25 June 2005

Blog break until July 1st

Tomorrow morning at 7:00 I will leave from the Dulles Airport for Monterey, CA. I live about 45 min away from Dulles. You can imagine what time I'll be getting up. Monday thru Wednesday, I will be at the annual meeting of the American Malacological Society and be back home sometime after midnight Friday morning. You can imagine what time I'll be going to bed.

My presentation, entitled The diversification of the family Enidae in Turkey: an evolutionary perspective, is scheduled for 11:10 on Monday morning.

Abstracts of the meeting are here.

While I am gone don't forget to feed the plants and water the cats.

July 1st: a day to celebrate evolution

On 1 July 1858, Charles Darwin’s and Alfred Russel Wallace’s ideas on evolution by natural selection were made public for the first time before the Linnean Society in London.

Darwin had been developing his ideas for 20 years, but before that day he had revealed them only to a few close friends and correspondents, including the American botanist Asa Gray. Wallace, on the other hand, had come up with his version of natural selection, very much similar to that of Darwin's, a few months earlier while doing fieldwork in the Malay Archipelago and communicated it to Darwin in a letter.

The presentation at the Linnean Society was initiated with a letter of introduction by Darwin’s close friends Charles Lyell and Joseph D. Hooker, opening with the words:

My Dear Sir, -- The accompanying papers, which we have the honour of communicating to the Linnean Society, and which all relate to the same subject, viz. the Laws which affect the Production of Varieties, Races, and Species, contain the results of the investigations of two indefatigable naturalists, Mr. Charles Darwin and Mr. Alfred Wallace.

This was followed by the reading of extracts from an unpublished essay Darwin had written in 1844, part of his 1857 letter explaining his ideas to Gray and the manuscript Wallace had sent to Darwin.

What better thing is there to do on July 1st than learning about evolution? Read a book on evolution, teach someone about evolution, visit a natural history museum or take a hike in the woods. And don’t forget to remember Darwin and Wallace, for, after all these years, their idea remains indefatigable.


24 June 2005

Thank cats it's Friday

I am the Cat who walks by herself, and all places are alike to me.

23 June 2005

A fiery predator of snails


I found this firefly larva 2 years ago at the University of Michigan's Biological Station in Michigan's Upper Peninsula. When I first saw it in the woods, it was eating a snail. Even after I picked it up and carried it to my cabin in a vial, it kept on eating the snail. Subsequently, I brought it to Maryland, where it survived in my lab for several months feeding on snails and slugs. It went through one instar stage and I was hoping that it would eventually turn into an adult, but it died before becoming one.

The species of snails it ate in the lab were Cochlicopa sp., Oxyloma retusa (pictures above), Ventridens ligera and a juvenile specimen of the slug Deroceras reticulatum. It never seemed to have any difficulty overcoming the snails; it would simply force its way into the snail's aperture and attack it right away. Deroceras reticulatum, on the other hand, gave it a hard time. The first time it attacked the slug, the latter secreted such a large amount of slime that the larva got immobilized for more than 10 minutes before it could eat its way out of the slime. In the meantime, the slug crawled away. Under natural conditions that would have been the end of it. But they were in a small container and I was anxious to see if the larva would succeed. So, I kept bringing them together. Eventually, after several more attacks, the larva managed to overcome the slug.

LaBella & Lloyd1 cited some old references that claimed that the firefly larvae inject into their prey a poison to stun it. Symondson2, on the other hand, stated that the snail-eating larvae of several species of fireflies were not believed to inject poisonous substances into their prey. My observations of the slug mentioned above support the latter position, for the slug kept on moving and struggling even after the larva had bitten it.

The larvae of all fireflies (Lampyridae) are predaceous. This time of year I always get fireflies in my backyard. I don't know what their larvae eat though. I don't have any large snails, but there are lots of slugs. Some species are also known to eat earthworms and the larvae of other insects.

1. LaBella, D.M. & Lloyd, J.E. 1991. Lampyridae. In Immature Insects (Stehr, F.W., ed.), II:427.
2. Symondson , W.O.C. 2004. Coleoptera as predators of terrestrial gastropods. In Natural Enemies of Terrestrial Molluscs (Barker, G., ed.).

How does macroclimate influence land snail distribution patterns?

