"Representative Trantis"  wrote in message
>
> Why is it so frowned upon to propose the idea that an animal can get
> worse, before it gets better. It is not inconcieveable that an animal
> could get worse at doing a job, but because there are no predators,
> etc, it doesn't die out.
>
There are lots of examples of birds which have become flightless because
they live on islands with few predators.
What is harder to determine is, are they flightless because not investing
energy in flight means that they can spend it on other things, such as
making eggs, so flightlessness is actually more adaptive, or is the reason
that, given a thousand random mutations, 999 will make flight worse and only
1 make flight better, so flight deteriorates by drift?
>
> Or is it the case that in the wild a creature will only get enough food to
> be able to survive, so must be the best it can be at it's job?
>
Something has got to limit the numbers of every species. Food is an obvious
candidate, but this doesn't mean that the population is perpetually on the
edge of starvation. If you have a bad season every ten years, there could be
a big die-off then, with numbers gradually increasing in the plentiful years
in between.
There might also be a tension between gathering food optimally and surviving
famine. Let's say there are two alleles, "fatty" and
"fitty". Fatties have
an extra layer of fat, which means that they can survive a bad winter, but
also means that they can't gather food as quickly as fitties. During the
years of plenty, both will survive but the fitties will have more offspring.
During the lean years, fatties will have higher survival rates. By tweaking
the parameters, you would see different patterns of genes emerge.
>
> [moderator's note: I have thought about this myself: the adaptationist
> ideal is that mere adequacy must be optimized -- that is, one must be
> optimal just to persist. Is this true? - JAH]
>
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