jul 2008
Beauty is in the eye of the beholder
29-07-2008 13:27
Dissecting and illustrating a snail may not be as
easy as it seems, especially if you haven't practiced
it anymore for so many years :-)
However, after a long day in the lab I managed to produce this drawing:
It is reasonably nice, but perhaps not more than just that. Compare it e.g. to the illustrations that my friend Jaap Vermeulen uses for his papers, like this one:
Lesson for this day: illustrating is a profession. But beauty is in the eye of the beholder...
However, after a long day in the lab I managed to produce this drawing:
It is reasonably nice, but perhaps not more than just that. Compare it e.g. to the illustrations that my friend Jaap Vermeulen uses for his papers, like this one:
Lesson for this day: illustrating is a profession. But beauty is in the eye of the beholder...
Tepui fever
27-07-2008 16:35
When I recently got some information on the habitats
of snails from Venezuelan Guayana, I was curious to
find some more details on the plants and scenery.
Although I have the introductory volume of the Flora
of the Venzuelan Guayana, I wanted to see some more.
Quickly I discovered the important role of
Charles Brewer-Carías
as an explorer of this area.
Digging further I hit upon the site on a Czech speleologist who has been part of several expeditions, partly with Brewer-Carías. They have discovered several cave systems in the tepuis. Look here for some astonishing photography (follow the links to the galleries). Marvelous!
It really gives me what they call the tepui fever...
Digging further I hit upon the site on a Czech speleologist who has been part of several expeditions, partly with Brewer-Carías. They have discovered several cave systems in the tepuis. Look here for some astonishing photography (follow the links to the galleries). Marvelous!
It really gives me what they call the tepui fever...
The end of theory: the end of taxonomy?
26-07-2008 11:24
Provocative. That's the least you could say.
Last month Chris Anderson wrote an essay on his blog called The End of Theory: The Data Deluge Makes the Scientific Method Obsolete. As the editor in chief of Wired, he became known with his story about The Long Tail in business.
In his new article his thesis is that the prolific availability of data and the ever evolving computing capabilities will stimulate a different approach to science. One in which pattern recognizing is more important that meticulously analyzing data. He call it the Petabyte Age.
"At the petabyte scale, information is not a matter of simple three- and four-dimensional taxonomy and order but of dimensionally agnostic statistics. It calls for an entirely different approach, one that requires us to lose the tether of data as something that can be visualized in its totality. It forces us to view data mathematically first and establish a context for it later."
In his view this requires a complete different approach to science, discarding the idea that you first have a theory, derive a hypothesis from it and test it to falsify or not.
"This is a world where massive amounts of data and applied mathematics replace every other tool that might be brought to bear. Out with every theory of human behavior, from linguistics to sociology. Forget taxonomy, ontology, and psychology. [...] Now biology is heading in the same direction. The models we were taught in school about "dominant" and "recessive" genes steering a strictly Mendelian process have turned out to be an even greater simplification of reality than Newton's laws. The discovery of gene-protein interactions and other aspects of epigenetics has challenged the view of DNA as destiny and even introduced evidence that environment can influence inheritable traits, something once considered a genetic impossibility. In short, the more we learn about biology, the further we find ourselves from a model that can explain it.
There is now a better way. Petabytes allow us to say: "Correlation is enough." We can stop looking for models. We can analyze the data without hypotheses about what it might show. We can throw the numbers into the biggest computing clusters the world has ever seen and let statistical algorithms find patterns where science cannot.
The best practical example of this is the shotgun gene sequencing by J. Craig Venter. Enabled by high-speed sequencers and supercomputers that statistically analyze the data they produce, Venter went from sequencing individual organisms to sequencing entire ecosystems. In 2003, he started sequencing much of the ocean, retracing the voyage of Captain Cook. And in 2005 he started sequencing the air. In the process, he discovered thousands of previously unknown species of bacteria and other life-forms.
If the words "discover a new species" call to mind Darwin and drawings of finches, you may be stuck in the old way of doing science. Venter can tell you almost nothing about the species he found. He doesn't know what they look like, how they live, or much of anything else about their morphology. He doesn't even have their entire genome. All he has is a statistical blip — a unique sequence that, being unlike any other sequence in the database, must represent a new species.
Can you imagine snails as blips? Indeed, the end of taxonomy...
In a series in NYT devoted to Darwin, Olivia Judson writes that "I’m not sure he’d enjoy analyzing DNA sequences — he might find it a bit too abstracted from the living organism — but I think he’d be delighted to learn the results. I think he would be shocked by how much we know about the so-called model organisms — worms, toads, fruit flies, mice, humans and the bacterium E. coli — and how little we know about everything else. And I think he’d be startled by the nature of scientific research — the scale of the enterprise, the cost, the pressures to publish and the degree of specialization that results. His brand of science — 20 years of thinking about a problem before publishing — could not be done today."
Agreed, but that doesn't mean that we cannot take advantage of new tools. We should only do so wisely.
Back to Anderson and his provocative article. He admitted in a radio talk as a magazine editor that they sometimes pump up their headlines. Sounds familiar, huh?
