end of a long and twisted slime trail that was shining in the bright, warm sun. It turned out to be a Limax maximus.

What is so puzzling about this slug’s behavior during its last journey is why it didn’t enter the grassy area on the right (where the soil would have been wet and cooler) when it came so close to it so many times. Once or twice it even seems to have passed under the grass blades growing across the sidewalk.

Can they not tell that they are overheating and drying until it is too late? Or, can they not sense a wet and cool spot from a few centimeters away? Obviously, slugs did not evolve to live on wide and refugeless concrete surfaces, but I would think that air temperature and humidity would have some bearing on their direction of travel.

Maybe this one was one of the "least fit" ones that had something wrong with its senses. It is now resting in a bottle of alcohol.

11 November 2006

An old tomb of some sort


This ancient structure, surrounded by a nice little park, is located near the western end of the city of Milas (ancient Mylasa) in southwestern Turkey. I photographed it last July when I walked past it. Unfortunately, I didn’t have time to examine it more closely.

It is known by its Turkish name Gümüşkesen (ş=sh), which means "silver cutter". How it acquired that name, I have no idea.


Although apparently there isn't much known about it, it is considered a significant monument, because it is believed to have been modeled after the Mausoleum that once stood in Halicarnassus1, 2. Jeppesen2 calls it a Roman tomb and according to Akurgal1 it is probably from the 2nd century A.D. Bean3 gives some structural information and indicates that the door in the front provided access to the grave-chamber.

It is not known who was buried in it.

1. Akurgal, E. 1973. Ancient Civilizations and Ruins of Turkey.
2. Jeppesen, K. undated. The Maussolleion at Ancient Halicarnassus. [Booklet purchased at the Mausoleum in Bodrum, August 2002.]
3. Bean, G. 1971. Turkey Beyond the Maeander.

10 November 2006

Boxcar graffiti XXXIV



09 November 2006

Watch out for the wall!

A Ballade of Evolution

By Grant Allen

In the mud of the Cambrian main
Did our earliest ancestor dive:
From a shapeless albuminous grain
We mortals our being derive.
He could split himself up into five,
Or roll himself round like a ball;
For the fittest will always survive,
While the weakliest go to the wall.

As an active ascidian again
Fresh forms he began to contrive,
Till he grew to a fish with a brain
And brought forth a mammal alive.
With his rivals he next had to strive
To woo him a mate and a thrall;
So the handsomest managed to wive,
While the ugliest went to the wall.

At length as an ape he was fain
The nuts of the forest to rive;
Till he took to the low-lying plain,
And proceeded his fellow to knive.
Thus did cannibal men first arrive,
One another to swallow and maul;
And the strongest continued to thrive,
While the weakliest went to the wall.

Printed at the end of Allen's long essay The evolutionist at large published in the November 1881 issue of the Humboldt Library of Popular Science Literature.

Allen's essay is available from Google Books as part of a large (70 MB) compilation called Christian Pamphlets. The inclusion of The evolutionist at large in that compilation is odd because Allen was an agnostic who strongly believed in evolution as his essay demonstrates.

Incidentally, Allen presents in his essay a surprisingly well argued discussion of the evolution of slugs from shelled snails.

08 November 2006

Papers read this week

Steven H. Ferguson. 2004. Effects of poisoning nonindigenous slugs in a boreal forest. Can. J. For. Res. 34: 449–455. Abstract

This is a poorly designed study. The author’s purpose "was to determine the abundance changes of soil arthropod groups associated with removal of a significant invasive group from the forest habitat and to relate abundance changes to soil arthropod diversity." So far, so good. But what invasive organism did the author pick? The "exotic Deroceras leave", a species that is usually considered to be native to North America. And he gives no explanation of why he thought D. leave may have been introduced to his study site. It may very well have been an introduced species there, but how do we know that?

Next, what method of removal of the "invasive" slug did the author pick? The poison metaldehyde, tablets of which were left at study plots. And when his results showed something he was perhaps not expecting, he was left without an explanation: "significant removal of one of these invasive groups, slugs, resulted in a decline in abundance of three other arthropod groups, Collembola, mites, and nonindigenous isopods. Reasons for these changes were not obvious." But later, he adds "Without further experimentation, metal poisons may have been toxic to these invertebrates." Duh! Shouldn’t you have tested that before the study? Wouldn’t it have made more sense to hand pick and remove the slugs periodically rather than use a poison with uncertain effects on the rest of the biota?

