feb. 2008
EOL: an ecosystem of websites
29-02-2008 21:40
Hot from the press: the Encyclopedia of Life. A new
portal pretending to have (in the end) a webpage for
each species described. It was publicized in my
newspaper on their science page.
NRC-20080228-01011009
Let's explore...The site is not very responsive (which might be due to the overwhelming number of visits after the publication, possibly a good sign) and contains not much information yet (you have to start with something). Looking at the Gastropoda, only quite number of familiar names turn up: Helix pomatia, Cepaea nemoralis and Arion subfuscus. All common European snails. The pictures are taken from a Czech biological encyclopedia (online), text and graphic show the place in a tree of life (interactive) and the source gives the origin of the classification.
My verdict: surely an endeavour that needs support, but also one that has a long, long way to go... If anyone is interested, I volunteer for the Orthalicidae :-)
NRC-20080228-01011009
Let's explore...The site is not very responsive (which might be due to the overwhelming number of visits after the publication, possibly a good sign) and contains not much information yet (you have to start with something). Looking at the Gastropoda, only quite number of familiar names turn up: Helix pomatia, Cepaea nemoralis and Arion subfuscus. All common European snails. The pictures are taken from a Czech biological encyclopedia (online), text and graphic show the place in a tree of life (interactive) and the source gives the origin of the classification.
My verdict: surely an endeavour that needs support, but also one that has a long, long way to go... If anyone is interested, I volunteer for the Orthalicidae :-)
Hidalgo and the Viaje al Pacifico
28-02-2008 21:07
For one of my papers in preparation I was looking to
solve the publication dates of Hidalgo's contribution
to the results of the 'Viajes al Pacifico'. This
well-known Spanish expedition into the Neotropics is
now extensively documented and accessible through the
internet. It's context is described by López-Ocón and
Badia (2003):
This article describes from a constructivist perspective a Natural History expedition put together by the Spanish government and navy to visit territories in the Pacific in the 1860s. Right from the start the expedition ran into problems and barely made it back. However, it managed to compile an admiringly large assortment of specimens: extensive collections of shells, mammals, skulls, and photographs. The expedition was rooted in colonialism. Patrons and organizers of the expedition sought to recreate in Spain discourses and practices then dominant in France, particularly the colonial agenda of the Société Impériale Zoologique d'Acclimatation. The collection assembled by the Comisión Científica del Pacífico had a life of its own. Years after the expedition folded, the collection kept on circulating and inspiring local and foreign scientists to identify new species and draw lessons from anthropology to history. The study of this collection was always discontinuous, a fact that proves the guadianización of science in Spain. The collection has been revived after a number of serendipitous discoveries in various Spanish archives, particularly caches of old photographs. Presently, the website www.pacifico.csic.es is expected to contribute to the circulation of the inscriptions generated by this scientific expedition.
On the website I found the plates, of which I copy two here. Plates 1 and 6 seem to be missing.
References:
Hidalgo, G. (1869) [1872]. Moluscos del Viaje al Pacifico. Parte primera: Univalvos terrestres. Madrid: Miguel Ginesta.
López-Ocón, L. & S. Badía (2003). Overcoming obstacles: The triple mobilization of the Comisión Científica del Pacífico. Science in Context, 16, 505-534.
This article describes from a constructivist perspective a Natural History expedition put together by the Spanish government and navy to visit territories in the Pacific in the 1860s. Right from the start the expedition ran into problems and barely made it back. However, it managed to compile an admiringly large assortment of specimens: extensive collections of shells, mammals, skulls, and photographs. The expedition was rooted in colonialism. Patrons and organizers of the expedition sought to recreate in Spain discourses and practices then dominant in France, particularly the colonial agenda of the Société Impériale Zoologique d'Acclimatation. The collection assembled by the Comisión Científica del Pacífico had a life of its own. Years after the expedition folded, the collection kept on circulating and inspiring local and foreign scientists to identify new species and draw lessons from anthropology to history. The study of this collection was always discontinuous, a fact that proves the guadianización of science in Spain. The collection has been revived after a number of serendipitous discoveries in various Spanish archives, particularly caches of old photographs. Presently, the website www.pacifico.csic.es is expected to contribute to the circulation of the inscriptions generated by this scientific expedition.