What he meant to say in his article, was that with the current day possibilities we have a new scientific tool which challenge the tradition of first having the theory and then the experiment.
That sounds more reasonable. Admittedly, data crunching will give us new insights. But we should forget to maintain a holistic viewpoint. The overview is as import as the nitty-gritty details. If you don't know if the species was identified correctly, a whole database on biogeography may be producing odd data. Like can be seen sometimes on GBIF... Bulimulidae in Asia??
The bottom line is, what was correctly put forward in an article of The Economist:
"a species is what a taxonomist says it is. Evolution often fails to produce the clear divisions that human thought in general, and the law in particular, prefers to work with. It therefore behoves taxonomists to be honest. If they debase their currency, it will ultimately become valueless. Linneaus the economist would have known that instinctively".
Last month Chris Anderson wrote an essay on his blog called The End of Theory: The Data Deluge Makes the Scientific Method Obsolete. As the editor in chief of Wired, he became known with his story about The Long Tail in business.
In his new article his thesis is that the prolific availability of data and the ever evolving computing capabilities will stimulate a different approach to science. One in which pattern recognizing is more important that meticulously analyzing data. He call it the Petabyte Age.
"At the petabyte scale, information is not a matter of simple three- and four-dimensional taxonomy and order but of dimensionally agnostic statistics. It calls for an entirely different approach, one that requires us to lose the tether of data as something that can be visualized in its totality. It forces us to view data mathematically first and establish a context for it later."
In his view this requires a complete different approach to science, discarding the idea that you first have a theory, derive a hypothesis from it and test it to falsify or not.
"This is a world where massive amounts of data and applied mathematics replace every other tool that might be brought to bear. Out with every theory of human behavior, from linguistics to sociology. Forget taxonomy, ontology, and psychology. [...] Now biology is heading in the same direction. The models we were taught in school about "dominant" and "recessive" genes steering a strictly Mendelian process have turned out to be an even greater simplification of reality than Newton's laws. The discovery of gene-protein interactions and other aspects of epigenetics has challenged the view of DNA as destiny and even introduced evidence that environment can influence inheritable traits, something once considered a genetic impossibility. In short, the more we learn about biology, the further we find ourselves from a model that can explain it.
There is now a better way. Petabytes allow us to say: "Correlation is enough." We can stop looking for models. We can analyze the data without hypotheses about what it might show. We can throw the numbers into the biggest computing clusters the world has ever seen and let statistical algorithms find patterns where science cannot.
The best practical example of this is the shotgun gene sequencing by J. Craig Venter. Enabled by high-speed sequencers and supercomputers that statistically analyze the data they produce, Venter went from sequencing individual organisms to sequencing entire ecosystems. In 2003, he started sequencing much of the ocean, retracing the voyage of Captain Cook. And in 2005 he started sequencing the air. In the process, he discovered thousands of previously unknown species of bacteria and other life-forms.
If the words "discover a new species" call to mind Darwin and drawings of finches, you may be stuck in the old way of doing science. Venter can tell you almost nothing about the species he found. He doesn't know what they look like, how they live, or much of anything else about their morphology. He doesn't even have their entire genome. All he has is a statistical blip — a unique sequence that, being unlike any other sequence in the database, must represent a new species.
Can you imagine snails as blips? Indeed, the end of taxonomy...
In a series in NYT devoted to Darwin, Olivia Judson writes that "I’m not sure he’d enjoy analyzing DNA sequences — he might find it a bit too abstracted from the living organism — but I think he’d be delighted to learn the results. I think he would be shocked by how much we know about the so-called model organisms — worms, toads, fruit flies, mice, humans and the bacterium E. coli — and how little we know about everything else. And I think he’d be startled by the nature of scientific research — the scale of the enterprise, the cost, the pressures to publish and the degree of specialization that results. His brand of science — 20 years of thinking about a problem before publishing — could not be done today."
Agreed, but that doesn't mean that we cannot take advantage of new tools. We should only do so wisely.
Back to Anderson and his provocative article. He admitted in a radio talk as a magazine editor that they sometimes pump up their headlines. Sounds familiar, huh?
What he meant to say in his article, was that with the current day possibilities we have a new scientific tool which challenge the tradition of first having the theory and then the experiment.
That sounds more reasonable. Admittedly, data crunching will give us new insights. But we should forget to maintain a holistic viewpoint. The overview is as import as the nitty-gritty details. If you don't know if the species was identified correctly, a whole database on biogeography may be producing odd data. Like can be seen sometimes on GBIF... Bulimulidae in Asia??
The bottom line is, what was correctly put forward in an article of The Economist:
"a species is what a taxonomist says it is. Evolution often fails to produce the clear divisions that human thought in general, and the law in particular, prefers to work with. It therefore behoves taxonomists to be honest. If they debase their currency, it will ultimately become valueless. Linneaus the economist would have known that instinctively".
Why habitat information matters
24-07-2008 14:36
While working on a paper about carinate species, I
found pictures of some species on the internet. There
has been some discussion in the literature about what
causes carination, and the habitat seems one of the
factors in play. Therefore, I found it interesting
that the site gave some habitat information on one of
the species for which I didn't have data yet. It said
the species was collected "on rocks in a bushed
area". Especially the association with rocks
interested me.
