apr 2008
Photo of the day (9): Bostryx
30-04-2008 10:57
To finish my series on Peruvian Bostryx, today a
picture of another species found in the Rio Cañete
valley. It is known under a Weyrauch manuscript-name.
Botryx granulatus
WeyrauchMS
Botryx granulatus
WeyrauchMSAnother 'living laboratory'
28-04-2008 10:17
While I have mentioned the Rio Rimac valley as a
'living laboratory'
here
and
here,
I should also mention a parellel valley somewhat
further to the south: the valley of the Rio Cañete.
This is a place where Weyrauch collected and
described various [16] new Bostryx (sub)species. I
can remember it as an interesting valley, with many
cacti and a beautiful scenery. My memory may be
flawed, though, since it was my first collecting trip
outside Lima and I was surely impressed.
As Weyrauch has shown*, several species are highly variable and show decollate whorls (e.g. Bostryx imeldae, B. zilchi both from Laraos), a phenomenon also observed in the valley of Rio Rimac.
But even when snails go less 'wild' it may become interesting, as shown by this series of shells, from two localities in the Rio Cañete valley at 2200 resp. 3300 m altitude:
Are these four different taxa (labelled as such by Weyrauch) or merely variations within one species? To what extent plays one's stand on the continuum 'splitter' versus 'lumper' a role?
Anyway, my final verdict is that these shells all belong to the same species (and a hitherto undescribed one). But indeed, it would be very interesting to be able to visit this 'living laboratory' again and investigate the biological processes behind all these shells and genes 'going wild'.
References:
Weyrauch, W.K. (1958) Neue Landschnecken und neue Synonyme aus Südamerika, 1. Archiv für Molluskenkunde 87: 91-139.
Weyrauch, W.K. (1960) Siebzehn neue Landschnecken aus Peru. Archiv für Molluskenkunde 89: 117-132.
As Weyrauch has shown*, several species are highly variable and show decollate whorls (e.g. Bostryx imeldae, B. zilchi both from Laraos), a phenomenon also observed in the valley of Rio Rimac.
But even when snails go less 'wild' it may become interesting, as shown by this series of shells, from two localities in the Rio Cañete valley at 2200 resp. 3300 m altitude:
Are these four different taxa (labelled as such by Weyrauch) or merely variations within one species? To what extent plays one's stand on the continuum 'splitter' versus 'lumper' a role?
Anyway, my final verdict is that these shells all belong to the same species (and a hitherto undescribed one). But indeed, it would be very interesting to be able to visit this 'living laboratory' again and investigate the biological processes behind all these shells and genes 'going wild'.
References:
Weyrauch, W.K. (1958) Neue Landschnecken und neue Synonyme aus Südamerika, 1. Archiv für Molluskenkunde 87: 91-139.
Weyrauch, W.K. (1960) Siebzehn neue Landschnecken aus Peru. Archiv für Molluskenkunde 89: 117-132.
Puzzles taxonomists have to solve
26-04-2008 10:29
Bostryx is the genus of South American land snails
that is really quite fascinating. There are several
hundreds of species (or at least: taxa) known and
these occur throughout the Andes with emphasis on
Peru. There is morphological variation is
astonishing, from turrited to discoidal and anything
in between.
While in 1979* I needed some 20 species to depict this variation, in the material collected by Weyrauch I found specimens from one locality covering nearly the whole range.
Imagine that the elongated shell in the right-hand upper corner gradually becomes the lower shell through a transitional series. That is not only taxonomically relevant to observe (found apart one would call these shells separate species), but raises a number of other questions as well. What is the genetical mechanism behind this phenomenon? Are there any ecological differences?
This is apparently the material to which Weyrauch referred in his 1956 paper*: "As I will illustrate in a later paper [which he never published], the variation in a population of a new subspecies of Bostryx eremothauma (Pilsbry) comprises all forms hitherto placed in the polyphyletic 'shape-types' of Peronaeus, Ataxus, Lissoacme, Platybostryx and Discobostryx [at the time that Weyrauch wrote this, these were all considered as subgenera of Bostryx; now synonyms of Bostryx sensu lato]. This great variation of shape, not observed in any other species of land shells, agress with the still greater diversification of shapes in different species of the genus Bostryx. This is evidently due to the young age of this genus". As I recently pointed out here, it is very well possible that in some places the speciation processes is in full progress. The Rio Rimac valley, where also the specimens were collected shown above, is definitely a place of special interest to any malacologist.
