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Islands and spiders and arthropods, oh my!

October 30, 2009

Dilettante has been a very busy girl.  What with raising a toddler, falling pregnant again and starting a new research position, her blog activity has been poorly neglected.  However a recent foray into writing some journal papers has inspired her to put her writer’s smock on again and get dilettanting.

When last we met I had spun up Portugal as the country of choice – today I randomly selected an institution of choice.  The lucky (debatable) winner was established in 1976 after the Portugese revolution of ’74.  It is primarily located in the west of Portugal and has three campuses with the main one located in Ponta Delgada.  This institution specialises in a fair amount of the sciences, as well as the social sciences and literature.  One of the campuses focuses on agricultural sciences, while a second focuses on oceanography and fisheries.  The main campus encompasses all other departments.  It is:

Universidade dos Acores (or The University of Azores)

The paper chosen is one of those ‘future’ ones published a few months (in this case November) before the hardcopy issue comes out – I love those.  It is:

Cardoso, P., Borges, P.A.V., Veech, J.A., (2009), Testing the performance of beta diversity measures based on incidence data: the robustness to undersampling, Diversity and Distributions, 15(6), 1081-1090.

And Dilettante now lets out a deep sigh about reviewing a biology type paper – because she is no expert in the area, but then that is what dilettanting is all about!

The paper focuses on studying diversity in spiders and arthropods (Dilettante is already shivering) and asks why many researchers in the area of beta diversity do not typically worry about having a complete list of species in a studied community and how the level of completeness could affect beta diversity levels.  What – questioning the rigour of other scientists – the nerve!!  Well done Cardoso and co. this is what it is all about – questioning what is known and trying to add to the pool of knowledge.  I only wish I had the nerve sometimes – although it comes out when necessary.

Anyway back to the spiders and arthropods (which I must admit is very appropriate for Halloween):

Portugal1

Would not like to meet this in a beta diversity study

Beta diversity apparently looks at the turnover of species between communities, but somehow there is no widely accepted measure of it.  Working with populations I guess it can get quite difficult when you have larger communities.  This study tried to address the problem by evaluating measures of beta diversity that focus on dissimilarity of population compositions between pairs of communities rather than trying to complicate the issue with three or more communities.  Good approach start little, work up to big.

The focus was on incidence data, not on abundance data – I think this means that they were looking at diversity but not the amount by which the community was ‘diverse’ (but then I am no biologist, ecologist, entomologist, whatever you have to be to study this stuff).    Some pretty formulae that aren’t too complicated were used to quantify the beta diversity index and some modifications were used by the authors on existing formulae to allow for problems they felt needed to be addressed.

The upshot of the entire study was to develop a sampling method and quantification of beta diversity that would truly represent the diversity within the entire communities.  Population statistics at its most ambitious.  The authors feel they achieved this and proposed a set of conditions for the use of each of the different types of beta indices (and their relevant formulae).  I am not sure of the quality of this work, but it sounds pretty good to me, as often there is no single answer to the question….

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