# Effective population size

The effective population size ( )${\ displaystyle N_ {e}}$ is a unit in biology which u. a. is used to the minimum viable population to calculate (MVP = minimum viable population).

## properties

The effective population size is based on the reproduction rate of an idealized population with a random allele distribution. The overall size of a population can be misleading because not all members of the population can reproduce and pass their alleles on to the next generation . In order to make a meaningful estimate of the smallest viable population, the effective population size is calculated using the following formula:

${\ displaystyle N_ {e} = {4N_ {f} N_ {m} \ over N_ {f} + N_ {m}}}$

Here stand for the number of females in the population and for the number of males in the population. ${\ displaystyle N_ {f}}$${\ displaystyle N_ {m}}$

For example, if there are 400 reproductive females and 400 reproductive males in a population of 1000 individuals, then calculates

${\ displaystyle N_ {e}}$ = (4 × 400 × 400) / (400 + 400) = 800 (or 80%).

In populations that are actually examined, this amounts to only a fraction of the total population, as numerous influences act on the individuals and limit their ability to reproduce. ${\ displaystyle N_ {e}}$

The goal of maintaining an in excess of minimum viable population is (MVP), was born from the concern is whether populations sufficient genetic variability have to get through evolution to adapt. ${\ displaystyle N_ {e}}$

## Individual evidence

1. ^ B. Charlesworth: Fundamental concepts in genetics: effective population size and patterns of molecular evolution and variation. In: Nature Reviews Genetics . Volume 10, Number 3, March 2009, pp. 195-205, . doi : 10.1038 / nrg2526 . PMID 19204717 .
2. M. Woolfit: Effective population size and the rate and pattern of nucleotide substitutions. In: Biology letters. Volume 5, Number 3, June 2009, pp. 417-420, . doi : 10.1098 / rsbl.2009.0155 . PMID 19364708 . PMC 2679941 (free full text).