Incidentally, I came across a recent paper of Cook* mentioning that high-spired shells tend to be active on vertical surfaces, while low-spired species use horizontal substrates. Differences in shape are associated with microhabitats, which would suggest that the specimens shown here have different niches within the same locality. Unfortunately the museum labels don't tell us anything about it. For me it is one of the reasons why field work is a necessary complement to museum work and why it should be well documented.
References:
Breure, A.S.H. (1979) Systematics, phylogeny and zoogeography of Bulimulinae (Mollusca). Zoologische Verhandelingen 168: 1-215 [The variation in Bostryx is shown on p. 47].
Cook, L. M. (2008). Species richness in Madeiran land snails, and its causes. Journal of Biogeography 35, 647-653.
Weyrauch, W.K. (1956) The genus Naesiotus, with descriptions of new species and notes on other Peruvian Bulimulidae. Proceedings of the Academy of Natural Sciences of Philadelphia 108: 1-17.
While in 1979* I needed some 20 species to depict this variation, in the material collected by Weyrauch I found specimens from one locality covering nearly the whole range.
Imagine that the elongated shell in the right-hand upper corner gradually becomes the lower shell through a transitional series. That is not only taxonomically relevant to observe (found apart one would call these shells separate species), but raises a number of other questions as well. What is the genetical mechanism behind this phenomenon? Are there any ecological differences?
This is apparently the material to which Weyrauch referred in his 1956 paper*: "As I will illustrate in a later paper [which he never published], the variation in a population of a new subspecies of Bostryx eremothauma (Pilsbry) comprises all forms hitherto placed in the polyphyletic 'shape-types' of Peronaeus, Ataxus, Lissoacme, Platybostryx and Discobostryx [at the time that Weyrauch wrote this, these were all considered as subgenera of Bostryx; now synonyms of Bostryx sensu lato]. This great variation of shape, not observed in any other species of land shells, agress with the still greater diversification of shapes in different species of the genus Bostryx. This is evidently due to the young age of this genus". As I recently pointed out here, it is very well possible that in some places the speciation processes is in full progress. The Rio Rimac valley, where also the specimens were collected shown above, is definitely a place of special interest to any malacologist.
Incidentally, I came across a recent paper of Cook* mentioning that high-spired shells tend to be active on vertical surfaces, while low-spired species use horizontal substrates. Differences in shape are associated with microhabitats, which would suggest that the specimens shown here have different niches within the same locality. Unfortunately the museum labels don't tell us anything about it. For me it is one of the reasons why field work is a necessary complement to museum work and why it should be well documented.
References:
Breure, A.S.H. (1979) Systematics, phylogeny and zoogeography of Bulimulinae (Mollusca). Zoologische Verhandelingen 168: 1-215 [The variation in Bostryx is shown on p. 47].
Cook, L. M. (2008). Species richness in Madeiran land snails, and its causes. Journal of Biogeography 35, 647-653.
Weyrauch, W.K. (1956) The genus Naesiotus, with descriptions of new species and notes on other Peruvian Bulimulidae. Proceedings of the Academy of Natural Sciences of Philadelphia 108: 1-17.
Productive silence
24-04-2008 09:58
What for you seems to be silence on my behalf (this
blog actually being published on 2 May), was actually
a holiday in the Belgian Ardennes where I did not
have access to the internet. Not that it would have
been impossible, but I just happen to have a mobile
phone account without internet. So I'm having some
quiet days here with part of my family and meanwhile
I'm working hard to get the manuscript of Weyrauch's
Bostryx MS-names finished as the deadline is rapidly
approaching.
I also took some material with me from Venezuela and loaded my laptop with some additional literature. No doubt that this week will be both enjoyable and productive somehow.
I also took some material with me from Venezuela and loaded my laptop with some additional literature. No doubt that this week will be both enjoyable and productive somehow.
Phylogeographer
20-04-2008 21:08
Another piece of software, that looks potentially
useful.