Luckily, the site mentioned also who had collected the specimens. I decided to contact the collector, a befriended couple who have travelled a lot in Latin America and whose collecting data are always very precise and trustworthy. To my surprise, the answer I got was only partly corroborating. The locality was right but the habitat not! Instead collected on rocks, the specimens had been found as subfossils in a desert-like area. Quite a difference and not without importance.
So, the lesson I learned here is: if you can, always consult the original source.
Luckily, the site mentioned also who had collected the specimens. I decided to contact the collector, a befriended couple who have travelled a lot in Latin America and whose collecting data are always very precise and trustworthy. To my surprise, the answer I got was only partly corroborating. The locality was right but the habitat not! Instead collected on rocks, the specimens had been found as subfossils in a desert-like area. Quite a difference and not without importance.
So, the lesson I learned here is: if you can, always consult the original source.
From one canopy to another
21-07-2008 20:21
Those bromeliads put me on track of this great website: Mongabay. Devoted to rain-forests throughout the world, I found it highly informative and worthwhile. Besides some general sections, e.g. on indigenous people and biodiversity, there is a wealth of information on deforestation and data per country. Data sources are e.g. FAO, UNEP and WorldWatch Institute, but there is a detailed list of references for each section. And, of course, also a section on the canopy...including bromeliads.
It provides also a wealth of pictures, both from undisturbed forests and from deforestation. Biodiversity pictures are from plants, birds and insects. Snails are missing, but I have to admit, you must be keen on them to spot them and the conditions have to be right :-)
And finally the links section is an endless resource for other rainforest topics, blogs and news.
Knowing that this is one-person endeavour, Mr. Butler... chapeau!
Bromeliads, beetles and snails
21-07-2008 10:52
Bromeliads belong to a diverse group of flowering
plants, which in part are epiphytic. There are around
3000 species known from the Neotropics. Growth forms
vary with environmental conditions, but typically
there are a collection of wide, linear, straplike
leaves with inflated bases that overlap to construct
a tight rosette. These rosettes often form watertight
tanks that can hold rainwater for many days.
Many of these tank bromeliads live in montane (cloud) forest where they can usually be found in the canopy. Out of reach of the "normal" biologist, as you need to climb high if you want to make observations. Yet they are known habitats for insects, frogs, epigeic earthworms, ostracods and also are a foraging site for birds.
Snails have also been associated with bromeliads. Basically there are two groups: one on Tillandsia sp. and one on (probably) other tank bromeliad genera. The first groups concerns Bostryx species from Peru, e.g. B. bromeliarum (Pilsbry, 1930) and the B. spiculatus-group.
The second group comprises Simpulopsis species, and although most have been described without mentioning of their habitat, given their locations and the association with bromeliads of some of them, I have a strong suspicion that several species might be associated with tank bromeliads. We know at least that S. simulus (Morelet, 1851) and S. magnus Thompson, 1957 have been found in bromeliads. The same might be true for S. corrugatus Guppy, 1866 from Trinidad and several species reported from the east coast of Brazil (Atlantic Forest, or what is left of it).
Enough of this rambling on bromeliads and snails... What about the beetles?
Merely by chance I stumbled upon the recent paper by Balke et al.* on the association between aquatic beetles and tank bromeliads. They studied a group of beetles that occurs in small water bodies in tropical forests, but a small subset of them is specialized to the water reservoirs of tank bromeliads. Extensive phylogenetic work revealed that the origin of one of the lineages was estimated to be comparable to that of the tank bromeliads. The other two lineages that are associated with these plants are thought to be more recent expansions into the tank water habitat.
The evolution of these canopy communities is far from being understood and leaves several areas open for further research. Snails being but one of them.
Reference:
Balke, M., Gómez-Zurita, J., Ribera, I., Vilora, A., Zillikens, A., Steiner, J., García, M, Hendrich, L. & Vogler, A.P. (2008). Ancient associations of aquatic beeles and tank bromeliads in the Neotropical forest canopy. Proceedings of the National Academy of Sciences of the United States of America, 105, 6356-6361.
Many of these tank bromeliads live in montane (cloud) forest where they can usually be found in the canopy. Out of reach of the "normal" biologist, as you need to climb high if you want to make observations. Yet they are known habitats for insects, frogs, epigeic earthworms, ostracods and also are a foraging site for birds.
Snails have also been associated with bromeliads. Basically there are two groups: one on Tillandsia sp. and one on (probably) other tank bromeliad genera. The first groups concerns Bostryx species from Peru, e.g. B. bromeliarum (Pilsbry, 1930) and the B. spiculatus-group.
The second group comprises Simpulopsis species, and although most have been described without mentioning of their habitat, given their locations and the association with bromeliads of some of them, I have a strong suspicion that several species might be associated with tank bromeliads. We know at least that S. simulus (Morelet, 1851) and S. magnus Thompson, 1957 have been found in bromeliads. The same might be true for S. corrugatus Guppy, 1866 from Trinidad and several species reported from the east coast of Brazil (Atlantic Forest, or what is left of it).
