| DQ 17.1 |
Fisher’s “Fundamental Theorem” quantifies the increase in mean fitness that is caused by selection on allele frequencies. What other factors influence the mean fitness of a population?
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| DQ 17.2 |
“Self-organization” describes the production of complex patterns by simple rules. What examples can you suggest? Explain the roles that natural selection and self-organization play in generating complex biological structures.
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| DQ 17.3 |
Complex functions—for example, novel drugs, electronic circuits, and computer programs—can be produced by rational design or by processes analogous to natural selection. What are the advantages and disadvantages of these two approaches?
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| DQ 17.4 |
A novel fungicide is introduced and widely applied to cereal crops. After five years, resistant genotypes of the fungal pathogen are detected at a frequency of about 1%; resistance is widely distributed across the pathogen’s range. Within two years, these have become so common that the fungicide becomes worthless. Resistance is shown to be due to a single-amino-acid change in the target protein; the pathogen has three generations per year. Show how this pattern can be explained by the basic features of natural selection.
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| DQ 17.5 |
There is enduring controversy over whether populations are typically trapped at local adaptive peaks or, instead, are usually evolving uphill on the adaptive landscape. What observations and experiments might distinguish these alternative views?
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| DQ 17.6 |
In Chapter 14, we saw that the phenotypic value of a quantitative trait can be written as the sum of a genotypic value and an environmental value. Typically, two different traits may be correlated because their environmental values are correlated and because their genotypic values are correlated. Explain the effects of (i) environmental correlations and (ii) genetic correlations on the response of a population to selection on multiple quantitative traits.
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| DQ 17.7 |
Figure 17.30 shows that although quantitative traits can change rapidly over short times (a few years, say), they change much more slowly over longer timescales of millions of years. What might explain this pattern?
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| DQ 17.8 |
Even when strong artificial selection is applied over many generations, additive genetic variance stays high, allowing a continued response to selection (see pp. 482–484). What might explain this observation and how might we distinguish alternative hypotheses?
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