Phylogeographer
is designed to test phylogeographic hypotheses,
allowing the hypotheses to be converted into distance
matrices. These can be used to calculate correlations
between various hypotheses and genetic distance
matrices. This way dispersal routes can be explored
with a graphical interface.
The (condensed) information on the homepage suggests that this piece of software is relatively easy to operate, once you stick to some basic requirements (formats). One of the big advantages is that it runs under Java, so platform-independent.
Later this year I hope to have enough data for a further exploration. So this topic might return.
The (condensed) information on the homepage suggests that this piece of software is relatively easy to operate, once you stick to some basic requirements (formats). One of the big advantages is that it runs under Java, so platform-independent.
Later this year I hope to have enough data for a further exploration. So this topic might return.
Treebase
20-04-2008 20:10
Google Earth (GE) has been mentioned in this blog
several times or at least I have shown results using
this nifty piece of software.
Today I stumbled upon the site of the CIPRES project, one of its aims is the development of TreeBASE II, re-engineered to allow for the use of GE. They provide a prototype tree viewer which included some sample trees. One of them is based on the article of Gittenberger et al. (2004) with land snails from Europe. I know it is a small diversion from the theme of this blog, but it's nice to see the work of a friend and colleague being used in an innovative way.
The site also allows for uploads of trees, I suppose they will potentially be included as examples in a next version. Nice piece of work...
Reference:
Gittenberger, E, W. H. Piel and D. Groenenberg. 2004. The Pleistocene glaciations and the evolutionary history of the polytypic snail species Arianta arbustorum (Gastropoda, Helicidae). Molecular Phylogenetics and Evolution, 30(1): 64-67
Today I stumbled upon the site of the CIPRES project, one of its aims is the development of TreeBASE II, re-engineered to allow for the use of GE. They provide a prototype tree viewer which included some sample trees. One of them is based on the article of Gittenberger et al. (2004) with land snails from Europe. I know it is a small diversion from the theme of this blog, but it's nice to see the work of a friend and colleague being used in an innovative way.
The site also allows for uploads of trees, I suppose they will potentially be included as examples in a next version. Nice piece of work...
Reference:
Gittenberger, E, W. H. Piel and D. Groenenberg. 2004. The Pleistocene glaciations and the evolutionary history of the polytypic snail species Arianta arbustorum (Gastropoda, Helicidae). Molecular Phylogenetics and Evolution, 30(1): 64-67
Online databases
17-04-2008 19:26
Undoubtedly a great help and I wished there were even
more of them, but at the same time it has to be
recognized that the content cannot always be trusted.
It is the same old story: GIGO, garbage in, garbage
out.
The most logical start would be GBIF. I have seen some quite good results when I consulted their Australian data on Bulimulidae, but when I searched for data on South American species the results were poor. So far, databases from individual museums are for me a better choice. Here is a list of the databases that I have consulted quite frequently during my current research.
EU. There are several databases, of which the Senckenberg, Berlin and Brussels museums are the most promising. Yet they all ask me to come over to study their collection and and to look for what I need. To travel or to loan, that's an other interesting topic...
USA. For me the most informative database is those of the Florida Museum (chapeau Fred and John!). Also very useful are the Field Museum and Philadelphia museum databases. Furthermore I have consulted the Smithsonian and Harvard museum databases. It is always a good start, but don't forget to contact the curator to get the full details
Brazil. The list of institutions that participate in the speciesLink project is impressive. However, there are currently only three malacological collections accessible (although I regularly encountered server errors): INPA-Mollusca (Manáus, Amazonas), UFES-Malacologia (Vitória, Espírito Santo) and ZUEC-GAS (Unversidade de UNICAMP, Campinas, São Paulo). After several trials I ended up with a partial list of results only. UFES was the only database to respond, which may be due to the distributed set up of the project. Still a start that can only improve over time.
Finally, I like to mention here a recent paper by Neale et al.* on some principles for usability. They highlight the need for end-user involvement in the development of online databases. I cannot stress the importance of this point enough!
Reference:
Neale, S. H., M.R. Pullan & M.F. Watson. (2007). Online biodiversity resources - principles for usability. Biodiversity Informatics, 4, 27-36.
The most logical start would be GBIF. I have seen some quite good results when I consulted their Australian data on Bulimulidae, but when I searched for data on South American species the results were poor. So far, databases from individual museums are for me a better choice. Here is a list of the databases that I have consulted quite frequently during my current research.
