30 March 2011

Hungry vulture on the road

My wife photographed this black vulture with her phone today. It was eating the remains of a roadkill, possibly a gray squirrel. Apparently, it was quite careless about the traffic and would only take a step or 2 away from the median line whenever a car passed by and then return to its lunch. It must have been quite hungry.

It is interesting that these vultures have not evolved the habit of picking up small carcasses and carrying them away to safer spots.

Previous vulture post was here.

29 March 2011

Every tail tells a story


Marissa Cat was watching something outside the window this morning. After I filmed her, I peeked out but couldn't see anything of interest. Marissa's tail was still excited though.

28 March 2011

Fruit flies, biological species and hybrid zones

Hybrids form when 2 closely related species mate in a contact zone where their distribution ranges overlap. Usually, hybrids are sterile and so the 2 species maintain their identities. My one and so far only (minor) contribution to the literature on hybridization was the subject of this post.

Today at the University of Maryland I had the pleasure to attend a seminar by a major player in the field, Jerry Coyne of the University of Chicago. Dr. Coyne's research is about 2 species of fruit flies, one of which, Drosophila santomea, lives on the island of São Tomé, while the other, D. yakuba, lives on the mainland Africa and also on the same island. Apparently, D. santomea descended from colonizing individuals of the mainland species cast on the island several tens of thousands years ago. Subsequently, when more flies arrived from the mainland, especially after the Portuguese came and cleared the low elevation forests, the allopatric speciation was more or less complete. Hybrids do form, but the male flies are sterile. The biological species concept, defined by Coyne as "a group of interbreeding organisms that shows substantial reproductive isolation from other such groups in nature", holds for each fly species.

All is well until we take a closer look at the hybrid zones up the mountain on São Tomé. It turns out that there is not one, but 2 hybrid zones. The 1st one is where it is supposed to be, between the ranges of the low elevation D. yakuba and the high elevation D. santomea. The 2nd one is, however, located where there should be no hybrids; actually no flies, because it's too cold: near the peak of the mountain. Moreover, in both hybrid zones only male hybrid flies have so far been found, although female hybrids exist in laboratory populations.

Mysteries remain and our need to unravel them is what makes doing and learning about science fun. My lack of understanding of most of the genetics behind Dr. Coyne's research did not prevent me from enjoying his talk.

26 March 2011

How to write a scientific paper: a discourse on discussions

It is customary for scientific papers to have a "discussion" section. This is different than a review of the relevant literature and should not be confused with it. The literature review, often excessively long and destined to be skipped in its entirety by the readers, is usually placed as an introduction to the paper. The discussion section, on the other hand, comes after the "results" section.

What is the purpose of the discussion section?

The relevant dictionary definition of discussion is: "A formal discourse on a topic; an exposition." Whereas discourse is defined as "A formal, lengthy discussion of a subject, either written or spoken." So, the discussion section of a paper literally discusses the findings reported elsewhere in the paper. Let me expound that a bit more.

1. The discussion section of a manuscript should try to explain the results within a theoretical framework accepted by the general scientific community.

If the results do not fit into an accepted theory, then there are 3 possibilities: 1. the results do indeed fit into an accepted theory, but the author doesn't know how to do it; 2. the results are wrong, because either the experiments or the observations were not done properly and therefore, they should not be published; 3. the accepted theory or theories are wrong, which may mean that the results are truly revolutionary. The last case is a rare happening. But when the author is convinced of it, the discussion section of the manuscript should boldly declare the existing theories kaput and, if possible, devise a better theory that indeed explains the results.

2. When applicable, the discussion section of a manuscript should explain, or provide clues towards a future explanation of, phenomena that were unexplainable before the results presented in the manuscript were obtained. Therefore, these results also suggest how an initially small increase in the size of the foot could have initiated the evolution of slugs from snails.

3. Note that some scientific explanations are actually predictions. I think my results will also explain in the future this presently inexplicable observation.