Enough of this rambling on bromeliads and snails... What about the beetles?
Merely by chance I stumbled upon the recent paper by Balke et al.* on the association between aquatic beetles and tank bromeliads. They studied a group of beetles that occurs in small water bodies in tropical forests, but a small subset of them is specialized to the water reservoirs of tank bromeliads. Extensive phylogenetic work revealed that the origin of one of the lineages was estimated to be comparable to that of the tank bromeliads. The other two lineages that are associated with these plants are thought to be more recent expansions into the tank water habitat.
The evolution of these canopy communities is far from being understood and leaves several areas open for further research. Snails being but one of them.
Reference:
Balke, M., Gómez-Zurita, J., Ribera, I., Vilora, A., Zillikens, A., Steiner, J., García, M, Hendrich, L. & Vogler, A.P. (2008). Ancient associations of aquatic beeles and tank bromeliads in the Neotropical forest canopy. Proceedings of the National Academy of Sciences of the United States of America, 105, 6356-6361.
Photo of the day (17): Drymaeus
19-07-2008 08:59
Roy McDiarmid (Smithsonian Institution) kindly sent
me some information on the expedition to the Cerro de
Neblina massif on the Venezuelan-Brazilian border, in
1984-1985. As it is a remote area that is difficult
to access, it has remained malacologically unknown.
One of the specimens he found there is this Drymaeus species:
One of the specimens he found there is this Drymaeus species:
The Andes
19-07-2008 08:16
Searching the web I came across some specialized
websites that provide access to a further array of
sources. The EvoAndes site is one of them, providing
an overview of different disciplines. Unfortunately
it doesn't seem to be updated anymore and I found
various "dead links".
One of the interesting links that did work, was on páramos in Venezuela, Colombia, Ecuador and Peru. It has a nice set of pictures and references to literature. Another one leads to a specialist site of blueberries (Ericaceae). More lightly is the site on Peruvian orchids, with beautiful photographs. Very nice pictures both of the landscape and of plants in the Andes of Mérida, can be found in the image gallery of the Programa Andes Tropicales.
Unfortunately, I cannot show any pictures from these sites due to copyrights.
One of the interesting links that did work, was on páramos in Venezuela, Colombia, Ecuador and Peru. It has a nice set of pictures and references to literature. Another one leads to a specialist site of blueberries (Ericaceae). More lightly is the site on Peruvian orchids, with beautiful photographs. Very nice pictures both of the landscape and of plants in the Andes of Mérida, can be found in the image gallery of the Programa Andes Tropicales.
Unfortunately, I cannot show any pictures from these sites due to copyrights.
Fragmentation and de-snail-ation
18-07-2008 09:23
The third in a suite on
habitat destruction
and its possible impact on snails. This time Mexico,
where I remember to have travelled through vast
forests in 1974. If I see the map below, I can only
be horrified on what must have been gone.
Almost 50% of the native montane forests existing in 1975 was cleared 25 years later (Cayela et al. 2006). Although deforestation rates are said to be relatively low compared to those in South-East Asia (Mayaux et al. 2005), it is apparent from remote sensing data that large areas of deforestation are to be found in the foothills of the Andes. Agricultural expansion and new settlements are the main drivers.
While some have questioned the deforestation rates, also non-forest habitats are converted at a large extent. Thus, the 1222 species of terrestrial snails on the Red List (Lydeard et al. 2004) seem to me a gross underestimation.
The effects on the snail fauna in the Pacific is well documented (partly invasive species demanded their toll too), but the effect of large-scale deforestation in Latin America seem to have passed unnoticed. To what extent did it affect the land snail fauna? Are some groups more affected than others? Are there examples of 'niche flexibility' that favours survivors?
References:
Cayuela, L., Rey Benayas, J.M. & Echeverria, C. (2006). Clearance and fragmentation of tropical montane forests in the Highlands of Chiapas, Mexico (1975-2000). Forest Ecology and Management, 226, 208-218.
Lydeard, C. et al. (2004). The global decline of nonmarine mollusks. BioScience, 54, 321-330.
Mayaux, P. et al. (2005). Tropical forest cover change in the 1990s and options for future monitoring. Philosophical Transactions of the Royal Society London B, 360, 373-384.
Almost 50% of the native montane forests existing in 1975 was cleared 25 years later (Cayela et al. 2006). Although deforestation rates are said to be relatively low compared to those in South-East Asia (Mayaux et al. 2005), it is apparent from remote sensing data that large areas of deforestation are to be found in the foothills of the Andes. Agricultural expansion and new settlements are the main drivers.
While some have questioned the deforestation rates, also non-forest habitats are converted at a large extent. Thus, the 1222 species of terrestrial snails on the Red List (Lydeard et al. 2004) seem to me a gross underestimation.
The effects on the snail fauna in the Pacific is well documented (partly invasive species demanded their toll too), but the effect of large-scale deforestation in Latin America seem to have passed unnoticed. To what extent did it affect the land snail fauna? Are some groups more affected than others? Are there examples of 'niche flexibility' that favours survivors?