EU. There are several databases, of which the Senckenberg, Berlin and Brussels museums are the most promising. Yet they all ask me to come over to study their collection and and to look for what I need. To travel or to loan, that's an other interesting topic...
USA. For me the most informative database is those of the Florida Museum (chapeau Fred and John!). Also very useful are the Field Museum and Philadelphia museum databases. Furthermore I have consulted the Smithsonian and Harvard museum databases. It is always a good start, but don't forget to contact the curator to get the full details
Brazil. The list of institutions that participate in the speciesLink project is impressive. However, there are currently only three malacological collections accessible (although I regularly encountered server errors): INPA-Mollusca (Manáus, Amazonas), UFES-Malacologia (Vitória, Espírito Santo) and ZUEC-GAS (Unversidade de UNICAMP, Campinas, São Paulo). After several trials I ended up with a partial list of results only. UFES was the only database to respond, which may be due to the distributed set up of the project. Still a start that can only improve over time.
Finally, I like to mention here a recent paper by Neale et al.* on some principles for usability. They highlight the need for end-user involvement in the development of online databases. I cannot stress the importance of this point enough!
Reference:
Neale, S. H., M.R. Pullan & M.F. Watson. (2007). Online biodiversity resources - principles for usability. Biodiversity Informatics, 4, 27-36.
Specialization and speciation (cont'd)
16-04-2008 19:13
The other conclusion of Patten that make me think, is
that "lowered genetic variance associated with
specialization may also lead to extended periods
during which generalists beget specialists and
specialists beget more specialists but during which
few generalists evolve. (...) Accordingly, over time
populations will edge steadily towards the specialist
pole of the generalist-specialist continuum".
The question is here, in malacological terms, what makes a land snail a specialist and how do you know? Is that by populations adapting to a narrow ecological niche? Than one could infer their stand on the generalist-specialist continuum from their distribution pattern. A range-restricted species would be more 'specialist' than a wide-spread species. Or could one say that certain 'life styles' (e.g. arboreal versus under stones or feeding on rocks) are to be considered more specialized? What is then, to speak in cladistic terms, to be considered plesiomorph and what apomorph? And what is the role of convergence*?
Patten also argues that "there should be a net accumulation of specialists over time...to a point. Because of their reduced ability to evolve, specialists are more likely than generalists to pay the price when, say, climate or habitat changes rapidly." This is an interesting hypothesis, especially when fossils are good represented in a group and they could tell us something about the position on the generalist-specialist continuum. I'm afraid that land snail fossils are poorly represented (at least in the Neotropics) and not very informative (often only the shell shape). So, at least for the moment, there are more questions than crisp and clear insights.
Reference:
Breure, A. S. H. & E. Gittenberger (1982). The rock-scraping radula, a striking case of convergence (Mollusca). Netherlands Journal of Zoology, 32, 307-312
The question is here, in malacological terms, what makes a land snail a specialist and how do you know? Is that by populations adapting to a narrow ecological niche? Than one could infer their stand on the generalist-specialist continuum from their distribution pattern. A range-restricted species would be more 'specialist' than a wide-spread species. Or could one say that certain 'life styles' (e.g. arboreal versus under stones or feeding on rocks) are to be considered more specialized? What is then, to speak in cladistic terms, to be considered plesiomorph and what apomorph? And what is the role of convergence*?
Patten also argues that "there should be a net accumulation of specialists over time...to a point. Because of their reduced ability to evolve, specialists are more likely than generalists to pay the price when, say, climate or habitat changes rapidly." This is an interesting hypothesis, especially when fossils are good represented in a group and they could tell us something about the position on the generalist-specialist continuum. I'm afraid that land snail fossils are poorly represented (at least in the Neotropics) and not very informative (often only the shell shape). So, at least for the moment, there are more questions than crisp and clear insights.
Reference:
Breure, A. S. H. & E. Gittenberger (1982). The rock-scraping radula, a striking case of convergence (Mollusca). Netherlands Journal of Zoology, 32, 307-312
Specialization and speciation
15-04-2008 16:41
The title refers to an interesting recently
commentary in the Journal of Biogeography*, where
Michael Patten argues that speciation and
specialization are the same phenomenon. I'm not going
to repeat his arguments here, but some of his
conclusions are mind-provocative.
