One means of estimating the size of a population is a "

A population comprises

(1 / **N**_{e})**
**= **(1 / 4)(1 / N**_{m}) + **(****1
/ 4****)(****1 / N**_{f}**)** =
(1 / **4N**_{m}) + (1 / **4****N**_{f})

To isolate

(1 / **N**_{e})**
**= (1 / **4N**_{m})
+ (1 / **4****N**_{f}) = (**N**_{f}
+ **N**_{m})
/ **4****N**_{m}**N**_{f}

for which the reciprocal is

Check: if the numbers of males and females are
equal, **N**_{m}
= **N**_{f}
= **N** / 2, and from the formula** ****N**_{e}** **= (**4**)(**N**/2)(**N**/2) / (**N**/2 + **N**/2) = (4)(**N**^{2}/4)
/ **N** = **N**

Where the sex ratio of breeding individuals is unequal, this departs rapidly from expectation. In the extreme case with one breeding male, where

© 2022 by **Steven M Carr**