sep. 2008
Symposium land snails
27-09-2008 21:27
Today the Dutch Malacological Society held a
symposium on land snails, commemorating the 65th
birthday of Prof. Edi Gittenberger
(Naturalis/University Leiden). The programme of the
symposium consisted of lectures by longstanding
friends and colleagues or former PhD-students, all on
various aspects of land snails. My presentation was
on species distribution modeling and was jointly
prepared with Francisco Borrero.
Adri and Edi Gittenberger
At the end of the meeting Edi Gittenberger was awarded a special medal for his nearly 50 years of contributions to malacology. And he was given the first copy of the ‘Gittenberger Festschrift’ of Basteria, in which 32 papers are published by 43 authors, mostly on land molluscs. My contributions can be found here.
Edi Gittenberger glances through his Festschrift. In the background the cover with a similar situation, pictured in 1985.
Adri and Edi Gittenberger
At the end of the meeting Edi Gittenberger was awarded a special medal for his nearly 50 years of contributions to malacology. And he was given the first copy of the ‘Gittenberger Festschrift’ of Basteria, in which 32 papers are published by 43 authors, mostly on land molluscs. My contributions can be found here.
Edi Gittenberger glances through his Festschrift. In the background the cover with a similar situation, pictured in 1985.
Maxent and sample size
12-09-2008 19:05
From earlier posts you may know that I’m a fan of
Maxent. Recently a new paper* appeared in which
different software on species modeling were compared.
This time there was special emphasis on the
performance with the use of a small number of
occurrences. This is usually problematic for many
modeling programs. Here is the result: Maxent has
about “the best predictive power across all samples
sizes”.
This is certainly good news, but it doesn’t solve a problem what I have with the modeling of endemic, range-restricted species. These are usually known from very few localities (up to 4). So far, I haven’t seen solutions proposed for working with these small numbers. But if anybody has an idea for an approach that could solve this nifty problem, please keep me posted! You would certainly make my day.
Reference:
Wisz, M. S., Hijmans, R.J., Li, J., Peterson, A.T., Graham, C.H., Guisan, A. & NCEAS Working Group (2008). Effects of sample size on the performance of species distribution models. Diversity and Distributions, 14, 763-773.
This is certainly good news, but it doesn’t solve a problem what I have with the modeling of endemic, range-restricted species. These are usually known from very few localities (up to 4). So far, I haven’t seen solutions proposed for working with these small numbers. But if anybody has an idea for an approach that could solve this nifty problem, please keep me posted! You would certainly make my day.
Reference:
Wisz, M. S., Hijmans, R.J., Li, J., Peterson, A.T., Graham, C.H., Guisan, A. & NCEAS Working Group (2008). Effects of sample size on the performance of species distribution models. Diversity and Distributions, 14, 763-773.
Weyrauch's type localities
01-09-2008 16:42
Early this year I wrote about
Weyrauch,
one of the well-known malacologists dealing with
Neotropical land snails. Recently a paper was
published by Barbosa et al. with a list of all taxa
published by Weyrauch. Unfortunately the type
localities in this list were given only very broadly
defined. For various reasons, e.g. methodological, it
is often desirable to have very precise georeferenced
localities. Therefore I have tried to locate as much
of Weyrauch’s type localities in the list
here.