Therefore, when applicable, the discussion section of a manuscript should make a justifiable prediction or two towards the clarification of present unknowns. In lieu of a prediction, the discussion could pave the way for future research. One of the shortest papers I have written (about a new record of the snail Vertigo pusilla in Turkey) ended with a 3-sentence "discussion" that fit my finding within the previous records and gave a direction for future surveys.

The southern border of the distribution range of V. pusilla is not known (Pokryszko, 1990). The present record and those in Schütt (2001) establish the definite presence of the species in a relatively narrow region restricted to northwest Turkey. It remains to be determined if the species is present further south and east in the country.
I am a big supporter of short scientific papers. All scientists should strive to trim off the needlessly long introductions, methodologies, discussions, conclusions from our papers. Even the results sections of manuscripts should have no more than one or two essential experiments or observations. If you need to do 20 different experiments or observations to prove one point, then you are probably missing one crucial test that would be enough.

More can be written on this subject, but I will leave further discussions to future posts.

I was prompted to write this post by the poorly written discussion section, in addition to poorly written everything else, of a manuscript I have been peer-reviewing. I will probably include some of the ideas presented here in my anonymous review report. The author, if he/she ever does an Internet search on the writing of scientific manuscripts, may eventually figure out that it was I who rejected the manuscript for publication.

24 March 2011

Eobania vermiculata gets bigger

As explained in yesterday's post, I am busy measuring shells of the land snail Eobania vermiculata. Actually, I spend only about a half an hour a day doing that, measuring 8 to 10 shells at each session.

Among the shells I measured tonight, there was a nice surprise. One of the only 3 shells collected at one locality turned out to be the largest Eobania shell I have measured so far. Its diameter, 34.8 mm, is almost the same as the maximum of 35 mm George Tryon gave in the Manual of Conchology (vol. 4, 1888). Who knows how accurate Tryon's measurements were anyway.

The current record holder is the leftmost shell in the picture below (unfortunately, it has a large hole in its spire).

Interestingly, the middle shell in the picture is the 15th smallest shell among the total of 96 shells I have measured. So here we have 2 shells from one locality representing each end of our distribution.

Expect more on this topic.

23 March 2011

Eobania vermiculata in my mind

Eobania vermiculata and its varieties from the Manual of Conchology (vol. 4, 1888).

I have been measuring shells of the land snail Eobania vermiculata. My purpose is to have a better understanding of the dimensional variability of the species.

In the Manual of Conchology (vol. 4, 1888), George Tryon gave the shell diameters of Eobania vermiculata as 30-35 mm. These numbers probably represented the range of average sized shells. In comparison, Kerney & Cameron in A field guide to the land snails of Britain and North-west Europe (1979) gave the diameter range as 22-30 mm, undoubtedly a truer range.

So far I have measured 78 shells collected from different locations in Turkey. The smallest and the largest adult shells were 24.8 and 31.9 mm, respectively. My largest shell is outside the upper end of the range Kerney & Cameron gave, but is smaller than Tryon's largest. On the other hand, I still have to find something as small as the lower limit of Kerney & Cameron. I have probably about 40 more shells to measure and also one lot of more than 100 shells from one locality. So these numbers are likely to change.

The measurements of the 78 shells also indicate that the variability of the combined sample is within the limits of the variability of large enough single lots. That is an interesting result about which I will write more in the future.

The next post in this series is here.

20 March 2011

Bootleg transactions of the 13th MAM meeting

The 13th meeting of the Mid-Atlantic Malacologists took place yesterday at the Delaware Museum of Natural History (DMNH) in Wilmington, Delaware. There were about 32 attendees, one of the highest numbers in recent years.

Here are the speakers in the order they spoke and the not-more-than-two-sentence summaries of their talks.

  • Marla Coppolino (New York): Marla played the rasping sounds of her pet snails' radulae recorded while they were eating a carrot. The snails were Mesodon zaletus.