References:
Cayuela, L., Rey Benayas, J.M. & Echeverria, C. (2006). Clearance and fragmentation of tropical montane forests in the Highlands of Chiapas, Mexico (1975-2000). Forest Ecology and Management, 226, 208-218.
Lydeard, C. et al. (2004). The global decline of nonmarine mollusks. BioScience, 54, 321-330.
Mayaux, P. et al. (2005). Tropical forest cover change in the 1990s and options for future monitoring. Philosophical Transactions of the Royal Society London B, 360, 373-384.
Is there a relation with deforestation?
17-07-2008 20:23
It is pure speculation, but just as with
Ecuador,
I suspect a correlation between deforestation and the
"missing re-occurrences" of many once described snail
species in Colombia. One would expect that human
impact on the land cover change must have its toll
also in the malacofauna. Again, I don't know for
sure, but it could be an area for further research.
Here are some data that I found in Etter et al (2006):
With modelling the likelihood of deforestation was predicted and compared with observations using remote sensing techniques. The above map give the results in combination with areas of high biodiversity. But what is also clear from the figure, is the large area of cleared forests (gray). Of course it will depend to some extent in what the new land use is, but arboreal species will prove to be vulnerable (to say the least). It is exactly what I observe in my species list. But no hard data. Yet...
Reference:
Etter, A., McAlpine, C., Wilson, K., Phinn, S. & Possingham, H. (2006). Regional patterns of agricultural land use and deforestation in Colombia. Agriculture, Ecosystems and Environment, 114, 369-386.
Here are some data that I found in Etter et al (2006):
With modelling the likelihood of deforestation was predicted and compared with observations using remote sensing techniques. The above map give the results in combination with areas of high biodiversity. But what is also clear from the figure, is the large area of cleared forests (gray). Of course it will depend to some extent in what the new land use is, but arboreal species will prove to be vulnerable (to say the least). It is exactly what I observe in my species list. But no hard data. Yet...
Reference:
Etter, A., McAlpine, C., Wilson, K., Phinn, S. & Possingham, H. (2006). Regional patterns of agricultural land use and deforestation in Colombia. Agriculture, Ecosystems and Environment, 114, 369-386.
Where one snail goes...?
16-07-2008 11:55
The title is in analogy to the saying "where one
sheep goes, follows another". I had to think about
when I
read
about Ecuador's Constitutional Assemblage who
approved last week articles that "recognize rights
for nature and ecosystems". At least, it
could
be a first step in the right direction. However, as
we all know, principles are often beautifully
phrased, but practices are more often quite
miserable...
Look at these figures about remaining ecosystems and their protection in the same country:
It fits very well with the recent observations by Jens Hemmen: "Most of the localities mentioned in the older literature are destroyed by clearing. There are only fields, plantages or pasture-land, even in high altitudes". This could be certainly one of the explanations why so many species have not been recollected after their initial description in this country. When I run through my recent checklist of Ecuadorian Orthalicidae, roughly 25% of the mainland species falls into that category.
The impact of ecosystem loss on vertebrates is much better known. We are only beginning to understand what this means for habitat functioning and their negative impact for humans. Snails and their value in ecosystems are much less known and this is a vast area open for further research.
Look at these figures about remaining ecosystems and their protection in the same country:
It fits very well with the recent observations by Jens Hemmen: "Most of the localities mentioned in the older literature are destroyed by clearing. There are only fields, plantages or pasture-land, even in high altitudes". This could be certainly one of the explanations why so many species have not been recollected after their initial description in this country. When I run through my recent checklist of Ecuadorian Orthalicidae, roughly 25% of the mainland species falls into that category.
The impact of ecosystem loss on vertebrates is much better known. We are only beginning to understand what this means for habitat functioning and their negative impact for humans. Snails and their value in ecosystems are much less known and this is a vast area open for further research.
Another garden slug, new to science
14-07-2008 07:55
Incidentally the morning post brought me another
piece of European malacological news. Selenochlamys
ysbryda (Trigonochlamydidae) was discovered in Wales.
It is an eyeless species that probably originates
from caves and is supposed to be introduced in plant
pots. The radula shows that it is carnivorous and the
species is reported to feed on earthworms.
Thanks Carl, for sending me the link.
Update: the paper by Rowson & Symondson describing the new species can be found in Journal of Conchology 39: 537-552.
Thanks Carl, for sending me the link.
Update: the paper by Rowson & Symondson describing the new species can be found in Journal of Conchology 39: 537-552.
Garden slug
13-07-2008 15:24
This time a change of focus out of the Neotropics.
While doing some gardening, this reddish-brown Arion ater (L., 1758) came to light. This omnivorous species can also attack living plants although it is said to feed mostly on dedritus. I found it when I removed a Berberis sp., only a single specimen.
While doing some gardening, this reddish-brown Arion ater (L., 1758) came to light. This omnivorous species can also attack living plants although it is said to feed mostly on dedritus. I found it when I removed a Berberis sp., only a single specimen.
Orthalicus as a pest
11-07-2008 12:02
Searching for literature about snails as pest
species, I came across a paper* describing Orthalicus
maracaibensis (Pfeiffer, 1856) attacking Citrus spp.
It was reported from Yumare in northern Venezuela.
