Biology Reference
In-Depth Information
Mean(H expected)
Mean(H expected) is the heterozygosity estimated from allele frequencies at
all loci according to Hardy-Weinberg expectations (e.g., see Hedrick 2010;
Allendorf and Luikart 2007):
m
∑
p
i
2
expected heterozygosity =
H
=
1
−
1
where p
i
is the frequency of the i
th
of m alleles. Expected heterozygosity is
reported as the mean across runs for a given trial of expected heterozygosity
calculated for each cohort, and then for the entire population at each age
of the trial.
Sd(H expected)
For a given trial, Sd(H expected) is the s.d. of the expected heterozygosity
mean value for each cohort and each total population across runs for each
age of the population.
Mean(Fcalc)
As noted earlier, the F value is a measure of the degree of inbreeding and/
or subdivision (Wahlund effect) in the population. The F statistical formula
used by NEWGARDEN is
F = (He - Ho)/He
where He = level of mean heterozygosity expected (expected heterozygosity)
under the Hardy-Weinberg equilibrium formula calculated from allele
frequencies across loci;
and Ho = mean level of actually observed heterozygosity calculated
from all loci of all individuals in the population.
At the end of most examples given in this topic, F ranges from 0 (no
inbreeding and/or subdivision) to 1 (high inbreeding and/or subdivision),
although F can also be negative, for example, when there is an excess of
heterozygosity above that expected. F refl ects the deviation of the observed
heterozygosity from that expected due to Hardy-Weinberg equilibrium.
For example, if, as a population develops, the decrease in observed
heterozygosity is greater than the decrease in the expected heterozygosity,
then inbreeding and/or population subdivision is occurring. F values from
0.05 to 0.15 are often taken as indicating moderate inbreeding/subdivision;
from 0.15 to 0.25 as great inbreeding/subdivision; and greater than 0.25 as
very great inbreeding/subdivision (e.g., Conner and Hartl 2004).
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