In my previous posts on the land snails of the family Enidae in Turkey (here and here), I concluded that macroclimate doesn’t seem to have had a major influence on the ranges of these snails.

My obvious (at least, to me) conclusion was based on the simple observation that the ranges of several species and genera extend over more than one climate zone. Lest I am accused of jumping into this conclusion without the benefit of a sophisticated analysis, I will now point out that 2 recent studies using more sophisticated methods made more or less similar determinations for the land snail faunas of nearby regions.

Kadmon, R. & Heller, J. 1998. Modelling faunal responses to climatic gradients with GIS: land snails as a case study. Journal of Biogeography, 25:527-539.
Kadmon & Heller analyzed the distribution patterns of land snails in Israel using GIS tools and determined that “Above 450 mm [mean annual rainfall], no relationship could be detected between the observed patterns of faunal variation and rainfall”. And they concluded that the “effect of rainfall on land snail distribution diminishes from the relatively arid parts of Israel towards its more rainy parts, and that factors other than rainfall are important in determining the distribution of land snails in the Mediterranean region”.

Their result makes sense to me, because I suspect that animals that normally live in arid regions require special adaptations to survive the scarcity of water that the animals living in areas that receive more precipitation don’t necessarily need. In other words, once the mean annual precipitation level is above a certain threshold (400?-450? mm), I suspect that any or most snails may survive indefinitely provided that their other ecological requirements are also satisfied.

Hausdorf, B. & Hennig, C. 2005. The influence of recent geography, palaeogeography and climate on the composition of the fauna of the central Aegean Islands. Biological Journal of the Linnean Society Volume 84:785-795.
Hausdorf & Hennig used partial Mantel tests and structural equation models to investigate the influence of recent geography, palaeogeography and climate on the composition of the fauna (land snails, land isopods, tenebrionid beetles, butterflies and reptiles) of the central Aegean Islands. They determined that “There was no significant influence of recent climatic parameters, mean annual temperatures and annual precipitation on the composition of the land snail, land isopod, tenebrionid beetle and butterfly faunas of the central Aegean Islands, if recent distances between the islands were controlled for”. According to their results “the composition of land snail island faunas has been influenced by recent and by Pliocene distances [between the islands]”.

My tentative conclusion in an earlier post regarding the Turkish Enidae was that their present day distributions had resulted mostly from Miocene and older geography.

22 June 2005

Sleeping the summer away

Land snails are well known for their abilities to survive adverse environmental conditions, especially the lack of water and food. In one oft cited case, first reported in the 19th century1, one specimen of the Middle Eastern species Eremina desertorum survived almost 4 years attached to a display case in the British Museum. Sphincterochila boissieri, another tough species, lives in the Negev Desert in Israel. The body temperature of one snail aestivating in the sun was recorded at 50.3 °C, about 5 °C below lethal temperature2.

The Mediterranean summers are notoriously hot and dry. Rains usually end in May and don't start again until October. For example, along western and southern coastal areas of Turkey the average monthly total rain is barely 1 mm in each of the months July and August.

The land snails that inhabit such places spend about five months of the year in aestivation. Many species aestivate under the rocks or buried in soil, where they obtain protection from the direct heat of the sun. But, some species aestivate on exposed surfaces of rocks, sometimes fully in the blazing sun, and survive.

Recently, I reported the survival of some specimens of the clausiliid land snail Albinaria without getting liquid water from the outside for up to about 13 months3. This is possible apparently because the aestivating snails metabolize at a very low rate2, and consequently, their metabolic reserves can last a long time. In the long run, this over-adaptation must be an indispensable safety mechanism, because, without it, one unusually long dry period lasting, for example, 7 months rather than the ususal 5, would kill all the snails.

Albinaria caerulea aestivating attached to limestone rocks near Istanbul, Turkey (June 2004).

1. Stearns, R.E.C. 1877. On the vitality of certain land mollusks. American Naturalist, 11:100-102.
2. Schmidt-Nielsen, K., C.R. Taylor & A. Shkolnik, 1971. Desert snails: problems of heat, water and food. Journal of Experimental Biology, 55:385-398.
3. Örstan, A. 2005. Aestivation survival in some Turkish Albinaria species. Spirula, No. 342, pp. 3-4.