On the website I found the plates, of which I copy two here. Plates 1 and 6 seem to be missing.
References:
Hidalgo, G. (1869) [1872]. Moluscos del Viaje al Pacifico. Parte primera: Univalvos terrestres. Madrid: Miguel Ginesta.
López-Ocón, L. & S. Badía (2003). Overcoming obstacles: The triple mobilization of the Comisión Científica del Pacífico. Science in Context, 16, 505-534.
Google Earth and map making
25-02-2008 15:22
Since I was struggling with making a map for my
Ecuador paper, I was very happy with some tips from a
colleague. The first one was about online map making.
There are several sites, of which online map creation
(OMC)
has the basic functionality. A handy feature is
that it supports Postscript-output, which makes it
easy for publication although you might need
commercial software to process it further. The
same format is supported by
Planiglobe,
although I don't like like scaling feature as it
gives me not enough flexibility.
A second tip seems even more handy: the use of GPSVisualizer to transfer (distribution) data to KML or KMZ files as an overlay in Google Earth. Unfortunately, in the end this doesn't produce maps that are suitable for publication (unless you are the happy owner of the commercial version of GE), but after much fiddling I was able to obtain a map with localities in Ecuador.
Thanks for the tips, Bas!
A second tip seems even more handy: the use of GPSVisualizer to transfer (distribution) data to KML or KMZ files as an overlay in Google Earth. Unfortunately, in the end this doesn't produce maps that are suitable for publication (unless you are the happy owner of the commercial version of GE), but after much fiddling I was able to obtain a map with localities in Ecuador.
Thanks for the tips, Bas!
The extended family
23-02-2008 10:40
This week arrived the long-expected paper by Dai
Herbert on
Prestonella.
Or rather I should say, the first paper, as a
second one dealing with the phylogeny is still on
its way.
Since the first reference to Prestonella as a member of the Bulimulidae (Herbert & Mitchell, 2004), I have been very curious to know more about its relationships to other subfamilies or genera. Still, we have to hold our breath as this paper deals primarily with the taxonomy and presents an in-depth revision of the three taxa. The only 'sneak preview' is a statement that "Prestonella [is] in a well supported, monophyletic, orthalicoid clade structured in the following manner: Amphibulimidae + (Bulimulinae + (Prestonella + (Bothriembryon + Placostylus)))".
Herbert was able to recollect two of the species near their type localities and gives useful data on their ecology as well. The genus is endemic to South Africa and its distribution is very relictual.
It's a pity that the figures in the paper are not in colour, as these snails are very pretty (for land snails :-). This photo, by courtesy of Dai, shows Prestonella bowkeri (Sowerby, 1890).
References:
Herbert, D. G. & Mitchell, A. (2004). Prestonella, the missing African element in the Gondwanan family Bulimulidae (Mollusca, Pulmonata). Paper presented at the IV Southern Connections Conference, Cape Town, 19-23.1.2004.
Herbert, D. G. (2007). Revision of the genus Prestonella (Mollusca: Gastropoda: Orthalicoidea: Bulimulidae s.l.), a distinctive component of the African land snail fauna. African Invertebrates, 48, 1-19.
Since the first reference to Prestonella as a member of the Bulimulidae (Herbert & Mitchell, 2004), I have been very curious to know more about its relationships to other subfamilies or genera. Still, we have to hold our breath as this paper deals primarily with the taxonomy and presents an in-depth revision of the three taxa. The only 'sneak preview' is a statement that "Prestonella [is] in a well supported, monophyletic, orthalicoid clade structured in the following manner: Amphibulimidae + (Bulimulinae + (Prestonella + (Bothriembryon + Placostylus)))".
