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7.4.6 Founder Genome Equivalents

Lacy ref640 also defined the number of founder genome equivalents ($ f_g$) as a measure of genetic diversity. A founder genome equivalent is the number of founders that would produce a population with the same diversity of founder alleles as the pedigree population assuming all founders contributed equally to each generation of descendants. Founder genome equivalents are calculated as:

$\displaystyle f_g = \dfrac{ 1 } { \sum{ \dfrac{p_i} {r_i} } } $

where $ p_i$ is the proportion of genes contributed by ancestor i to the current population and $ r_i$ is the proportion of founder i's genes that are retained in the current population. Like $ f_e$, $ f_g$ accounts for unequal founder contributions. Unlike $ f_e$, $ f_g$ also accounts for the fraction of founder genomes lost from the pedigree through drift during bottlenecks. Although $ f_g$ is the more accurate description of the amount of founder variation present in a population, it can only be calculated directly for simple pedigrees. For large or complex pedigrees, the number of founder genome equivalents must be approximated based on computer simulation of a large number of segregations through the pedigree. This is done by assigning each founder a unique pair of alleles and randomly transmitting those alleles through the pedigree [MacCluer, VandeBerg, Read, and RyderMacCluer et al.1986]. The number of founder genome equivalents is similar to the effective founder number, but the former has been devalued based on the proportion of its genome that has probably been lost to drift [LacyLacy1989].

Up One Level A Manual for use of PyPedal
A software package for pedigree analysis		 Contents Index
Previous: Up: 7.4 Computational Details Next:
Release 2.0.0rc7, documentation updated on November 29, 2005
Revised May 7, 2008.
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