20 June 2005

The Cardinals at the limit of my hearing

I was 23 or 24 when I first realized that my right ear didn't hear as well as my left one. One afternoon, I was sitting a few meters from an open window studying for an upcoming exam. I noticed that I could hear the sounds coming from the outside better when my left ear was facing the window than otherwise. I figured as long as I intended to keep studying, it was best to have my right ear turned to the window.

It's been more than 20 years since, and fortunately, my hearing hasn't deteriorated as far as I can tell. I suspect it is a genetic condition, for not only was my father somewhat hard of hearing too, but his sister was half-deaf; when we spoke to her we would be practically yelling and even then she could not understand many words.

Late yesterday afternoon I was out on my deck enjoying my solitude with a glass of beer and some reading material when these male and female Northern Cardinals (Cardinalis cardinalis) showed up. I rushed inside to get my camera and luckily, they stayed.

I could barely hear their high pitched (to me, at least) chirps that one bird book calls a "sharp chink". So, on a scale from a pin hitting the floor to the thunder of a lightning hitting my roof, the limit of my hearing is at the Cardinal's chink level.

19 June 2005

They've seen the light! Hallelujah!

After I saw one of these at jimmy the magnet, I just had to make my own here.

The land snail family Enidae in Anatolia 6: if shells don't tell, look inside

The family Enidae is characterized by mostly tall shells with or without apertural teeth. Among the Turkish enids there are some genera with superficially similar shells.

For example, the shell of Borlumastus yildirimi, below (left),


looks quite like that of Imparietula leucodon, below (left).


Although I. leucodon tends to be slightly larger, the resemblance is striking.

However, their genitalia tell a different story. Imparietula leucodon has an appendix (a), which B. yildirimi lacks. Furthermore, in B. yildirimi bursa copulatrix (bc) has a diverticulum (d) and the epiphallus (e) has a flagellum (f), while both of which are absent in I. leucodon.

It appears that although the genitalia diverged during evolution, the overall shell morphology was maintained. Either that or the shell morphologies were initially different, but subsequently converged to similar morphologies.

1. The shell and genitalia pictures of B. yildirimi are from: Örstan, A. & Yıldırım, M.Z. 2004. Borlumastus, a new land snail genus from Turkey (Gastropoda: Pulmonata: Enidae). Basteria, 68:125-129. pdf
2. The shell picture of I. leucodon is from: Bank, R.A. & Neubert, E. 1998.
Notes on Buliminidae, 5. Systematic position of Arabian Buliminidae (Gastropoda Pulmonata) with the description of a new genus. Basteria 61:73-84;
the genitalia picture is from: Hesse, P. 1933. Zur Anatomie und Systematik der Familie Enidae. Archiv für Naturgeschichte NF 2:145-224.
3. Other abbreviations: p, penis; v, vagina; c, caecum; vd, vas deferans; go, genital opening; rp, retractor of penis; fo, free oviduct.

17 June 2005

Friday nite's beer review: Black Chocolate Stout from New York

Mmmm...chocolate. This beer, from the Brooklyn Brewery in Utica, NY, indeed has a nice chocolaty aroma. It is also very dark and slightly bitter. Overall, it has a unique, strong flavor.

Even though there is no Internet address on the label, the Brooklyn Brewery does have a Web site (who doesn't?). It's silly but you have to enter your birth date to go beyond the first page. I entered 1900 as my birth year and was granted admission. I guess they don't mind really old folks drinking beer.

According to the Web page, the chocolate flavor is obtained "through a blend of specially roasted malts". Apparently, it is brewed once a year for winter. But the page claims that it ages "very nicely for years, becoming even more complex in flavor". Maybe I will set a bottle aside.


Previous beer reviews:
Coopers Extra Stout from down under
Efes from Turkey

Natural selection at work: wild dogs hunting impala

... if variations useful to any organic being do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterised. This principle of preservation, I have called, for the sake of brevity, Natural Selection.
Charles Darwin, On the origin of Species, 18591

Another way to express what Darwin meant is that individuals with characteristics that are useful to them in their struggle to survive are more likely to produce offspring with the same characteristics. One straightforward consequence of Darwin's idea is that animals that are sick or injured will be less successful to defend themselves against predators or to escape from them. Therefore, such individuals are more likely to be killed by predators before they have a chance to reproduce. This is so obvious that it should hardly need to be proven. Nevertheless, it has been demonstrated to take place in the wild many times. One example involving African wild dogs (Lycaon pictus) and their prey impala (Aepycerus melampus) in Zimbabwe was published recently2.

