EnviroSpin Watch

Back to biogeographical basics (environmental reporters please note).....

Here is a short but thoughtful comment, and useful link to a penetrating longer article, both by Jon Christensen, a Research Fellow in the Center for Environmental Science and Policy, Stanford University, over at The Uneasy Chair blog: 'What if we're wrong' (Conservation in Practice, Oct-Dec 2005 Vol. 6 No. 4).

In the latter, Jon recalls seven assertions, based on recent biogeographical research, challenging current theory made by the eminent New Mexican biogeographer, Professor James H. Brown, an absolute leader in his field:

1. Species diversity of most taxa inhabiting islands and insular habitats is far from a dynamic equilibrium between opposing rates of colonization and extinction;

2. Much, perhaps most, speciation is not allopatric;

3. Different taxonomic groups living together in the same place usually do not have congruent biogeographic histories;

4. Range shifts in response to major geological and environmental changes have not been unidirectional and coincident across different species, lineages, and functional groups;

5. Diversity of most lineages cannot be explained simply by a difference between speciation and extinction rates;

6. Latitudinal and elevational patterns of diversity are often different;

7. The current rate and magnitude of human-caused global extinctions are not the greatest in Earth history.

As an 'old' biogeographer myself, I would agree with all of these points. Indeed, I very much hope that, as Jon avers in his blog, we are experiencing a paradigm shift, for, as Professor Brown himself declared at the inaugural meeting of The International Biogeography Society (IBS): "Much current biogeographic theory is either wrong, too simplistic, or relevant to only specific instances..."

Watch this space you environmental reporters who have assumed so much ...

Philip, who always argues [along with Charles Darwin (for it is he!)] that biogeography - geography - is "... that grand subject, that almost keystone of the laws of creation." Time for tea in the parlour, Mrs. D.