The nice thing about the paper was the multitude of
pictures from live specimens :-)
Update: Carl Christensen sent me this paper of Deisler, who states that tree snails may be beneficial "because they feed on epiphytic growths." The only other record I have on Orthalicoidea as agricultural pests, is this paper by Stange. He cites that Amphibulima patula dominicanus Pilsbry, 1899 has been reported as feeding on citrus.
Reference:
Ordosgoitti, A. (1999). Caracoles plagas de cítricas en Yumare, Estado Yaracuy. Agronoía Tropical, 49, 517-525.
Update: Carl Christensen sent me this paper of Deisler, who states that tree snails may be beneficial "because they feed on epiphytic growths." The only other record I have on Orthalicoidea as agricultural pests, is this paper by Stange. He cites that Amphibulima patula dominicanus Pilsbry, 1899 has been reported as feeding on citrus.
Reference:
Ordosgoitti, A. (1999). Caracoles plagas de cítricas en Yumare, Estado Yaracuy. Agronoía Tropical, 49, 517-525.
Dead but still interesting
09-07-2008 11:38
Some months ago, Francisco Borrero found many dead
shells in a field near the airport of Catamyo, Prov.
Loja, Ecuador. While it resembles Naesiotus quitensis
(Pfeiffer, 1848) in shell shape, it may actually be a
Bostryx species, possibly B. juana (Coussin, 1887)
[to be confirmed after inspection of the material].
The habitat were here found them is also interesting, although doesn't look spectacular albeit scenic. Interesting, however, is the fact that it is part of a larger system of small interandean valleys, with a dry climate but occasionally flooded after rains.
Such localities often harbour endemic species and are dry pockets in an otherwise more humid environment. I remember having found similar conditions in Colombia, where Naesiotus gerenorum (Breure, 1977) and N. jullensorum (Breure, 1977) were collected in Dept. Boyacá, near Soatá.
The habitat were here found them is also interesting, although doesn't look spectacular albeit scenic. Interesting, however, is the fact that it is part of a larger system of small interandean valleys, with a dry climate but occasionally flooded after rains.
Such localities often harbour endemic species and are dry pockets in an otherwise more humid environment. I remember having found similar conditions in Colombia, where Naesiotus gerenorum (Breure, 1977) and N. jullensorum (Breure, 1977) were collected in Dept. Boyacá, near Soatá.
The tail of a snail: more on Achatina
08-07-2008 07:17
Some snails have longer tails than others, especially
if they are so slimy like Achatina fulica is. But
first a note on taxonomy before we dive further into
the Neotropical story of it's distribution.
Fontanilla et al. (2007) reported on phylogenetic work with Achatina fulica and came to the conclusion that it should taxonomically designated Lissachatina fulica. There is a second species from East Africa which belongs to this genus (Fontanilla, pers. comm.). The interesting thing is that they found that all globally dispersed populations originate from a single haplotype, originating from East Africa.
Modesto Correoso, the only person who is doing serious work on land snails in Ecuador, kindly drew my attention to the fact that in 2005 he purchased some specimens of Lissachatina fulica on a market in Esmeraldas (northwestern Ecuador) and this fact was picked up by a journalist of the newspaper El Comercio.
This was evidently the source of the reference I wrote about last week. Later, Correoso wrote a paper in a technical bulletin of a local institution. Unfortunately this has escaped the attention of the scientific community, but I like to give credits to the person who deserves them.
So we might think that the story ends here. Just an unfortunate introduction of a species that has been more or less officially reported on. Children who have fun with it as pets and some people who are earning money with it.
But like in any good detective, the next, unexpected plot is just one page away...
The article in the newspaper was mentioned on a discussion forum on aquaculture. And from there the trail leads to Venezuela. Again. Because back in 1997, Rafael Martinez found already some shells near Caracas and reported on them. Not sure what happened exactly, but his paper gives the impression that this seemed a non-established population. However, from this blog entry it may be clear that L. fulica has now reached a pest status several hundreds kilometers west of the locality reported on by Martinez. So it is evident that the species has become well established in Venezuela, but to what extent is unclear at the moment.
This is certainly not a soap series, but I'm afraid I have to say: to be continued...
Update: Barbados is another place where L. fulica has been established, according to this blog. It is said to have entered the island through the port. Barbados has spent an estimated US$ 500,000 over the past eight years in an effort to eradicate the Giant African Snail that has been infesting crops in countries across the Caribbean.
Some of the comments to this blogpost:
"We are not the first country to be infested. The GAS have been on a world tour since leaving east Africa two centuries ago. It was only a matter of time before they reached our shores. It has been found that hand collecting is the best way to do away with them however you then have to kill them. Immersion in salt water doesn’t work too well and the odor produced is not pleasant. One test found that there was an 85% survival rate after 48 hours of soaking. Burning works but stinks. Same for boiling. The surest method is to make sure that the shell is well broken. I propose that the Min of Ag distribute appropriately coloured and stenciled plastic bags that homeowners can put out with the garbage. At the dump they can easily be sorted out, run through a crusher and buried in a deep trench.
