Re: Built Like a Race Horse, Slow as an Elephant?

[John Wilkins <j.wilkins1@uq.edu.au>]

On 17/01/2007, at 2:25 PM, Sim Koning wrote:

> <j.wilkins1@uq.edu.au> wrote
>
> > Whether or not herd animals are "competing" with each other or  
> > are  hunted individually, the arms race must be intraspecies.
>
> I don't mean to nitpick, bur don’t you mean interspecies, because  
> intra means within one, not between two.

Good catch. Thinko...
> But anyway I completely understand everything you said, I was  
> thinking about that on my way home and this clears some things up  
> for me. In retrospect I realize I didn't think my post through  
> before I typed it. But anyway, to be fair, An arms race, or any  
> race for that matter, is a type of competition, so I think it would  
> make more sense to say, interspecific and intraspecific  
> competition. Dann would be just as correct in saying there is an  
> “arms race” between two members of the same species as he would be  
> saying there is an "arms race" between predator and prey. "Arms  
> race" is just a metaphor for competition anyway, since I don’t  
> exactly think cats and antelopes are actually building nuclear  
> weapons and fighter jets. Again I know I'm nitpicking, this is just  
> semantics and I understand your point.

I'm a philosopher. Picking nits is professional courtesy and  
semantics is the fleas. The metaphor of "arms race" implies offence  
and defence on the part of the competitors. While it may be true that  
a variant within a species is competing, this is like a race rather  
than a boxing match. Predators and prey attack and defend -  
intraspecific competitors merely try to outrace. As I recall the  
origination of the metaphor, in Dawkins and Krebs 1979 article, they  
did allow for intraspecific arms races, but not for environmental  
selection, but for, say gender conflict, mate competition, or sex  
ratios. Looking it up now, I find this comment:

"Bit it [intraspecific arms race] is an arms race between two  
branches of the same conditional strategy, not an arms race between  
two independent lineages with separate gene pools." [p500]

Dawkins, R, and JR Krebs. "Arms Races between and within Species."  
Proceedings of the Royal Society of London, Series B 205 (1979): 489– 
511.

> > --- Dann Pigdon <dannj@alphalink.com.au> wrote:
> > Actually, it was almost certainly a
> > pronghorn/pronghorn arms race. There would always have been far   
> > more pronghorns than
> > cheetahs, so cheetah predation on a population of slow coaches  would
> > still not have been enough to threaten their long-term survival.
>
>   I don’t exactly agree with this. If cheetahs could easily catch  
> all members of their prey species, then less cheetahs would starve,  
> which would increase the number of cheetahs, which in turn would  
> decrease the number of prey. The same would be true in reverse, if  
> the prey was too fast for any cheetah to catch, then the cheetahs  
> would starve and the prey species would overpopulate. This is where  
> the “arms race” comes in, as Wilkins explained. Equilibrium is  
> maintained between the two species. Now there are cases where a new  
> predator species is introduced into an ecosystem that is far faster  
> or deadlier than what a prey species is adapted to cope with, if  
> the prey species can’t adapt fast enough to cope, it will go  
> extinct. So in other words, there are cases where the so called  
> "arms race" is lost.

Invasive species upset the "balance of power" as it were, whether  
predator or niche competitor for prey species. So you get a period of  
bellum omnia contra omnes for a while until a new balance is reached,  
or the ecosystem collapses and a new one is constructed.
--
John S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project
University of Queensland - Blog: scienceblogs.com/evolvingthoughts
"Darwin's theory has no more to do with philosophy than any other
hypothesis in natural science." Tractatus 4.1122