The first is that a simple geographic barrier becomes inadequate to 'explain' divergence between populations. If subtle differences in climate lead to subtle difference in vegetation, which in turn leads to different behaviour. In most cases one have to think in geological timescales to imagine how these subtle differences lead to larger differences and effective speciation comes into play.
I always wonder how these general theories work out in malacology. Just an example that puzzles me, possibly speciation still at work.
Imagine you see the shells above. The only thing you know is that they all occur in the same region, more or less at the same altitude, but at two sides of a river. I have plotted the (approximate) localities (taken from labels and collected some 40 years ago) on this map:
Now the question is, what would you call it? One species? Four subspecies? Two subspecies? I'm inclined to say the latter, but this case clearly needs further investigation. It would be nice to study these populations genetically to see to what extent the morphological differences can be explained. The only problem is: these animals occur high up in the Andes, Río Rimac valley, 3300-3400m. Any volunteers for collecting?
Reference:
Patten, M. A. (2008). The intersection of specialization and speciation. J. Biogeogr, 35, 193-194.
The first is that a simple geographic barrier becomes inadequate to 'explain' divergence between populations. If subtle differences in climate lead to subtle difference in vegetation, which in turn leads to different behaviour. In most cases one have to think in geological timescales to imagine how these subtle differences lead to larger differences and effective speciation comes into play.
I always wonder how these general theories work out in malacology. Just an example that puzzles me, possibly speciation still at work.
Imagine you see the shells above. The only thing you know is that they all occur in the same region, more or less at the same altitude, but at two sides of a river. I have plotted the (approximate) localities (taken from labels and collected some 40 years ago) on this map:
Now the question is, what would you call it? One species? Four subspecies? Two subspecies? I'm inclined to say the latter, but this case clearly needs further investigation. It would be nice to study these populations genetically to see to what extent the morphological differences can be explained. The only problem is: these animals occur high up in the Andes, Río Rimac valley, 3300-3400m. Any volunteers for collecting?
Reference:
Patten, M. A. (2008). The intersection of specialization and speciation. J. Biogeogr, 35, 193-194.
Photo of the day (8): Dryptus
13-04-2008 15:45
Today I show a recently received picture of Dryptus
marmoratus (Dunker, 1844) from Venezuela, Estado
Aragua, National Park 'Henri Pittier', made in
January 2008.
Photo by Jozef Steffek
Photo by Jozef Steffek
Photo of the day (7): Drymaeus
12-04-2008 15:04
This photo was made in Peru, Dept. Huánuco, near
Tingo Maria, Cuevas de las Pavas. It shows Drymaeus
(D.) serratus (Pfeiffer, 1855). Thanks, Valentín.
Photo by Valentín Mogollón
Photo by Valentín Mogollón
Photo of the day (6): Drymaeus
11-04-2008 14:28
The following photograph was received for ID. It is
from Fuik Bay on Curacao and depicts Drymaeus
(Mesembrinus) multilineatus (Say, 1825).
Photo by Marcus Coltro
Photo by Marcus Coltro
Photo of the day (5): semi-slug
08-04-2008 10:12
Today I'm posting two pictures of a hitherto
unidentified semi-slug. The animal was encountered by
Clayton Kern during a hiking trip up in the mountains
on Dominica.
Any suggestions on the ID are welcome.
Thanks Clayton for the pics.
Any suggestions on the ID are welcome.
Thanks Clayton for the pics.
Gondwana: the debate continues
06-04-2008 21:20
Much has been said already (and undoubtedly more will
still be said) about the biogeography of the southern
hemisphere. In a recent review, Paul Upchurch
summarizes hypotheses about Gondwanan biogeography
into four models [here a broad summary of a summary]:
a) A 'Samafrica model' where Gondwana was divided into South America and Africa on one hand and East Gondwana (Antarctica, India, Madagascar and Australia) on the other hand.
b) The 'Africa-first' model' assumes that Africa was separated in an early stage, while South America remained longer in contact with East Gondwana until they finally broke up.
c) The 'Pan-Gondwana model' suggesting that all areas remained connected and then separated almost simultaneously.
d) 'Trans-oceanic dispersal model' following investigations of divergence times for species living on different continents and comparing them with the ages of the oceanic barriers between them.