When to collect them. Don’t waste your time if it hasn’t rained for 2 or 3 days but if it rains off and on and is overcast much of the day the snails will be out foraging. During the rainy season you can usually go out at 5 p.m. and collect several hundred before 6:30 p.m. If you go out at 5 a.m. you will likely be able to collect 6 to 700 per hour through to 8 a.m. when you will no longer find enough to warrant the effort. I roam over 2 acres of land every morning and some evenings. My best day I collected 3,000. For the month of November my total was 42,000. Since then the dry season has yielded an average of 15,000 per month."
According to Pestalert, this snail is besides Guadeloupe, Martinique and Barbados, also known from St. Lucia.
References:
Correoso, M. (2006). Estrategia preliminar para evaluar y erradicar Achatina fulica (Gastropoda: Achatineaceae) en Ecuador. Boletim Técnico IASA, Serie Zoológica, 2: 45-52.
Fontanilla, I. K., Hudelot, C., Naggs, F. & Wade, C.M. (2007). Achatina fulica: its molecular phylogeny and genetic variation in global populations. http://www.malacsoc.org.uk/The_Malacologist/BULL48/forum48.htm. Re-published: Abstracts World Congress of Malacology, Antwerp, 15-20 July 2007: 63.
Martinez, R. & Martinez, E. (1997). Nota acerca de la Achatina (Lissachatina) fulica (Bowdich, 1822). Peligroso caracol africano (Pulmonata-Achatinidae) introducido en Venezuela. Acta Biologica Venezuelica, 17: 37-40.
Fontanilla et al. (2007) reported on phylogenetic work with Achatina fulica and came to the conclusion that it should taxonomically designated Lissachatina fulica. There is a second species from East Africa which belongs to this genus (Fontanilla, pers. comm.). The interesting thing is that they found that all globally dispersed populations originate from a single haplotype, originating from East Africa.
Modesto Correoso, the only person who is doing serious work on land snails in Ecuador, kindly drew my attention to the fact that in 2005 he purchased some specimens of Lissachatina fulica on a market in Esmeraldas (northwestern Ecuador) and this fact was picked up by a journalist of the newspaper El Comercio.
This was evidently the source of the reference I wrote about last week. Later, Correoso wrote a paper in a technical bulletin of a local institution. Unfortunately this has escaped the attention of the scientific community, but I like to give credits to the person who deserves them.
So we might think that the story ends here. Just an unfortunate introduction of a species that has been more or less officially reported on. Children who have fun with it as pets and some people who are earning money with it.
But like in any good detective, the next, unexpected plot is just one page away...
The article in the newspaper was mentioned on a discussion forum on aquaculture. And from there the trail leads to Venezuela. Again. Because back in 1997, Rafael Martinez found already some shells near Caracas and reported on them. Not sure what happened exactly, but his paper gives the impression that this seemed a non-established population. However, from this blog entry it may be clear that L. fulica has now reached a pest status several hundreds kilometers west of the locality reported on by Martinez. So it is evident that the species has become well established in Venezuela, but to what extent is unclear at the moment.
This is certainly not a soap series, but I'm afraid I have to say: to be continued...
Update: Barbados is another place where L. fulica has been established, according to this blog. It is said to have entered the island through the port. Barbados has spent an estimated US$ 500,000 over the past eight years in an effort to eradicate the Giant African Snail that has been infesting crops in countries across the Caribbean.
Some of the comments to this blogpost:
"We are not the first country to be infested. The GAS have been on a world tour since leaving east Africa two centuries ago. It was only a matter of time before they reached our shores. It has been found that hand collecting is the best way to do away with them however you then have to kill them. Immersion in salt water doesn’t work too well and the odor produced is not pleasant. One test found that there was an 85% survival rate after 48 hours of soaking. Burning works but stinks. Same for boiling. The surest method is to make sure that the shell is well broken. I propose that the Min of Ag distribute appropriately coloured and stenciled plastic bags that homeowners can put out with the garbage. At the dump they can easily be sorted out, run through a crusher and buried in a deep trench.
When to collect them. Don’t waste your time if it hasn’t rained for 2 or 3 days but if it rains off and on and is overcast much of the day the snails will be out foraging. During the rainy season you can usually go out at 5 p.m. and collect several hundred before 6:30 p.m. If you go out at 5 a.m. you will likely be able to collect 6 to 700 per hour through to 8 a.m. when you will no longer find enough to warrant the effort. I roam over 2 acres of land every morning and some evenings. My best day I collected 3,000. For the month of November my total was 42,000. Since then the dry season has yielded an average of 15,000 per month."
According to Pestalert, this snail is besides Guadeloupe, Martinique and Barbados, also known from St. Lucia.
References:
Correoso, M. (2006). Estrategia preliminar para evaluar y erradicar Achatina fulica (Gastropoda: Achatineaceae) en Ecuador. Boletim Técnico IASA, Serie Zoológica, 2: 45-52.
Fontanilla, I. K., Hudelot, C., Naggs, F. & Wade, C.M. (2007). Achatina fulica: its molecular phylogeny and genetic variation in global populations. http://www.malacsoc.org.uk/The_Malacologist/BULL48/forum48.htm. Re-published: Abstracts World Congress of Malacology, Antwerp, 15-20 July 2007: 63.