  • Charlie Sturm (Carnegie Museum of Natural History, Pittsburgh): Charlie, the current president of the American Malacological Society, is organizing the 77th meeting of the Society to take place 23-38 July 2011 in Pittsburgh, PA. Be there!

  • Paul Callomon (Academy of Natural Sciences, Philadelphia): The mollusk collection of the ANS is being recataloged with the help of a voice-recognizing software.

  • Paula Mikkelsen (Paleontological Research Institution, Ithaca): Paula presented an overview of the history of publishing in malacology. In 1959, 485 papers containing the phrase "mollus" were published, while in 2009 their number had gone up to 2058.

  • Tim Pearce (Carnegie Museum of Natural History, Pittsburgh): Tim presented his ideas on the evolution of slugs from snails. Why is it good to be a semi-slug?

  • Lynn Dorwaldt (Wagner Free Institute of Science, Philadelphia): History of the Wagner Free Institute of Science and also the bivalves from Isaac Lee's collection that are kept at the Institute. Some 19th century malacology books from the Institute's library were passed around.

  • William Wagner founded the science institute named after him. He also gave public lectures on conchology.

  • Robert Robertson (Academy of Natural Sciences, Philadelphia): According to Gunner Thorson's (1950) shell apex theory, protoconch morphologies reflect modes of larval development. Robert's research shows that the theory doesn't apply to the Pyramidellidae.

  • Tom Grace (Pennsylvania): New records of the freshwater mussel Margaritifera in the headwaters of the Schuylkill River.

  • Aydin Örstan (Carnegie Museum of Natural History, Pittsburgh): I presented my half-baked ideas on the breathing anatomy of semi-terrestrial rissooids snails.

  • Here I am in front of a giant Assiminea succinea.

  • Bill Fenzan (Virginia): The 1st International Cone Meeting was in Stuttgart, Germany in October 2010. The next meeting will be in La Rochelle, France in September 2012 (for more info see The Cone Collector).

  • Makiri Sei (Academy of Natural Sciences, Philadelphia): Makiri talked about her ongoing project with Gary Rosenberg on the phylogeny of Jamaican Annulariidae based on DNA sequences.

  • Kevin Ripka: Kevin, a birder who recently got interested in snails, is developing an iPhone app for northeast U.S. land snails.

  • Adam Baldinger (Museum of Comparative Zoology, Harvard University): Adam talked about the various mollusk models at MCZ among which are a large number glass mollusks and other invertebrates made by the Leopold and Rudolf Blaschka.

  • Megan Paustian (Carnegie Museum of Natural History, Pittsburgh): Megan talked about the ecology and species of the slugs in the genus Meghimatium in Japan. She also showed slides from her trip there.

  • Francisco Borrero (Cincinnati Museum Center): The taxonomy and biogeography of the Orthalicoidea from Colombia and adjacent areas.

  • Once again I will take this opportunity to thank to Liz Shea, the curator of mollusks at the DMNH and Leslie Skibinski, the collection manager, for organizing this wonderful meeting. I am already looking forward to next year's gathering.

    The bootleg transactions of the 12th MAM meeting are here.

    19 March 2011

    Juvenile Leptoxis carinata

    Our reader Thomas of Baltimore sent these slightly blurry pictures of snails with impressive keeled shells and asked for an identification. He had found them in the Little Gunpowder River north of Baltimore City. I don't normally work with freshwater mollusks and I don't know much about them. But I could see what looked like an operculum on the foot of one of the snails on the left, which indicated they were not pulmonates. At the same time, their looks suggested they were juveniles—often a complicating factor when one is trying to identify a species.

    I skimmed thru the pictures in The Freshwater Gastropods of North America to no avail. So I forwarded the pictures to our freshwater expert Rob Dillon. He is a contributor to FWGNA and also writes the blog Freshwater Gastropods of North America.

    Rob quickly identified the snails as juvenile Leptoxis carinata, which is indeed an operculated species. It turned out that the adult shells are not keeled (carinated) and therefore look very different than juveniles. Hence my failure to find them among the pictures in FWGNA.