It is hard to believe this paper got accepted for publication. And it is harder to believe I wasted my time not only reading it but also writing about it.

Mark Blaxter, Ben Elsworth, Jennifer Daub. 2004. DNA taxonomy of a neglected animal phylum: an unexpected diversity of tardigrades. Proceedings: Biological Sciences Vol. 271, Biology Letters Supplement 4, Pages: 189 – 192. Abstract

A few years ago, Finlay1 argued in Science that that "there is little support for the idea that microbial eukaryote species are geographically restricted" and, therefore, there were probably no endemic microbial species. He concluded that "free-living microbial eukaryotes, all of which have body sizes less than about 2 mm, are probably sufficiently abundant to have worldwide distribution."

The authors of this study applied a DNA barcode system to tardigrades from urban and rural sites in southern Scotland and defined molecular operational taxonomic units (MOTU). Tardigrades are microscopic, aquatic animals that live in various semi-terrestrial habitats, such as mosses and lichens (but also in the sea). Because of their small sizes (most less than 1 mm in size) and their ability to survive drying that increases their chances of transportation by winds, most species are expected, following Finlay’s reasoning, to have a global distribution.

The authors claim that they did not observe a "global" distribution pattern when they mapped their MOTU, but instead found a disjunct distribution pattern between urban and rural sites.

What is the problem with this interpretation? They are comparing apples to oranges, that's what the problem is. The distribution of a group of microbial eukaryotes within Scotland doesn’t represent a global sampling effort. If the distribution of a group of microbial eukaryotes, especially between urban and rural sites, over an area (in this case, Scotland) that is relatively small compared to the overall global land mass is disjunct, one cannot extrapolate from this to the distribution of the group over the entire earth. But that’s exactly what the authors claim: "…our data from just three closely spaced sites suggest that tardigrades do have a biogeography." I rest my case.

1. Bland J. Finlay. 2002. Global Dispersal of Free-Living Microbial Eukaryote Species. Science : 1061-1063. Abstract

07 November 2006

A lord in Europa Minor

At a time when Turkey's chances of joining the European Union seem to be rapidly diminishing, it might be pertinent to revisit this 1956 book, if anything, for its title the British author Patrick Balfour (1904-1976), who was perhaps better known as Lord Kinross, justified as follows.

It is a title incidentally which, in the political sense, might well be applied to modern Turkey as a whole. For the Turkish Republic, built by Atatürk on western foundations, is gradually developing, like Greece its neighbour, into an integral part of Europe.


Lord Kinross's book chronicles his many trips along the southern and western coasts of Turkey between 1947 and 1954. Unfortunately, he doesn't give specific dates and the chapters may not always follow a chronological order.

That was a time when paved roads, tourism (foreign and domestic) and the associated development hadn't yet entered Turkey. Travel was difficult by today's standards, World War II restrictions preventing foreigners from entering certain towns without permits (for example, Çanakkale at the mouth of the Dardanelles) were still enforced and trips to archaeological ruins were unheard of and looked upon with suspicion.

One of the highlights of the book is a long yacht trip Lord Kinross took from Antalya on the south coast to the southwest of Izmir on the west coast. This was decades before such yacht trips along the now heavily polluted coasts, nevertheless romanticized as "blue voyages", became fashionable (I have done 2 of them).

During his travels, Lord Kinross met many interesting characters. In Ermenek, a southern town, a World War I veteran who had learned English from the British after he had been taken prisoner by them (but who hadn't seen an Englishman for 28 years) befriended him, however briefly. In Bodrum, a drunk sponge fisherman told him about the wreckages of the British aircraft shot down during World War II that he had discovered during his dives. On the yacht, he listened to the stories of Mehmet the cook, another World War I veteran. He was a kurd who had fought on the Russian front: "Armenians kill plenty Kurds...But afterwards Kurds kill plenty Armenians."

