9327

• UCREFRP Catalog Number: 9327
• Author: Starnes, W. C.
• USFW Year: 1995.
• Copyright Material: NO

However, few other loci approach significant levels of deviation
and the lack of corroborating deviations lessens the probability
that populations represented by these samples actually are at
varience with Hardy-Weinberg expectations overall. Average P
values are somewhat depressed in a few but not all the samples
concerned. Assortive mating is therefore not strongly supported
and, while heterozygosity is low in several lower basin samples,
the lack of corroboration at other loci for the repeated
deficiencies at EST-2, and the fact that two classes of
homozygotes rather than one occur, point away from bottleneck
effects as the causative factor for the data configuration at
that locus.
Inspection of class frequencies and coefficients for
heterozygote deficiency for EST-2 in Table 6 indicates. that there
are severe deficiencies of expected heterozygotes in most of the
aforementioned twelve samples. Because other loci do not
corroborate the possibility of assortative mating occurring,
other explanations must be sought. Such data configurations
might result from the presence of null alleles, post-
transformational modifications, artifacts of methodology, or
scoring misinterpretations. Null alleles, which are known for
EST-2 (e.g., Selander, 1970), do not express a product
electrophoretically and are invisible as homozygotes;
heterozygotes express only the alternate allele and may thus be
indistinguishable from homozyotes for that alternate allele. They
can thus alter scoring of the true representation of both
alleles. Post-translational phenomena are the result of
modifications (such as deamidization???) to enzyme molecules
brought about by physiological or environmental conditions which
can alter that molecule's electrophoretic mobility (cite?????).
Methodological artifacts could be alterations in molecular
structure induced at the time of sampling or in preparation of
the sample for electrophoresis.
If null alleles were involved, say in combination with two
other normally expressing alleles to result in two visible
mobilities, one would expect at least a few homozygotes (thus
invisible and unscorable) for the null allele to occur across all
the samples which total hundreds of individuals. This is not the
case as virtually all individuals run were scorable except three
in one sample. Also, some heterozygotes of the two visable
alleles would still be expected and these are rare or absent.
However, if that null allele were lethal as homozygotes, for
example, because an essential enzyme was not produced, but
heterozygotes were adequately fit, only heterozygotes would be
represented in samples. Further, if that allele occurred at a
much higher frequency in the population compared to the visable
alleles, most surviving individuals would be heterozygotes for
the null allele plus one or other of the visable alleles and
would thus be unknowningly scored as homozygotes, along with the
few actual homozygotes, for the visable alleles involved, as
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