African wild dogs

African wild dogs (also called African hunting dogs) hunt in packs and share their kill. One large animal that wild dogs prefer to hunt is impala. Once a pack finds an impala, or any other prey, they begin to chase it until the prey gets tired and they catch up with it. Such chases can apparently last for several kilometers at high speeds. Obviously, this hunting method is energetically very costly. Imagine yourself having to run, say, 2 kilometers (about 1.3 miles) as fast as you can before your every meal. Just to obtain enough energy to be able to run 3x2 fast kilometers a day, you would probably have to eat an extra meal every day, but that would make it necessary to run 2 additional kilometers!

This being the case, which impalas would a pack of wild dogs rather go after to minimize their energy expenditure during a hunt? Undoubtedly, the weak and the sick ones, because they will be slower than the healthier animals, and by chasing the slower impalas the wild dogs will spend less energy.

Impalas in Africa

To determine if this was indeed what was happening in the wild, British scientists2 collected bone marrow from one group of impalas that had been killed by wild dogs and another group that had been killed non-selectively by humans. They knew from previous studies that impalas in poor condition had very little fat in their bone marrows. Therefore, as a measure of the physical condition of each impala they calculated the amount of fat it had in its bone marrow at the time of its death. The graph below shows their results.

The impalas that had been killed by wild dogs (bottom curve) had significantly less marrow fat than the impalas that had been killed by humans (top curve). Therefore, the authors of the study concluded that wild dogs selectively prey on impalas that are in poorer condition.

A more general result that we can derive is that the weaker impalas are less likely to live long enough to reproduce, while the stronger ones are more likely to escape from wild dogs (and other predators) and live long enough to reproduce. What does this mean in terms of evolution? It means that the healthier and stronger impalas are more likely to pass the genes that contribute to their good health and physical strength onto their offspring. In turn, their offspring will be more likely to be healthy and so on. This is basically how natural selection works.

Dinner is being served

For more information follow these links.

Natural selection 1
Natural selection 2
African wild dog 1
African wild dog 2
Impala 1
Impala 2

1. Charles Darwin, On the Origin of Species, 1859. full text
2. Alistair Pole, Iain J. Gordon and Martyn L. Gorman. African wild dogs test the 'survival of the fittest' paradigm. Proc. R. Soc. Lond. B (Suppl.) Biology Letters 270, S57 (2003).

Wild dog and impala pictures were downloaded from the University of Michigan Museum of Zoology Animal Diversity Web

Cross-posted at Transitions

15 June 2005

The land snail family Enidae in Anatolia 5: seeking answers from paleogeography

The conclusion from the previous post is that there are 3 elements in the Anatolian biogeography of the Enidae: north-northwestern, east-northeastern and southern. Assuming that the present day distributions more or less reflect past ranges (see the cautionary note at the end of last post), I will now turn to paleogeography of Anatolia to try to understand these distributions.

The first map shows what Europe, northern Africa and the Middle East may have looked like about 15 million years ago1. Turkey and the Black Sea north of it are more or less recognizable, except that the Aegean Sea hasn’t opened yet.

Now, let’s go 50 million years further back.

Back then, there wasn’t an area recognizable as “Turkey”. However, we do see several land masses where Turkey will eventually be. There is a southern land and a group of northern lands. These all get together during the following 30 millions years to form the present day Turkey.

Therefore, it seems that the roughly northern and southern groupings of the present day Turkish Enidae have their origins in the distributions of land masses 65 million years ago. Of course, the ancestors of the present day enids could be much older than that.

1. Maps were created using the ODSN Plate Tectonic Reconstruction Service.

14 June 2005

Escher’s sinistral snail

The Dutch artist M. C. Escher (1898-1972) frequently incorporated birds, fishes and insects into his works. In addition, marine mollusks were the sole subjects of two of his drawings (Sea-shell, 1919/1920 and Sea-shells, 1949) and a marine gastropod was depicted on the bottom of the sea in The Fifth Day of the Creation, 19261.

A closer scrutiny of his works revealed three appearances of land snails. The first example, a detail from Castrovalva, 1930, shows a snail shell, perhaps an empty one, on an Italian hillside.