    14 March 2011

    How slugs are turning a mountain into dust

    The fellow local blogger Callan Bentley who writes the very informative geology blog Mountain Beltway organized a hike up the nearby Sugarloaf Mountain this past Saturday. My wife and I considered joining them, but for some insane reason they were adamant about starting at 9 am when we would still be waiting for our coffee to brew. So we missed the trip. Hopefully, there will be more opportunities in the future to join Callan in the field during more reasonable hours of the day.

    Meanwhile, Callan e-mailed this morning some interesting pictures he had taken on Sugarloaf during the hike. They show what appear to be gastropod feeding tracks in the layers of algae (cyanobacteria) covering the surfaces of rocks.

    I suspect the tracks were made by slugs. Compare them with the examples I have in the posts here, here and here.

    The underlying rocks are, according to Callan's post, quartzite.

    Now, I draw your attention to the following papers:

    Danin, A. 1986. Patterns of corrosion and abrasion induced by Mediterranean land snails on limestone rocks. Malacolological Review 19:91.

    Shachak, M., Jones, C.G. & Granot, Y. 1987. Herbivory in rocks and weathering of a desert. Science 236:1098-1099.

    Jones, C.G. & Shachak, M. 1990. Fertilization of desert soil by rock-eating snails. Nature 346:839-841.

    The snails mentioned in the cited papers apparently eat the limestone rocks to extract the endolithic lichens* that are their actual food. The result of this phenomenon is the slow conversion of rocks into sand. But this is somewhat different than what was observed on Sugarloaf Mountain. On Sugarloaf the slugs are eating the algae that grow externally on the rock surface. Moreover, quartz is much harder than limestone (calcite) on the Mohs Scale of mineral hardness. Therefore, the title of this post notwithstanding, I actually doubt the slugs could inflict any significant damage to the rocks of Sugarloaf Mountain.

    *Lichens that grow inside, but near the surface of rocks.

    13 March 2011

    Not exactly a hermit crab

    I put several sea shells of uncertain provenance out on my deck several months ago. Their sole intended function was to enliven the otherwise drab wooden railing. However, certain arthropodous denizens of the backyard, distantly related to the hermit crabs of the sea and the seashore, appear to have developed a liking to the shells.

    When I lifted one snail shell up yesterday, I inadvertently revealed the hideout of a spider of some sort.

    I don't know if the spider was using the shell to hide from unsuspecting prey or its own predators or simply as a shelter from the elements. The correct answer may be all of the above.

    11 March 2011

    Simroth's snail-imitating moth

    Heinrich Simroth was a German malacologist of some distinction. Once he published a short paper* about the larva of a coleophorid moth whose case he thought resembled the shell of a clausiliid snail.

    Here are Simroth's drawings of the moth larva.

    According to BugGuide, coleophorid larvae from the second instar onward carry a "portable case" around them, which they make using silk and/or plant material.

    Simroth also thought that the larva's mimicry protected it from predatory birds: "I think it is clear that the whole arrangement is very effective and likely to deceive small birds frequenting the rocks for feeding upon insects."

    Simroth did not identify the moth. I don't know if anything more substantial on the presumed mimicry of these moths has since been written.

    *Simroth, H. 1901. Clausilia mimicked by a microlepidopteron. Journal of Malacology 8:33-34.

    10 March 2011

    Worrying about Truncatellina

    The leftmost shell is about 2.1 mm long.

    These land snail shells are from Istanbul, Turkey. I've been trying to identify them for some time now. They are a Truncatellina species, probably either T. rothi or T. cyclindrica. But, which one?

    I don't yet lose sleep over these things. But I still need to know the species I have before I can finish a manuscript I am writing.

    09 March 2011

    The man with botanical eyes

    These are impromptu pictures we've been taking while grocery shopping since last fall. It all started when I noticed the bottoms of kiwis resembled eyes. There will probably be a 2nd series in the future as other fruits and vegetables attract my attention.

