... populations¹

Don't forget that stochastic threats are primarily important only after a population is already small and endangered. Deterministic, systematic forces associated with habitat destruction, environmental degradation, invasive exotics, etc. are the most likely causes of population declines.

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... purposes:²

If you want a more complete discussion, refer to chapter 7 of [7] or take my course in population genetics next fall.

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... number³

census number--the number of individuals in a population, simply counting all that are alive

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... number.⁴

effective population size--the size of a population for purposes of genetic drift, adjusted for unequal sex-ratio, age structure, variable population size, and the like.

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... 12.⁵

If you've never heard of a negative binomial distribution before, don't worry about it. All you need to know is that the variance of a negative binomial distribution is larger than that of a Poisson distribution with the same mean. Then $N_e = \frac{2N}{1+(12/2)} \approx 0.28N$.

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... population.⁶

The reasons for this are technical and have to do with the difference between the variance and inbreeding effective size of a population. Ask me if you're interested in the details.

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... require⁷

This calculation is the entire justification for the ``50'' part of the famous (infamous) 50/500 rule.

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... studied⁸

Except those that are known to have survived recent, severe population bottlenecks.

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... result,⁹

And after considerable debate, as you can imagine.

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...Franklin80.¹⁰

The ``500'' part of the 50/500 rule.

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... AFLPs¹¹

The molecular basis of this variation isn't important for our purposes. If you're interested, ask me.

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... history.¹²

Remember, only the Amsterdam albatross shows evidence of recent recovery from a bottleneck. The wandering albatross has substantially larger populations.

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