From a theoretical point of view two phenomena have largely been ignored in biogeographical analyses: distributional noise (created by sampling errors) and the effect of geodispersal producing multiple signals. Geodispersal is the expansion of the ranges of species in response to the removal of a geographical barrier (e.g. erosion of a mountain range). Recent insights are that vicariance and geodispersal are alternating by the creation (upheaval) and destruction (erosion) of geographical barriers. The result is a network of interactions between biotas, rather than a simple branching pattern produced by vicariance alone (also called 'reticulate model'). This pattern may be group specific, depending on their specific reactions to physical events and their ecological requirements. Thus multiple biogeographical patterns may occur and recently some patterns-spotting techniques have been developed to untangle reticulate histories.
Upchurch continues by giving some implications for palaeobiogeography and molecular biology. E.g. he criticizes the lack of uncertainty in calibration of ages of fossil taxa (divergence times should be given with a confidence interval) and the calibration of molecular clocks using the age of geographical barriers. Different groups produce different patterns because of genuine biological processes (e.g. their difference in dispersal mechanism), but it is likely that partly the debate is flawed by ambiguities caused by distributional noise and multiple signals. His conclusion is that Gondwanan biogeographical history is proving to be even more complex than previously realized. He strongly advocates the use of pattern-spotting methods to distinguish between genuine patterns and artefacts produced by sampling and other errors.
I think that Upchurch has a point in arguing that the biogeographical history of Gondwana is even more complex than realized so far. Ranges in time expressing uncertainty and different scenarios could be more explicit, especially when dealing with older geological times. Possibly too often nuances are lost (or condensed) in the editing process, given the maximum number of pages a paper is allowed in many journals. And I wonder if the dispersal mechanism of the particular group under consideration is always given sufficient weight. It may be a dilemma to balance between generalizations and the specifics of the group.
There are several points in this useful review that are worthwhile to consider when we look into the relationships of the Orthalicidae (sensu lato). I will undoubtedly come back to this issue later.
Reference:
Upchurch, P. (2008). Gondwanan break-up: legacies of a lost world? Trends in Ecology & Evolution, 23, 229-236.
a) A 'Samafrica model' where Gondwana was divided into South America and Africa on one hand and East Gondwana (Antarctica, India, Madagascar and Australia) on the other hand.
b) The 'Africa-first' model' assumes that Africa was separated in an early stage, while South America remained longer in contact with East Gondwana until they finally broke up.
c) The 'Pan-Gondwana model' suggesting that all areas remained connected and then separated almost simultaneously.
d) 'Trans-oceanic dispersal model' following investigations of divergence times for species living on different continents and comparing them with the ages of the oceanic barriers between them.
From a theoretical point of view two phenomena have largely been ignored in biogeographical analyses: distributional noise (created by sampling errors) and the effect of geodispersal producing multiple signals. Geodispersal is the expansion of the ranges of species in response to the removal of a geographical barrier (e.g. erosion of a mountain range). Recent insights are that vicariance and geodispersal are alternating by the creation (upheaval) and destruction (erosion) of geographical barriers. The result is a network of interactions between biotas, rather than a simple branching pattern produced by vicariance alone (also called 'reticulate model'). This pattern may be group specific, depending on their specific reactions to physical events and their ecological requirements. Thus multiple biogeographical patterns may occur and recently some patterns-spotting techniques have been developed to untangle reticulate histories.
Upchurch continues by giving some implications for palaeobiogeography and molecular biology. E.g. he criticizes the lack of uncertainty in calibration of ages of fossil taxa (divergence times should be given with a confidence interval) and the calibration of molecular clocks using the age of geographical barriers. Different groups produce different patterns because of genuine biological processes (e.g. their difference in dispersal mechanism), but it is likely that partly the debate is flawed by ambiguities caused by distributional noise and multiple signals. His conclusion is that Gondwanan biogeographical history is proving to be even more complex than previously realized. He strongly advocates the use of pattern-spotting methods to distinguish between genuine patterns and artefacts produced by sampling and other errors.