Herbert was able to recollect two of the species near their type localities and gives useful data on their ecology as well. The genus is endemic to South Africa and its distribution is very relictual.
It's a pity that the figures in the paper are not in colour, as these snails are very pretty (for land snails :-). This photo, by courtesy of Dai, shows Prestonella bowkeri (Sowerby, 1890).
References:
Herbert, D. G. & Mitchell, A. (2004). Prestonella, the missing African element in the Gondwanan family Bulimulidae (Mollusca, Pulmonata). Paper presented at the IV Southern Connections Conference, Cape Town, 19-23.1.2004.
Herbert, D. G. (2007). Revision of the genus Prestonella (Mollusca: Gastropoda: Orthalicoidea: Bulimulidae s.l.), a distinctive component of the African land snail fauna. African Invertebrates, 48, 1-19.
Cross-bordering
22-02-2008 14:12
During scanning of literature I found a paper*
dealing with entomology but containing nevertheless
information that could be handy in other fields as
well. One of the references was to site that I found
already some years ago, but lost afterwards. It
contains a useful survey of
programs for interactive
identification and information
retrieval.
As usual there is a distinction between free and
commercial respectively between Windows and other
platforms (notably Java). It will be clear why my
preference will be.
The Delta program is now called Intkey, but essentially is the same and might be useful for building keys or to allow identification of species through a webinterface. Useful but cumbersome to compile, unless you make it a hebit right from the start.
Reference:
Johnson, N. F. (2007). Biodiversity informatics. Annual Review Entomology, 52, 421-438.
The Delta program is now called Intkey, but essentially is the same and might be useful for building keys or to allow identification of species through a webinterface. Useful but cumbersome to compile, unless you make it a hebit right from the start.
Reference:
Johnson, N. F. (2007). Biodiversity informatics. Annual Review Entomology, 52, 421-438.
About lizards, geckos and snails
18-02-2008 09:00
In the last number of Systematic Biology a number of
papers are devoted to species delimitation. They are
resulting from a symposium that was held in 2006 in
Stony Brooks by the Society of Systematic Biologists
and chaired by John Wiens.
Two papers are especially noteworthy, dealing with lizards (Rissler & Apodaca, 2007) and geckos (Raxworthy et al., 2007), both exploring the use of ecological niche modelling (ENM).
While delimitation of species and species concepts are theoretically debated for some time (e.g., de Queiros, 2007; Sites & Marshall, 2003, 2004; Wiens, 2004, 2007), it is interesting to see how ENM is used to shed light from a more practical point of view. In the paper of Rissler & Apocada the distribution of different 'lineages' of a lizard is analyzed, using phylogenetic methods and bioclimate data. It includes a figure with spatial representation of the several lineages, using GeoPhyloBuilder (unfortunately only working with ArcGIS; why not cross-platform and for general GIS software??). With ENM the contact zones between the different lineages are visualized and they argue that genetic and ecological data prove to be more convincing than morphological differences between lineages. They suggest that future phylogeographic and biogeographic analyses will be more explicitly concerned with spatial and geographic components of genetic variation and speciation than is currently evident. This is certainly a challenge for Neotropical malacology.
I was even more charmed by the paper of Raxworthy et al., who deal with geckos from Madagascar. They use ENM (Maxent; review here) to identify erroneous localities (which could also be the consequence of misidentifications in collections or literature) and develop a method for comparing niche models based on split and lumped taxonomic groupings. In this study they use this method for species delimitation and unveil a cryptic species. Morphological or molecular data were used to guide for partitioning localities between suspected species. Subsequently, using both the lumped and split taxonomic groupings, niche models were compared for predictive performance. They conclude that ENM is especially useful for species delimitation in groups that show high levels of local endemism or include cryptic species which show little morphological and molecular divergence.
Their phylogenetic analyses were done using ethanol 70% and formalin-fixed specimens from museum collections. I wonder if this method would work also in snails...
