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Re: Dinosaurs to birds--Survival Rates
In a message dated 1/24/99 12:16:57 AM Eastern Standard Time,
<< If the probability of an individual surviving is, say, one in a
>million, and the population is ten thousand, then one would expect the
>population to be destroyed. But if the population is ten million, then one
>would expect about ten individuals to survive. >>
In a random environment such as the lottery, you'd be correct on average,
though any single trial could vary a great deal from the average. However, in
a situation in which survival depends on conditions in a small geographic area
I expect that other factors would be involved.
For example, say a cloud of poison gas covers an entire area except for a
single sheltered valley. If the 10,000 are herd animals and many are in that
valley, thousands would survive. If the 10,000,000 are spread thinly over the
entire area, perhaps a few hundred might be in the valley and survive.
The other part of the problem, for me, is breeding populations: if a single
breeding pair survived the genetic variation would be small and, as I
understand it, the chances for survival would also be small. The cheetahs
mentioned previously are an example. Therefore, wouldn't a species' survival
imply that a large number of individuals had survived?