Re: Biodiversity and the fossil record

[Mike Melchin <mmelchin@xxxxxxxxxxxxxx>]

On Fri, 15 Mar 1996, David H Goodwin wrote:

> 
> Greetings all.  I was recently involved in an interesting debate 
> regarding biodiversity.  Many students were lamenting the current state 
> of declining biodiversity.  I mentioned that in an abstract way human 
> perturbations of the Earth's ecosystems are akin to other stochastic 
> processes, ie. Boloid impacts, climate change and sea level fluctuations. 
> I was not advocating a suicidal mindset where we do not concern ourselves 
> with environmental/ecological problems.  
> 
> However, as paleontologists we have perhaps the greatest insight 
> into the implications of decreasing biodiversity.  
> 
> So here is the question for you to kick around:  Based on our knowledge
> of mass extinctions and recoveries -life has always managed to recover, 
> including the big one (Permian/Triassic)- how concerned is the 
> paleontological community regarding the current 'mass extinction'?  
> 
> David Goodwin
> MS Student
> University of Montana
> 
Paleontologists may have a unique prespective on mass extinctions 
from the point of view of their stochastic nature and the 
inevitiable biotic recovery that follows, but that does not mean 
the we want to be responsible for causing one.  After all,
paleontolgists are part of the global biosphere now and dependent on 
it for our existence, not to mention the benefits 
that a diverse biota provide us.  Ecosystems are too complex for 
us to either control or predict the outcome of unwitting 
experiments we may conduct on them.

As paleontologists, we also have a unique perspective on the 
evolution of diversity, which the product of continuing spatial 
and temporal environmental heterogeneity.  We know that 
environmental change is the norm and that models and 
conservation measures that treat ecosystems as equilibrium or 
static entities through time will break down as the physical 
environment changes (this particularly at a time when human 
activities are accellerating these changes as well!).  What is 
the use of a wildlife refuge for example, set aside for posterity 
to preserve a particular habitat and its organisms, which, when 
climate changes or sea level rises, becomes a different habitat 
for which its inhabitants are unsuited.  

Human activity has resulted in reduction in spatial 
heterogeneity and attempts to limit temporal change in some 
situations and dramatically accellerate it others.  I guess that 
one of our challenges is to develop conservation strategies that 
can preserve an environmental heterogeneity that is robust enough 
that longer term changes can result in shifts and readjustments 
of biota (as has been the case in most of Phanerozoic history) 
rather than a series of local ecological collapses.

Mike Melchin, Chair
Geology Dept., St. F.X. University
P.O. Box 5000, Antigonish, N.S., Can
B2G 2W5  902-867-5177, FAX - 902-867-5153
mmelchin@stfx.ca