Martinez, R. & Martinez, E. (1997). Nota acerca de la Achatina (Lissachatina) fulica (Bowdich, 1822). Peligroso caracol africano (Pulmonata-Achatinidae) introducido en Venezuela. Acta Biologica Venezuelica, 17: 37-40.
A poor man's science?
07-07-2008 16:26
My newspaper had this weekend a small article on
taxonomy in their science section. This time, not one
of the thrilling new findings that make it to the
headlines from time to time. But about one of the
essences of taxonomic work: identifying new species
and giving them a proper name.
While it is not uncommon for any taxonomist to use the names of friends and esteemed colleagues, this is quite something else. New names are for sale! Some research institutions offer them, starting at 5000 US$. Sell by auction.
If I ever thought that taxonomy is a poor man's science, this is the sad proof!
While it is not uncommon for any taxonomist to use the names of friends and esteemed colleagues, this is quite something else. New names are for sale! Some research institutions offer them, starting at 5000 US$. Sell by auction.
If I ever thought that taxonomy is a poor man's science, this is the sad proof!
Achatina in Ecuador
02-07-2008 09:08
Recently I wrote about an observation of some
pet
snails
near Mindo, which turn out to be Achatina fulica
(Bowdich, 1822). This is the first record for this
species in Ecuador. Very unfortunately, I should add,
as this pet species is a dangerous pest!
It looks very much that economic profit (or better: stupid shortsightedness) has lured somebody to set up a snail farm in Ecuador. My guess is that they know very well what they are doing, since on the CORPEI site they call it concealed "Chinese Escargot". But we know better than that...
A recent paper has described the rapid spread of this species in Brazil. Let's just hope that it will be possible to eradicate it in Ecuador, before it becomes a major threat to agriculture, health and biodiversity. Just today I got confirmation from an independent source that Achatina has been found this year in a ship which came from Guayaquil.
Update: Thanks to Carl Christensen, who found the following text in a newsletter of a tourist information organisation, we now know that already in 2005 Achatina must have been established in the country:
False promises and African snails
The offer to receive a spotlessly clean skin thanks to snail slime could destroy the ecosystem of a whole country. On the basis of publications about the thaumaturgy of the cream made of the secretion, there has been a development of a parallel market along the streets of the coast that does not apply to any regulations.
The main problem is that for the fabrication of the salve animals of the breed Giant African Snail (Achatina fulica) are used. The name of the giant derives from its size that can extend in its natural tropical surroundings in West Africa more than 11.8 inches. The mollusks which can be bought for one dollar a piece are sold in Esmeraldas for example as domestic species [emphasis added]. The situation is been aggravated by the fact that the Giant African Snail looks very similar to the Ecuadorian Amazonian breed (Strophocheilus popelairianius) which is close to extinction!
The ministry of the environment is concerned: the gluttony of the intruder, its high reproduction rate and its existence as carrier of a disease makes it to a special blatant danger. The snails nourish on agricultural products and thus form a risk for banana plantations, vegetable fields and fruit trees. The immediate extermination of the pest is indispensable! In some countries such as the USA, Australia, Canada, China and Israel the breed and import of the snails is illegal – whereas its flesh is much liked by the Italians and Spaniards.
It looks very much that economic profit (or better: stupid shortsightedness) has lured somebody to set up a snail farm in Ecuador. My guess is that they know very well what they are doing, since on the CORPEI site they call it concealed "Chinese Escargot". But we know better than that...
A recent paper has described the rapid spread of this species in Brazil. Let's just hope that it will be possible to eradicate it in Ecuador, before it becomes a major threat to agriculture, health and biodiversity. Just today I got confirmation from an independent source that Achatina has been found this year in a ship which came from Guayaquil.
Update: Thanks to Carl Christensen, who found the following text in a newsletter of a tourist information organisation, we now know that already in 2005 Achatina must have been established in the country:
False promises and African snails
The offer to receive a spotlessly clean skin thanks to snail slime could destroy the ecosystem of a whole country. On the basis of publications about the thaumaturgy of the cream made of the secretion, there has been a development of a parallel market along the streets of the coast that does not apply to any regulations.
The main problem is that for the fabrication of the salve animals of the breed Giant African Snail (Achatina fulica) are used. The name of the giant derives from its size that can extend in its natural tropical surroundings in West Africa more than 11.8 inches. The mollusks which can be bought for one dollar a piece are sold in Esmeraldas for example as domestic species [emphasis added]. The situation is been aggravated by the fact that the Giant African Snail looks very similar to the Ecuadorian Amazonian breed (Strophocheilus popelairianius) which is close to extinction!
The ministry of the environment is concerned: the gluttony of the intruder, its high reproduction rate and its existence as carrier of a disease makes it to a special blatant danger. The snails nourish on agricultural products and thus form a risk for banana plantations, vegetable fields and fruit trees. The immediate extermination of the pest is indispensable! In some countries such as the USA, Australia, Canada, China and Israel the breed and import of the snails is illegal – whereas its flesh is much liked by the Italians and Spaniards.