References:
Raxworthy, C. J., C.M. Ingram, N. Rabibisoa & R.G. Pearson. (2007). Applications of ecological niche modeling for species delimitation: a review and empirical evalutation using day geckos (Phelsuma) from Madagascar. Systematic Biology, 56, 907-923.
Rissler, L. J. & J. J. Apodaca (2007). Adding more ecology into species delimitation: ecological niche models and phylogeography help define cryptic species in the Black Salamander (Aneides flavipunctatus). Systematic Biology, 56, 924-942.
Further references:
de Queiroz, K. (2007). Species concepts and species delimitation. Systematic Biology, 56, 879-886.
Sites, J. W. & J. C. Marshall (2003). Delimiting species: a Renaissance issue in systematic biology. Trends in Ecology and Evolution, 18, 462-470.
Sites, J. W. & J. C. Marshall (2004). Operational criteria for delimiting species. Annual Review Ecology Evolution Systematics, 35, 199-227.
Wiens, J. J. (2004). Speciation and ecology revisited: phylogenetic niche conservatism and the origin of species. Evolution, 58, 193-197.
Wiens, J.J. (2007). Species delimitation: new approaches for discovering diversity. Systematic Biology, 56, 875-878.
Two papers are especially noteworthy, dealing with lizards (Rissler & Apodaca, 2007) and geckos (Raxworthy et al., 2007), both exploring the use of ecological niche modelling (ENM).
While delimitation of species and species concepts are theoretically debated for some time (e.g., de Queiros, 2007; Sites & Marshall, 2003, 2004; Wiens, 2004, 2007), it is interesting to see how ENM is used to shed light from a more practical point of view. In the paper of Rissler & Apocada the distribution of different 'lineages' of a lizard is analyzed, using phylogenetic methods and bioclimate data. It includes a figure with spatial representation of the several lineages, using GeoPhyloBuilder (unfortunately only working with ArcGIS; why not cross-platform and for general GIS software??). With ENM the contact zones between the different lineages are visualized and they argue that genetic and ecological data prove to be more convincing than morphological differences between lineages. They suggest that future phylogeographic and biogeographic analyses will be more explicitly concerned with spatial and geographic components of genetic variation and speciation than is currently evident. This is certainly a challenge for Neotropical malacology.
I was even more charmed by the paper of Raxworthy et al., who deal with geckos from Madagascar. They use ENM (Maxent; review here) to identify erroneous localities (which could also be the consequence of misidentifications in collections or literature) and develop a method for comparing niche models based on split and lumped taxonomic groupings. In this study they use this method for species delimitation and unveil a cryptic species. Morphological or molecular data were used to guide for partitioning localities between suspected species. Subsequently, using both the lumped and split taxonomic groupings, niche models were compared for predictive performance. They conclude that ENM is especially useful for species delimitation in groups that show high levels of local endemism or include cryptic species which show little morphological and molecular divergence.
Their phylogenetic analyses were done using ethanol 70% and formalin-fixed specimens from museum collections. I wonder if this method would work also in snails...
References:
Raxworthy, C. J., C.M. Ingram, N. Rabibisoa & R.G. Pearson. (2007). Applications of ecological niche modeling for species delimitation: a review and empirical evalutation using day geckos (Phelsuma) from Madagascar. Systematic Biology, 56, 907-923.
Rissler, L. J. & J. J. Apodaca (2007). Adding more ecology into species delimitation: ecological niche models and phylogeography help define cryptic species in the Black Salamander (Aneides flavipunctatus). Systematic Biology, 56, 924-942.
Further references:
de Queiroz, K. (2007). Species concepts and species delimitation. Systematic Biology, 56, 879-886.
Sites, J. W. & J. C. Marshall (2003). Delimiting species: a Renaissance issue in systematic biology. Trends in Ecology and Evolution, 18, 462-470.
Sites, J. W. & J. C. Marshall (2004). Operational criteria for delimiting species. Annual Review Ecology Evolution Systematics, 35, 199-227.