I think that Upchurch has a point in arguing that the biogeographical history of Gondwana is even more complex than realized so far. Ranges in time expressing uncertainty and different scenarios could be more explicit, especially when dealing with older geological times. Possibly too often nuances are lost (or condensed) in the editing process, given the maximum number of pages a paper is allowed in many journals. And I wonder if the dispersal mechanism of the particular group under consideration is always given sufficient weight. It may be a dilemma to balance between generalizations and the specifics of the group.
There are several points in this useful review that are worthwhile to consider when we look into the relationships of the Orthalicidae (sensu lato). I will undoubtedly come back to this issue later.
Reference:
Upchurch, P. (2008). Gondwanan break-up: legacies of a lost world? Trends in Ecology & Evolution, 23, 229-236.
Accepted!
03-04-2008 15:23
Today my paper on Ecuador was accepted :-))
Although it has taken a while (submitted 19 November 2007, revised version 19 February), it was a very instructive experience. After all, it is more than 20 years ago that my last scientific paper was published. One thing is for sure, the editing process demands now a lot more of authors than it used to be...
You can find more details on the paper under 'New Granada'. Some figures that partially will go with it are below, illustrating the localities and the main results.
Although it has taken a while (submitted 19 November 2007, revised version 19 February), it was a very instructive experience. After all, it is more than 20 years ago that my last scientific paper was published. One thing is for sure, the editing process demands now a lot more of authors than it used to be...
You can find more details on the paper under 'New Granada'. Some figures that partially will go with it are below, illustrating the localities and the main results.
Photo of the day (4): Stenostylus
02-04-2008 21:02
Later this year you will see this picture again in an
upcoming paper on enigmatic species. It was taken by
Antoine M. Cleef in Colombia, Páramo de Almorzadero,
4200 m.
Stenostylus nigrolimbatus (Pfeiffer, 1854)
Stenostylus nigrolimbatus (Pfeiffer, 1854)
More on old maps
01-04-2008 08:13
While I was looking for old maps indicating the
province of Orinoco in Venezuela, I came across some
other maps which quite interesting show the political
changes in South America. Since you never know where
these maps will end up and for how long they will be
displayed on the internet I copy them here as future
reference for researchers.
South America. 1841 (published 1846). Authors: T.G. Bradford & S.G. Goodrich. Boston. (Source: antique-atlas)
Carta de la Republica de Colombia. 1840. Author: A. Codazzi (Source: David Rumsey).
Carta del Departamento del Orinoco o de Maturin. 1827. Author: J.M. Restrepo (Source: David Rumsey).
Carta del Canton de Angostura de la Provincia de Guayana. 1840. Authour: A. Codazzi (Source: David Rumsey).
Mapa de los tres Departamentos Venezuela, Cundinamarca y Ecuador que formaron la Republica de Colombia, para servir a la historia de las campanas de la guerra de independencia en los años de 1821, 1822 y 1823. 1840. Author: A. Codazzi (Source: David Rumsey).
Finally one more map on Venezuela, with two versions, one from the early 19th c. and one from the mid-1800's. The latter is the period that most shell collections were made, so I have zoomed in on some details.
Mapa politico de Venezuela antes de la Revolución de 1810. Mapa politico de Venezuela en 1840. 1840. Author: A. Codazzi (Source: David Rumsey).
South America. 1841 (published 1846). Authors: T.G. Bradford & S.G. Goodrich. Boston. (Source: antique-atlas)
Carta de la Republica de Colombia. 1840. Author: A. Codazzi (Source: David Rumsey).
Carta del Departamento del Orinoco o de Maturin. 1827. Author: J.M. Restrepo (Source: David Rumsey).
Carta del Canton de Angostura de la Provincia de Guayana. 1840. Authour: A. Codazzi (Source: David Rumsey).
Mapa de los tres Departamentos Venezuela, Cundinamarca y Ecuador que formaron la Republica de Colombia, para servir a la historia de las campanas de la guerra de independencia en los años de 1821, 1822 y 1823. 1840. Author: A. Codazzi (Source: David Rumsey).
Finally one more map on Venezuela, with two versions, one from the early 19th c. and one from the mid-1800's. The latter is the period that most shell collections were made, so I have zoomed in on some details.
Mapa politico de Venezuela antes de la Revolución de 1810. Mapa politico de Venezuela en 1840. 1840. Author: A. Codazzi (Source: David Rumsey).