Re: Minimum number of males in a breeding population


baal wrote:
What is the minimum number of males in a breeding population of 10,000
needed to avoid fatal inbreeding

That has actually been calculated. It was published in either Science
or Nature, but I can't remember the citation. It was mainly about
endangered species and was a statistical exercise. The answer came out
to be an "effective" breeding population of 10,000 was needed. This is
5,000 males and 5,000 females that are producing the next generation.
It doesn't include the members of the population that do not reproduce.
The fewer the breeding males the smaller the effective population size
is even if the breeding population is 10,000. When the ratio hits some
number like 1 male to 10 females the effective population size is
essentially the number of males, when you take inbreeding into account
it can be even lower. There may be millions of dairy cattle in the US,
but due to the use of artificial insemination and the inbreeding of the
Holstein herd, I've heard that the effective population size is only 20
or so. Live calves have gone from one with less than two inseminations
to one in three inseminations. This is likely due to inbreeding
depression.

Now, a population of less than 10,000 doesn't gaurantee that a
population is destined for genomic meltdown, just that it is more
likely than not. Obviously many populations and species started with
effective population sizes smaller than 10,000. Just as obviously the
vast majority of species ar extinct. You have to deal with
distributions and how many populations make it even if the vast
majority don't.

Ron Okimoto

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