The second example is from Verbum, 1942, where a land snail is crawling in the company of other creatures.

The vast majority of snail shells are dextral (the coiling of the shell is right-handed). This means that when the shell is held with its aperture facing the observer and its apex pointing up, the aperture will be on the right. Nevertheless, there are some genera or even families (for example, the well-known land snail family Clausiliidae) in which the normal shell coiling is left-handed or sinistral.

The two examples above both depict dextral shells. But, Escher’s third land snail, in the lower lefthand corner of Plane Filling II, 1957, is sinistral.

Escher, who was very much into symmetry, was probably keenly aware of the fact that shells can be dextral or sinistral. Note that in Escher's print the sinistral snail's shell fits into the curvature of the fish's tail, while its tentacles fit into the spaces between the turtle's feet. The placement of a dextral snail into the same position, however, would have required the rearrangements of most, if not all, of the other creatures (and the guitar) in the picture. Escher’s sinistral snail was tailored to fit into a “niche” that was created for it in a special universe.

Occasionally, one may chance upon a freak snail specimen in the wild whose shell is coiled in a direction opposite to that of its conspecifics. Such shells are unique finds that offer us clues towards understanding the intricacies of evolution2. Can such individuals fit into the niche of their otherwise oppositely coiled conspecifics and get along just as fine? Or, unlike Escher’s snail, are they misfits in an opposite universe who are doomed to fail in the struggle for life?

1. Locher, J.L. (Ed.). 1971. The World of M. C. Escher. Harry N. Abrams, New York.
2. Örstan, A. & Welter-Schultes, F. 2002. A dextral specimen of Albinaria cretensis (Pulmonata: Clausiliidae). Triton, No. 5, pp. 25-28.

All M.C. Escher works © 2005 The M.C. Escher Company - the Netherlands. All rights reserved. Used by permission. www.mcescher.com

Text Copyright © Aydin Örstan 2005

13 June 2005

The land snail family Enidae in Anatolia 4

The first map shows the approximate distribution range of Chondrus tournefortianus. And the second map gives the approximate ranges of the genera Ljudmilena and Buliminus.

The Ljudmilena picture is from here.

Taken together with the ranges of the genus Mastus and Multidentula ovularis presented in earlier posts, I will conclude that there are 3 elements in the Anatolian biogeography of the Enidae: north-northwestern, east-northeastern and southern.

Before proceeding further, however, a word of caution is in order here. Because of geographical range extensions or contractions that may have taken place, as has been pointed out by Losos & Glor1, we cannot assume, without additional evidence, that the ranges of these taxa at the time they originated were identical to their present day ranges.

1. Losos, J.B. & Glor, R.E. 2003. Phylogenetic comparative methods and the geography of speciation. Trends in Ecology & Evolution,18:220-227.

The land snail family Enidae in Anatolia 1 - revised

During the next 3 2 weeks you have to bear with me as I post a series of pieces on the land snails of Turkey in preparation for the talk I will be presenting at the American Malacological Society’s annual meeting in Monterey, CA., at the end of this month.

My talk is specifically about the snails in the family Enidae in Turkey. Hopefully, these posts will help me organize my thoughts and prepare my slides. So, here we go.

For starters, here’s Turkey’s climate in a nut, or perhaps more appropriately, a snail shell.

There are 3 major macroclimate zones in Turkey with several transition zones in between. Northern Turkey bordering the Black Sea is characterized by what is called the Black Sea climate: rainy throughout the year with winters colder than along the southern coasts. The southern and western coasts are under the influence of the typical Mediterranean climate: hot and dry summers; rainy and mild winters. The central region is under the influence of a type of continental climate: long cold winters; short, but hot summers.

One question that is in my mind is if and how these macroclimate patterns influence land snail distributions. And today’s example is the range of Multidentula ovularis, one of the smaller (5-6 mm long), if not the smallest, enid land snail in Turkey.

The map above shows the approximate distribution range of this species; the northwest, eastern and southern boundaries of its range being approximate. Besides Turkey, the species has also been recorded from Bulgaria1.

Considering that the species ranges across 3 macroclimate zones in Turkey (Mediterranean, Black Sea and continental) and then extends further north into Bulgaria, I can conclude that Multidentula ovularis tolerates different types of macroclimate and that the extent of its range has not been influenced strongly by climate. Moreover, the range of the genus Multidentula extends south to Israel.