    The readers who are my friends on facebook will recognize them as my profile pictures during the past several months.

    The man with kiwi eyes

    The man with red pear eyes

    The man with tangerine eyes

    The man with onion eyes

    07 March 2011

    What is a gill?

    Sometimes one encounters useful tidbits of insight in unexpected places. Last night, while relaxing in bed with The Insects by Gullan & Cranston* (2005), I came across a characterization of a gill. In their discussion of the caudal lamellae of an aquatic insect larva, they list these criteria for an organ to be considered a gill:

    1. Possession of a large surface area.
    2. Being moist and vascular.
    3. Being able to be ventilated.
    4. Being responsible normally for 20-30% of oxygen uptake.

    The requirement that a gill be moist is almost redundant, since gills are possessed mostly by aquatic animals. In other words, they are wet anyway. But let us keep it, for as I mentioned in this post, gills and lungs need to be kept wet to keep gas exchange going.

    The underlying anatomies of a gill and a lung are the same: a large, wet area overlaying blood vessels and exposed to an oxygen-rich medium. Therefore, these criteria also ably to a lung. Go to this post for more on this topic.

    *Yes, my bedtime reading may be unusual by ordinary standards.

    06 March 2011

    A face in the woods

    Cut but still complacent.

    04 March 2011

    Snails in the local Asian store

    These appear to be a littorinid species. The label below the tray said they were "mud snai".

    The members of the family Littorinidae are intertidal, semi-terrestrial snails whose ancestors stopped short of evolving to be fully terrestrial. They were the subjects of two old posts here and here.

    In the next tray were these larger snails labeled "shell conch". My ignorance of the taxonomy of most marine gastropods prevents me from attaching even a family name to them.

    03 March 2011

    Let's show some respect for mad scientists

    During my 30-year career as a scientist, I have come across about a half a dozen Ph.D. recipients who were implausibly and alarmingly unscientific and unintellectual. They had somehow fallen or been pushed thru the cracks of their respective Ph.D. granting schools. Those characters were living proofs that a Ph.D. does not necessarily turn a recipient into a scientist. The corollary is that to become a scientist one doesn't need a Ph.D.

    If there were a way to measure the scientistness of scientists, I would suspect that the distribution of the measure for a large number of scientists would follow a normal curve. The half a dozen dullards, and others like them, would be in the left-hand tail of the bell curve.

    Who would be in the right-hand tail? The Nobel laureates and the like? No. The mad scientists.

    The proverbial mad scientist is a highly scientific person, with or without a Ph.D., but with certain unscrupulous motives that overcome or dictate their scientific curiosities. Hence, they are in the right-hand tail of the distribution of scientistness.

    The real question is, would we rather have a mad scientist than a nonintellectual Ph.D. who has no idea what it is all about?

    The mad scientist Kavon (played by David Opatoshu) making his point in the episode Alexander the Greater Affair (part 2) of the mid-1960's TV series The Man from U.N.C.L.E. The U.N.C.L.E. agent Napoleon Solo had just interrupted Kavon's attempt to mummify Solo's partner Illya Kuryakin (in the background).

    01 March 2011

    Snail dispersal by cars - Part 2

    Published evidence for the passive dispersal of land snails, especially of alien species, on cars was the subject of this post. The process is simple: if a car is parked at a spot where there are active snails, some of them may climb on the car and later go wherever the car happens to go.

    Here is a piece of evidence that this indeed happens. These pictures of a snail was taken by my friend Selim Dorak on his car in the city of Antalya in southern Turkey. The car was in the parking lot of a store when Selim first saw the snail. He then drove with the snail on the car to his house and thereby demonstrated that dispersal of snails by car, at least over short distances, is possible.

    The snail seems to have been a species in the family Hygromiidae. Another possibility is that it was a juvenile Helix, sp. but they usually don't have such pointed spires.