[ExI] The actual Sahney paper vs. the BBC's pop-sci collectivist interpretation

[lists1 at evil-genius.com]

http://www.bbc.co.uk/news/science-environment-11063939 said:
> the amount of biodiversity closely matched the availability of "living 
> space" through time.
E. O. Wilson proved this decades ago.  It's a well-known rule of thumb 
that 2x the species diversity requires 10x the area.
> The new study proposes that really big evolutionary changes happen 
> when animals move into empty areas of living space, not occupied by 
> other animals. 
That is absolutely not the same thing as saying "competition did not 
play a big role in the overall pattern of evolution".  Creatures are 
competing with others of their species, and with others who use the same 
resources within their existing environmental niche.
>
> "For example, even though mammals lived beside dinosaurs for 60 
> million years, they were not able to out-compete the dominant 
> reptiles. But when the dinosaurs went extinct, mammals quickly filled 
> the empty niches they left and today mammals dominate the land," he 
> told BBC News.
>

Yes, the availability of a new niche increases the range of possible 
beneficial variations for your offspring: being a large predatory mammal 
(like, say, a lion) isn't very useful when there are dinosaurs around.  
However, this is a difference of degree, not of kind.

I looked up the original paper, which I cannot find in full-text form 
(just the abstract):
http://www.ncbi.nlm.nih.gov/pubmed/20106856

The abstract concludes " These groups have driven ecological diversity 
by expansion and contraction of occupied ecospace, rather than by direct 
competition within existing ecospace and each group has used ecospace at 
a greater rate than their predecessors."

It is most likely true that availability of ecological niches is a 
constraining factor for useful genetic variation (and, therefore, 
speciation), which appears to be the true subject of the paper.  
However, it is also true that differential survival (and, therefore, 
competition) occurs by definition, since not all living things leave 
offspring, and of their offspring, not all survive.

And, Dawkins also clearly showed in "The Extended Phenotype" that 
ecological niches, "ecospace", and/or "the environment" are defined in 
large part by the phenotypic effects of the existing life within said niche.

Therefore -- by the definition of the basic mechanisms of evolution -- 
competition is still the driving factor in evolution, and the BBC 
article summarizing this paper comes to an erroneous conclusion, most 
likely in an effort to push a personal agenda of the writer.

What the paper does demonstrate is that whether a niche is previously 
occupied tends to be the constraining factor in biological evolution.  
In other words, just like real-world economics, barriers to entry 
prevent the theoretical free market from existing except in the case of 
disruptive technological innovation that opens an unoccupied competitive 
space.

-G