Travel diaries by Turkish authors from the 19th and the early to mid 20th centuries are almost nonexistent. The books by foreign travellers are, therefore, priceless not only in their accounts of the country side, people, customs and culture, but also in revealing how their authors evaluated and almost always related to the Turks. Europa Minor is one of the better examples of that genre.

06 November 2006

A skeleton from the family closet


This is a picture of my father (the one with the hat) taken in the summer of 1940 in the town of Boyabat in northern Turkey. If I am remembering it correctly, he was the hükümet doktoru (government doctor) of the town with duties including those of a coroner. Based on what little visible of the surroundings and the condition of the corpse, I guess the picture was taken outside of the town.

As for additional details of the case, I have none.

04 November 2006

Train station casualty


I found this common buckeye (Junonia coenia) on a step of an enclosed stairwell at Silver Spring train station the other day. It was a few meters away from the doorless entrance. Could it have been struck by a train and blown in by the wind?

Ironically, this is the first common buckeye I have ever photographed.

03 November 2006

Today's find at the used bookstore

This is the 1971 revised edition of Jacobson & Emerson's Shells from Cape Cod to Cape May originally published in 1961. First I thought it was solely about seashells, so I was putting it back on the shelf when I noticed that it also had a section on land snails (in addition to marine and freshwater mollusks). The descriptions and figures were pretty good and there was quite a bit of useful historical information such as this.

In 1891, a colony of this snail [Stenotrema hirsutum] was recorded "in a small patch of woods" at what is now 13th Avenue and 74th Street, Bay Ridge, Brooklyn. When we visited this spot recently, we found only concrete, bricks and steel occupying the location.

So I decided the price tag of $2.00 was worth the book.

The foreword, written by R. Tucker Abbott, starts as follows.

New Yorkers have an undeserved reputation of being subway moles living in a greenless world of night lights and smog. This idea is preposterous for two obvious reasons. Firstly, there is as much natural history to be observed in the parks, backyards and nearby beaches of New York City as there is in almost any other part of our country.

02 November 2006

Spiderman accepts Islam, kneels down for prayer

Namaz is the name given to each of the 5 prayer sessions a Moslem is required to perform daily. The title of this "book" is "I am learning how to perform namaz".

A joke started by the Turkish parody site Haybe Dergi (Haybe Magazine) claiming that the Turkish government's Religious Affairs Office had published a children's book featuring the Spiderman as a Moslem appears to have created quite a furor.

The original "news" item appeared here featuring excerpts from the interviews with the head of the Religious Affairs Office explaining why they had picked the Spiderman for a book aimed at teaching children how to carry out the daily prayer sessions. Furthermore, it was claimed that the book had been met with disapproval: in New York Spiderman fans had protested the Marvel Comics' apparent endorsement of the book, while in Turkey a religious group had pointed out that because the Spiderman's costume would prevent his forehead from touching the ground, his prayers would not be acceptable.

According to this real news article from 20 October 2006, after one of the regular writers of the daily newspaper Hürriyet mentioned the book, apparently without realizing its true nature, the Religious Affairs Office started receiving so many inquiries about it that they had to issue a statement explaining that there was no such book.

It looks like Spidey won't be fighting the infidel this year.

Note added 23 April 2008: I have just learned that Haybe Dergi ceased publication after the 1st issue (apparently for financial reasons) and closed down its Internet site. The link to the Hürriyet news article is still operational though.

W's parrot

Laura Bush bought George a parrot for his birthday.

She told Dick Cheney, "The bird is so smart! George has already taught him to mispronounce over 200 words!"

"Wow, that's pretty impressive," Cheney said. "But you realize that he just says the words. He doesn't understand what they mean."

"That's okay," Laura replied. "Neither does the parrot."

01 November 2006

A mushroom eater

When Rafinesque erected the slug genus Philomycus, he explained that their name meant "friend of fungi". He had picked that name for them, because, Rafinesque wrote, they feed on fungi. (A reproduction Rafinesque's description is in this old post.)


The slug in this picture is Philomycus carolinianus, a native of eastern U.S. forests. This particular individual is living in a plastic box in my basement at the moment. It indeed likes to eat the mushrooms from my backyard as it was doing when I took its picture.

The smaller slug below it is an Arion intermedius, an introduced species from Europe.