Note: This is the revised version of this piece that I first posted here on 6 June 2005. In the original version the range of M. ovularis included Israel, because the species is listed in Heller's book on the land snails of Israel2. However, last Friday Ümit Kebapçi in Turkey and Henk Mienis in Israel informed me that M. ovularis doesn't actually live in Israel.

It is not known at this point how far south the range of M. ovularis extends.

1. Fauna Europaea.
2. Heller, J. 1993. Land snails of the land of Israel [in Hebrew]. Ministry of Defense, Tel Aviv.

12 June 2005

Garbage can zoo: Virginia opossum

We found this opossum (Didelphis virginiana) sleeping in our garbage can one day last March. Even after I tipped the can over it stayed in it until after it got dark.

The Virginia opossum is the only marsupial mammal in North America. The female opossum has a pouch like that of a kangaroo. After the baby opossums are born, they climb into their mother's pouch and spend about two months feeding on her milk. Then they move out of the pouch to their mother's back where they spend four to six weeks.

In contrast to North America's only one marsupial, Australia has more than 200 marsupial species. Among these are the kangaroo, koala, Tasmanian devil and the wombat. Marsupials also live in South America and in New Guinea, north of Australia.

Map was from here.

Despite the fact that Australia today has more marsupial species than any other continent, the oldest marsupial fossils have been found in North America and China. This suggests that marsupials first originated on a northern continent and then spread to the southern continents.

Until about 120 million years ago there were two supercontinents. The one in the north, called Laurasia, consisted of what are now North America, Greenland, Europe, and Asia. The one in the south, called Gondwana, consisted of what are now South America, Africa, Australia, India, and Antarctica. The first marsupials must have evolved on Laurasia and spread south to Gondwana as the two supercontinets were separating from each other and breaking apart into smaller continents. This theory predicts that marsupials once lived on Antarctica when that continent wasn't covered with ice as it is now and when South America, Antarctica and Australia were directly connected to each other. Marsupial fossils have indeed been found in Antarctica.

Interestingly, all the original marsupials in North America became extinct about 40 million years ago. The Virginia opossum migrated to North America from South America about 4 million years ago.

Follow these links for more information on opossums and other marsupials:
Virginia opossum
Virginia opossum
marsupial evolution and continental drift
marsupial evolution and continental drift

Cross-posted at Transitions: The Evolution of Life

10 June 2005

Friday nite's beer review: Coopers Extra Stout from down under

G'day mates,
Australia is a place that I sure hope to visit one day. In the meantime, I will satisfy myself with this beer from Coopers Brewery in South Australia (no Internet address on the label).

This is one dark brew; light doesn't go thru it, literally. And what I liked most about it was its nice strong aroma. My wife could smell it from a chair away. The back label "warns" of a sediment, a result of the brewing process, to be expected on the bottom of the bottle. After I vigorously shook the bottle and poured some into my glass, I could indeed see particulate matter floating around. It only makes the beer more unique.


Previous beer reviews:
Kalinkin from Russia
Efes from Turkey

Don't forget to visit Henry's Webiocosm tomorrow or Sunday for another Weekend Beer Review.

09 June 2005

Book meme

This was passed on to me by Henry at Webiocosm on Tuesday, but I didn’t read it until this morning.

Number of books I own:
Gee, I don’t know. Do I have to count? I would guess about 400. I don’t have more, because I tend to get rid of the ones I don’t like.

Last book I bought:
I think it was The Seashell on the Mountaintop by Alan Cutler. It’s a pretty good book (I decided to keep it) about the life and times of Nicholas Steno who laid the principles of geology.

Last book I read for the first time:
Charles Darwin’s The Formation of Vegetable Mould Through the Action of Worms with Observation on their Habits. It’s an electronic copy I downloaded from Gutenberg. In fact, I am still reading it. It’s an amusing account of Darwin’s almost playful experiments with earthworms ("They exhibited the same indifference to my breath whilst I chewed some tobacco, and while a pellet of cotton-wool with a few drops of millefleurs perfume or of acetic acid was kept in my mouth."

