Re: Herbivore protection

[John Bois <jbois@umd5.umd.edu>]

On Tue, 3 Jun 1997 Wabandco@aol.com wrote:

> John Bois suggests "...clutch size exists to increase Darwinian fitness, not
> to satiate predators...predator satiation needs justification before it can
> be claimed for adaptive value for colonial hadrosaur nests."  I can't help
> but note that we mustn't think of Darwinian selection or any other version of
> evolutionary selection in terms that imply sentience; 

...none implied on my part..

> ...predator satiation
> would be an effect of increased clutch size, 

...not necessarily...

> ...and increased clutch size would thus be Darwinianly fit...because
> those who reproduce in large clutches are more likely to have
> surviving offspring...

I don't think so.  Surviving offspring can be achieved by having smaller
clutch size too.  It is more Darwinianly fit to have one egg survive
(because, perhaps, of your parental investment) than a thousand perish!

> Obviously, the large-clutch laying critter (hadrosaur or any other) doesn't
> intend to satiate the predators; but those herbivores whose clutches are
> large provide the predators with sufficient nutrient to allow some survival,
> and thus, large-clutch herbivores will prevail over time.

I don't understand this.  Surely it would be better to deprive predators
of your offspring altogether.  To hell with 'em!  This reminds me of H. G.
Wells' _The Time Machine_ where the placid peoples march into the caverns
to be eaten.  As long as a few sacrifice themselves the rest live an
idylic life.  Organisms that have no protection against predation may have
selection to either increase clutch size _or_ reduce predation.  I
maintain that a clutch size of 18??? or so for a hadrosaur cannot be
interpreted as a hedge against predation at the nest.  Certainly, if these
creatures all had that many offspring survive the cretaceous would have
been chock-a-block with them.  But whether these numbers were culled at
the nest or beyond is speculation.  However, I argue that satiating
predators in a colony among a predator population greater than that of
bese-level doesn't make sense.  The only decent arguement for this is the
possibility that colonizers are better able to synchronize incubation.
But at an incubation time of at least one month (does anyone argue this)
how critical can timing be?  And aren't there easier ways of doing this.
I mean day length or something.
Finally, large clutch herbivores have not prevailed over time.  Most
large herbivorous animals of today have very small clutches.

> Thus, "...Darwinian fitness..." and "...satiate[d] predators..." go hand in
> hand...

But "...Darwinian fitness..." and "...starving predators..." is OK too.