Wiens, J. J. (2004). Speciation and ecology revisited: phylogenetic niche conservatism and the origin of species. Evolution, 58, 193-197.
Wiens, J.J. (2007). Species delimitation: new approaches for discovering diversity. Systematic Biology, 56, 875-878.
Blogging about molluscs
09-02-2008 23:35
Always thought that malacology is a popular topic
(the NMV alone has more than 600 members), but
apparently blogging among malacologists is not very
popular at all. When I just joined Nature Blog
Network I found out that only 3 other blogs are
listed in the molluscs section.
Just do me a favour and return regularly, to give me a higher ranking :-)
Just do me a favour and return regularly, to give me a higher ranking :-)
The new Tentacle is out
09-02-2008 21:09
A bit sluggish, I must admit, but the yearly
newsletter of the
IUCN/Species Survival Commission -
Mollusc Specialist Group
(wow, could it be lengthier?) is out since a few
weeks.
Number 16 has some interesting stuff:
- Land snail diversity and centres of botanical endemism: Dai Herbert and Adnan Moussalli make the interesting observation that areas recognized by botanists as rich in endemics, also harbour a rich diversity of land snails. They write: "From a biogeographical perspective it is easy to appreciate that the historical environmental processes that have created these local foci of plant endemism could likewise underpin similar foci of land snail endemism". I completely agree, but this line of thought also reminds me on the reviled works of Croizat*.
- Tracking land snail extinctions from space: Menno Schilthuizen and Reuben Clements argue on the basis of observations of snails from Malaysia, that it would be worthwhile to use remote sensing to monitor extinction processes by biotope destruction. While their paper focusses on limestone outcrops and karst snails, I immediately had to think about what Eugenia Salas told me about Argentina. During her fieldwork she discovered that several localities where Spixia had been reported from literature, had been destroyed due to the conversion to agricultural use. Threats to land snails are manifold as part of the biodiversity crisis that we face.
- Non-marine mollusc diversity in Paraná State, southern Brazil: Ignacio Agudo discusses the number of land and freshwater snails and bivalves. He mentions only families, treating Bulimulidae, Amphibulimidae and Odontostomidae as distinct. In Paraná, with 9000 km2 a relatively small state, 17, 1 and 5 species are recognized respectively. Simone** lists for the Bulimulidae 176, Amphibulimidae 20 and Odontostomidae 88 species for Brazil.
- From malacological data to analysis: Péter Sólymos has written an extension for the statiscal R-package, called "mefa" (metafaunistics). It could be a nice supplement to StatCrunch, and as it is freeware it is defenitely worth a try. To be continued in a later post.
References
* L. Croizat (1958) Panbiogeography, I, IIa, IIb. Caracas: published by author; L. Croizat (1962 [1964]) Space, time, form: the biological synthesis. Caracas: published by author.
** Simone, L.R.L. (2006) Land and freshwater molluscs of Brazil. Sao Paulo: EGB, Fapesp.
Number 16 has some interesting stuff:
- Land snail diversity and centres of botanical endemism: Dai Herbert and Adnan Moussalli make the interesting observation that areas recognized by botanists as rich in endemics, also harbour a rich diversity of land snails. They write: "From a biogeographical perspective it is easy to appreciate that the historical environmental processes that have created these local foci of plant endemism could likewise underpin similar foci of land snail endemism". I completely agree, but this line of thought also reminds me on the reviled works of Croizat*.
- Tracking land snail extinctions from space: Menno Schilthuizen and Reuben Clements argue on the basis of observations of snails from Malaysia, that it would be worthwhile to use remote sensing to monitor extinction processes by biotope destruction. While their paper focusses on limestone outcrops and karst snails, I immediately had to think about what Eugenia Salas told me about Argentina. During her fieldwork she discovered that several localities where Spixia had been reported from literature, had been destroyed due to the conversion to agricultural use. Threats to land snails are manifold as part of the biodiversity crisis that we face.
