- in some cases, inheritance of a single allele,
such as the sex-determining factor, will cause
phenotypes to be so different that we can see
which individuals carry which allele. list the rea-
sons why this is unusual. Why can’t we usually
tell at a glance who carries which allele? - in Equations 6.1 and 6.2 we wrote the equation
for evolutionary change in the mean of a trait
(Δ–z) two different ways. using the definitions
of h^2 and β from the text, investigate the differ-
ences between these two equations. Can you
write the equation in a form that involves just
the quantities P, G, and β? Equations 6.1 and 6.2
seem to suggest that h^2 and G measure inheri-
tance, while β and S measure selection. Given
the ways you can rewrite these equations,
which of these are the best measures of inheri-
tance and selection? - There are many traits for which it seems natural
selection should favor an increase every gen-
eration, such as survival from birth to repro-
duction. in most cases, when we look for such
increases in natural populations we do not see
the predicted change. Make a list of all the rea-
sons we might not see a response to directional
selection on such a trait. include reasons sug-
gested by the material in this chapter, as well as
any other reasons you can think of.- When the technology for QTl mapping first
became available, researchers studying human
genetic diseases hoped to discover com-
mon alleles that cause increased risk for those
diseases. What would be the advantages to
studying the causes of diseases that are caused
by common, as opposed to rare, alleles? What
would be the advantages to treating diseases
that are caused by common alleles? - The results of QTl mapping studies for human
diseases tend to show that disease-causing
alleles are either rare or have very small effects
on risk. Knowing that this is true, discuss the
evolutionary forces that are most likely to be
responsible for this state of affairs. Does this
observation suggest something about the
evolutionary forces that maintain disease risk in
human populations?
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