[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Built Like a Race Horse, Slow as an Elephant?
Andrew Simpson writes:
--- Dann Pigdon <firstname.lastname@example.org> 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 doubt pronghorns would have evolved to run as fast
as a cheetah (or as
close as their biology would have allowed) just to
avoid the occasional bit
of cheetah predation. I think it's more likely that
pronghorns evolved to
run fast to compete with each other.
It's like the old saying goes: if you and a friend
are chased by a tiger,
you don't have to outrun the tiger. You just have to
outrun your friend...
I'm not sure I'm following you Dann. How are the
Pronghorns evolving speed? Are you saying that the
North American Cheetah are or are not responsible?
Because the Proghorns can't make themselves faster and
have no reason too unless something is chasing them or
if there is an advantage to getting somewhere quicker.
(A quickly dwindling food source perhaps).
Cheetahs (and other less speedy predators) are the indirect cause, however
it was almost certainly not an 'arms race' between predator and prey. Where
herd animals are concerned, they only have to out run the slowest members of
the herd. Hence the competition for speediness is between animals of their
own species, not directly between predator and prey.
The evolution of horns seems to have followed a similar pathway. Antelopes
use their horns against each other (or as sexual displays) far more often
than they do defending themselves against predators with them. Therefore the
development of steadily bigger or sharper horns may not have been an 'arms
race' against predators, but rather due to intraspecies interactions.
The only antelope predatory defense that I can think of that seems a direct
response to predation is the practice of pronking. Rather than demonstrate
speed and strength to a predator directly by evading them (a huge waste of
energy), pronking allows an antelope to demonstrate it's fittness to a
predator without excessive energy loss. When an antelope pronks, it is
communicating directly to the predator, rather than competing with herd
GIS / Archaeologist http://www.geocities.com/dannsdinosaurs
Melbourne, Australia http://heretichides.soffiles.com