- Non-marine mollusc diversity in Paraná State, southern Brazil: Ignacio Agudo discusses the number of land and freshwater snails and bivalves. He mentions only families, treating Bulimulidae, Amphibulimidae and Odontostomidae as distinct. In Paraná, with 9000 km2 a relatively small state, 17, 1 and 5 species are recognized respectively. Simone** lists for the Bulimulidae 176, Amphibulimidae 20 and Odontostomidae 88 species for Brazil.
- From malacological data to analysis: Péter Sólymos has written an extension for the statiscal R-package, called "mefa" (metafaunistics). It could be a nice supplement to StatCrunch, and as it is freeware it is defenitely worth a try. To be continued in a later post.
References
* L. Croizat (1958) Panbiogeography, I, IIa, IIb. Caracas: published by author; L. Croizat (1962 [1964]) Space, time, form: the biological synthesis. Caracas: published by author.
** Simone, L.R.L. (2006) Land and freshwater molluscs of Brazil. Sao Paulo: EGB, Fapesp.
Photo of the day
09-02-2008 17:32
Perhaps this will become a new thread, not sure
yet... After all, there are not so much new pictures
on Orthalicidae, at least not a daily basis :-)
This I found on a web site dedicated to Liguus in Florida. In human sexology it would be called interracial, in malacology intergenerical??
Liguus fasciatus (Müller, 1774) and Orthalicus floridensus Pilsbry, 1899 mating (photo: Phil Poland)
This I found on a web site dedicated to Liguus in Florida. In human sexology it would be called interracial, in malacology intergenerical??
Liguus fasciatus (Müller, 1774) and Orthalicus floridensus Pilsbry, 1899 mating (photo: Phil Poland)
Meeting a soulsister
07-02-2008 13:58
Today is one of those days that you will memorize for
a long time, because it is not so often that you meet
someone with whom you share your passion for the same
group of snails. I had the long-expected meeting with
Eugenia Salas Oroño, a young Argentinan malacologist.
We had been in email contact over the past months, after her publication on Spixia (*).
Spixia pyriformis
(Pilsbry, 1901). Photo: E. Salas Oroño
It soon became clear to me that she is a student of Gabriela Cuezzo at the University of Tucumán. Working on her Ph.D., we exchanged some emails when she announced to have received a German fellowship for a 3 months stay, that would bring her to Frankfurt, Berlin and Munich. Although we initially agreed to meet in Cologne, she decided to spend some free days in Amsterdam and eventually we met there.
The hours filled up very easily, talking about her research, visit to Germany and malacology in Argentina. One of the remarkable observations was that the majority of Latin American land snail malacologists is women. Just a matter of coincidence or is there also a cultural thing?
Time for departure became far too quickly, but I hope that it will be possible to reunion. All the best, Eugenia!
* Reference:
Salas Oroño, E. (2007). Taxonomic review of the Spixia pyriformis species complex (Gastropoda: Pulmonata: Odontostominae). Zootaxa, 1498, 1-25.
We had been in email contact over the past months, after her publication on Spixia (*).
Spixia pyriformis
(Pilsbry, 1901). Photo: E. Salas Oroño
It soon became clear to me that she is a student of Gabriela Cuezzo at the University of Tucumán. Working on her Ph.D., we exchanged some emails when she announced to have received a German fellowship for a 3 months stay, that would bring her to Frankfurt, Berlin and Munich. Although we initially agreed to meet in Cologne, she decided to spend some free days in Amsterdam and eventually we met there.
The hours filled up very easily, talking about her research, visit to Germany and malacology in Argentina. One of the remarkable observations was that the majority of Latin American land snail malacologists is women. Just a matter of coincidence or is there also a cultural thing?
Time for departure became far too quickly, but I hope that it will be possible to reunion. All the best, Eugenia!
