Biology Reference
In-Depth Information
<locus>
<dpdpoint x=“0.1” y=“0”/>
<dpdpoint x=“0.1” y=“1”/>
<dpdpoint x=“0.1” y=“2”/>
<dpdpoint x=“0.1” y=“3”/>
<dpdpoint x=“0.1” y=“4”/>
<dpdpoint x=“0.1” y=“5”/>
<dpdpoint x=“0.1” y=“6”/>
<dpdpoint x=“0.1” y=“7”/>
<dpdpoint x=“0.1” y=“8”/>
<dpdpoint x=“0.1” y=“9”/>
</locus>
In NEWGARDEN input, the above code can alternatively be written as
follows:
<LOCI number_loci=“0” auto_alleles_per_locus=“10” number_automatic_
loci=“1”/>
which is useful for cases where all unique alleles at a locus (or several
automatic loci), in this case 10 alleles, have the same frequency.
Compared to the case discussed above of two unique alleles of equal
frequency, where we need to draw 10 or 20 founders to be reasonably sure
of including both alleles in the founding population, with 10 unique alleles
of equal frequency in the source population, the number of founders needed
to ensure that all 10 unique alleles are represented at least once among the
colonizers jumps to 40 to 100 (Fig. 7.5). This conclusion is supported by the
results depicted in Fig. 7.6, where standard deviation in these trials does not
approach 0 until approximately 40 or more founders are drawn from the
source population. Obviously, some unique alleles will always be lost in a
founding population with fewer than fi ve diploid founders (that is, fewer
than 10 draws of alleles), but apparently approximately 80 allelic draws (40
founders) are needed to be reasonably certain of including all 10 unique
source-population alleles among the founders.
Expected heterozygosity (gene diversity) for a locus can be calculated
as:
m
∑
p
i
2
H
=
1
−
1
where p
i
is the frequency of the i
th
of m alleles (e.g., Freeland 2005: 72).
For the source population in Hardy-Weinberg equilibrium, expected H
would thus equal 0.9. Figure 7.7 demonstrates, using NEWGARDEN-
generated data from our current example of considering one locus with
10 unique alleles all at frequency = 0.1 in the source population, that as
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