I am changing the last question to:
Five Four books that have influenced me a lot:
The Theory of Evolution by John Maynard Smith - the first book on evolution that I read
Seeds of Discovery by W. I. B. Beveridge - it’s all about the scientific method
Creation Revisited by Peter Atkins - who needs a creator?
The Invisible Man by H. G. Wells - good ol’ 19th century science fiction
There’s probably more, but I can’t think of them now.

Five Four bloggers to inflict this onto:
Bootstrap analysis
Culture of Chemistry
Urban Dragon Hunters

08 June 2005

The land snail family Enidae in Anatolia 3

This map compares the numbers of known enid species in Europe, the former Soviet Union and Turkey. The species number for Europe is from Fauna Europaea, but excludes the species that are endemic to the Azores, Canary Islands and Cyprus. The species number for the former Soviet Union is from Suvorov1. And the species number for Turkey is from Schütt2 with revisions based on recent papers. All numbers are estimates. The total for Europe is probably inflated, because it contains numerous subspecies, while the Turkish total excludes them. I don’t know how the total for the former Soviet Union was calculated. Also, there are undoubtedly more species to be discovered in Turkey and in the countries of the former Soviet Union. In contrast, most, if not all, European enids are probably already described.

The bottom line is that Turkey has disproportionately more species than either Europe or the former Soviet Union. What does that tell us?

1. Suvorov, A.N. 1998. Snails of one sixth of the world’s dry land (the former
USSR).Tentacle, #8, p.6.
2. Schütt, H., 2001. Die türkischen Landschnecken. Acta Biologica Benrodis, Supplementband 4, 1–549.

07 June 2005

Mastus of the Universe

This is the second post in the series “The land snail family Enidae in Anatolia”.

There are 3 species of Mastus in Turkey: M. carneolus, M. rossmaessleri and M. etuberculatus (above). The overall range of the genus (below) extends along the Mediterranean all the way to Spain, although it is peculiar that it is not known from France along the way. However, this map is somewhat misleading, for it colors an entire country green even if there is a single record from that country, say, from one corner. Furthermore, all the records from the western Mediterranean are for one species, M. pupa. Nevertheless, the map shows that Mastus represents a north-northwestern element in the fauna of Turkey.

This distribution map was generated by Fauna Europaea with the approximate range in Turkey added by me.

Going back to the topic of yesterday’s post, the distribution of the genus Mastus, not just in areas under the influence of the Mediterranean climate, but also further up north in areas with a continental climate, demonstrates that macroclimate does not influence the range of this genus.

04 June 2005

Say’s snails: Helicodiscus parallelus


This is a land snail that Thomas Say described twice, first in 1817, and then in 1821. In his first description1, Say named it Helix lineata.


Only four years later, he described it again2, but this time placing it in the freshwater snail genus Planorbis. Say had found it in a dry pond bed and, therefore, but as his remark indicates, reluctantly, considered it an aquatic species.


It is odd that Say didn’t recognize his second specimen as being the same as his earlier Helix lineata. Or, did he? His descriptions for the two species are almost the same and their dimensions are identical. In both cases he even picked specific names, lineata and parallelus that presumably refer to the characteristic spiral lines clearly visible on the shell. I suspect that Say was aware that the two species were similar, if not identical, but the location where he had found the species the second time, “a dried up pond”, confused him. Perhaps, he thought that he was dealing with two similar looking species, one terrestrial and the other aquatic.

The shape of the shell of this snail, now called Helicodiscus parallelus, is unique among North American land snails3. It comes very close to being planispiral, meaning a shell coiled in a plane and lacking the elevated spire that we familiarly associate with snails shells.

The shells of the freshwater snail family Planorbidae are also planispiral. That is why Say picked the planorbid genus Planorbis in his second description. According to Raup & Stanley4, gastropods with planispiral shells were common in the Paleozoic. But, for unknown reasons such shells are generally rare among extant gastropods.

Side view of a planorbid shell (left) and its cross section (right), showing the protoconch in the center.

1. Say, T. 1817. Journal of the Academy of Natural Sciences of Philadelphia, 1:17-18.
2. Say, T. 1821. Journal of the Academy of Natural Sciences of Philadelphia, 2:149-179.
3. There are a few other species of Helicodiscus that also have planispiral shells.
4. Raup, D.M. & Stanley, S.M. 1978. Principles of Paleontology. 2nd ed.