* Reference:
Salas Oroño, E. (2007). Taxonomic review of the Spixia pyriformis species complex (Gastropoda: Pulmonata: Odontostominae). Zootaxa, 1498, 1-25.
The Holy Grail of malacohistory
06-02-2008 10:24
Just by accident, I stumbled on a publication by Gene
Coan, Alan Kabat and Richard Petit, entitled
"2400 years of
malacology".
This paper provides a comprehensive catalog of
biographical and bibliographical publications for
over 7,000 malacologists, conchologists,
paleontologists, and others with an interest in
mollusks, from Aristotle to the present. WOW! This
is highly informative and an absolute masterpiece!
Now, my biohistorical notes seems only futile...
Now, my biohistorical notes seems only futile...
Graphing populations
03-02-2008 21:40
One of the topics that I have been wrestling with
since quite some time, is how to deal with statistics
and graphing of populations (and other data as well).
Today I may have found a solution that will work for
me.
Especially when dealing with different populations of a species, one might consider taking various measurements with a marking gauge and calculate some ratios. Unlike the 'old days', there are now light-weight digital gauges (I bought one earlier this week), that make measuring a shell relatively a snap. And instead of jotting down the data with pencil on a sheet of paper, it's much more convenient now to fill in a worksheet of Excel (or what I prefer, Numbers). I like this part of my life to be digitally.
But to do some statistics on them and to make graphs that show to what extent populations differ from each other was long time problematic for me. Unable to afford a de-facto standard like SPSS (not to speak of the ability to handle it), I have been looking for a nifty piece of software that will run on my Mac. Until I found today StatCrunch, a web-based tool that fitted my needs: it is nearly for free (US$ 5/half a year), can handle different inputs (file, copy-paste, URL), does both calculations and graphing, is very flexible in its outputs and stores your results for easy retrieving afterwards.
I had a very suitable problem for a test run today. Thaumastus alutaceus (Reeve) is a rather small Bulimulid from Central Peru, where I had 4 different populations, ranging from 2950-3600m:
When I took the measurements, it was immediately clear that one population was different. But I was unsure how different it was, until I tried some of the options in StatCrunch. Here is one of the results I obtained:
I don't know yet if this output is acceptable for printing, but surely it is good enough for presentations. Anyhow, what was interesting that one population (3) clearly differentiates from the others (in some other ratios as well).
Despite the fact that StatCrunch does not accept input from Numbers, only from Excel (and for me Microsoft sucks), it gets a 5-star ranking!
Especially when dealing with different populations of a species, one might consider taking various measurements with a marking gauge and calculate some ratios. Unlike the 'old days', there are now light-weight digital gauges (I bought one earlier this week), that make measuring a shell relatively a snap. And instead of jotting down the data with pencil on a sheet of paper, it's much more convenient now to fill in a worksheet of Excel (or what I prefer, Numbers). I like this part of my life to be digitally.
But to do some statistics on them and to make graphs that show to what extent populations differ from each other was long time problematic for me. Unable to afford a de-facto standard like SPSS (not to speak of the ability to handle it), I have been looking for a nifty piece of software that will run on my Mac. Until I found today StatCrunch, a web-based tool that fitted my needs: it is nearly for free (US$ 5/half a year), can handle different inputs (file, copy-paste, URL), does both calculations and graphing, is very flexible in its outputs and stores your results for easy retrieving afterwards.
I had a very suitable problem for a test run today. Thaumastus alutaceus (Reeve) is a rather small Bulimulid from Central Peru, where I had 4 different populations, ranging from 2950-3600m:
When I took the measurements, it was immediately clear that one population was different. But I was unsure how different it was, until I tried some of the options in StatCrunch. Here is one of the results I obtained:
I don't know yet if this output is acceptable for printing, but surely it is good enough for presentations. Anyhow, what was interesting that one population (3) clearly differentiates from the others (in some other ratios as well).
Despite the fact that StatCrunch does not accept input from Numbers, only from Excel (and for me Microsoft sucks), it gets a 5-star ranking!