From: Adam <""4thwormcastfromthemolehill\"{at}the field.near
the bridge">

John Beckett wrote:
> Adam  wrote in message
> news::
>
>>But why should be being chased by cheetahs make the pronghorn antelope fast?
>
>
> Is this a trick question, or is there some faint chance that you are
> seriously asking?
>
> Being chased by cheetahs does not make anything faster. However, any tiny,
> random mutations which cause antelopes to run faster will be rewarded in
> future generations, and those mutations will become more prevalent.
>

Yup. It's the continous pressure placed by a faster predator. Conversely
does the pronghorn getting faster make the cheetah faster?

Feed or die. Be food & die.

& the dead part has to happen before you've had offspring (which
themselves survive).

> Also, cheetahs will never run MUCH faster than their fastest prey. Because
> the effort their bodies spend on being able to go faster than necessary
> would mean that other cheetahs, whose genes didn't bother with the excess
> speed, would be able to develop in other ways (e.g. give birth to more
> young) that would multiply the "slow" genes.
>

Yup. Put em somewhere with sheep & you'll end up with faster sheep
& slower cheetahs.


> I might even tell you about pronking antelopes, but I'm still puzzled
> about what line you are pursuing.
>

The fact that you can look at animals & go "how come it has
that" (e.g. a very high top speed in the abscence of high speed
predators).

It's the old "evidence of evolutionary pressure" thing.

I've seen it here where they have re-introduced buzzards & they have
changed the behaviour (the most malleable factor) of the brown hare
completely. They used to sit in the middle of a field so they could look
all around & they always only had 1/2 a field to cover no matter where
the threat came from. & they used to run in a big circle & come
back to the center if possible.

Now they stay close to woodland & if disturbed make straight for the
nearest trees. In fact they've basically become woodland animals who go out
into the fields at night (unless there is some cover e.g. standing corn).

Adam




Adam

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