03 June 2005

Friday nite's beer review: Efes from Turkey

Efes is a pilsen (pilsner, pilsener) beer manufactured in Turkey since 1969 by the Anadolu Efes Brewery (www.efespilsen.com.tr - in Turkish). It has a very light aroma and a barely perceptible flavor. I normally prefer more flavorful beers, but I don't mind an occasional break from the ales and porters for a bottle of Efes.

Efes is what the Turks call Ephesus, the famed antique city in southwestern Turkey. George Bean1 mentions the drinking of wine in the antiquity in what is now western Turkey, but I am not aware of any references to beer drinking.

Ephesus used to be a harbor town situated towards the end of a long and relatively narrow bay, but the alluvium brought by the river Cayster (now Küçük Menderes) gradually filled up the bay, eventually isolating Ephesus from the Aegean Sea. The Ephesians tried very hard to keep their harbor open, but failed at the end. I will have more on that in another post.


Ephesus, Temple of Hadrian

Note added Monday nite: Last weekend's beer reviewed at Webiocosm was Guinness Draught. Do you know how to pronounce it?

1. Bean, G.E. 1979. Aegean Turkey. Ernest Benn, London.

02 June 2005

A friend of fungi: Philomycus flexuolaris

In 1820, the eccentric naturalist Constantine Samuel Rafinesque, then a professor of botany and natural history at the University of Transylvania in Lexington, Kentucky, erected a new genus for a group of slugs native to the northeastern U.S.1

["N. G." = New Genus.]

He also described four new species of Philomycus, including the one below.


As Pilsbry2 noted, the slug Binney3 illustrated as Tebennophorus caroliniensis in his 1857 compilation of the terrestrial mollusks of the U.S. was actually Rafinesque's Philomycus flexuolaris.


Although brief, Rafinesque's description of the color of Philomycus flexuolaris and the patterns on its back are fairly accurate. I saw several of these slugs last weekend during the BioBlitz at New Germany State Park in Garrett Co., Maryland. My specimen in the photograph below was about 65 mm long, within Rafinesque's range. Rafinesque's statement that Philomycus "differs from Limax by no visible mantle" indicates that he didn't realize that in these slugs the mantle covers the entire back.


1. Rafinesque, C.S. 1820. Annals of Nature, First annual number, p. 10. Philadelphia.
2. Pilsbry, H.A. 1948. Land Mollusca of North America (north of Mexico ). Volume 2, Part 2, p. 758. Academy of Natural Sciences, Philadelphia.
3. Binney, A. 1857. The terrestrial air-breathing mollusks of the United States. Vol. III. Little Brown & Co.

01 June 2005

Urban nature, or the lack thereof

An editorial, Nature in the Metropolis, by Peter Crane and Ann Kinzig in last week’s Science brings attention to an increasingly important issue: the protection of nature versus the seemingly endless growth of cities. But, first, what seems to be good news: “In some respects, cities are good for the environment. They concentrate half the world’s population on about 2% of Earth’s land surface”. I suppose it is indeed better to have one mega-city of, say, 10 million people than 1000 cities each with 10,000 people, provided that the mega-city takes up much less area than the combined areas of 1000 cities. If the city dwellers always remained in their cities, things would even be better. The problem is that we all want to go on vacation, which means that even if we could substitute one mega-city for 1000 small cities, we would still have to build somewhere else 1000 hotels, resorts and vacation villages for all those urbanites.

Another downside to letting cities grow very big is that not only do they grow vertically—which is fine—but also horizontally. And often, the land a city is swallowing may be the only remaining habitat of some unique, endemic wildlife. I have touched upon this subject in relation to the growth of the Turkish city of Istanbul, the population of which recently reached 10 million1, 2.

What ends up happening is that the city dwellers become alienated to nature: “A further subtle but important consequence of increased urbanization is that most of the world’s people will have much of their direct contact with nature in an urban rather than rural setting.” It’s worse than that: people will “experience” nature only through TV shows. This has actually been going on for quite some time.

How do we expect kids who have never set foot in a forest to grow up to be conservationists?

1. Örstan, A. 2004. Cemeteries as refuges for native land snails in Istanbul, Turkey. Tentacle, No. 12, pp. 11-12. pdf
2. Örstan, A. 2005. The status of Pomatias elegans in Istanbul, Turkey. Tentacle, No. 13, pp. 8-9.