Introduction to Genetic Analysis 22

Introduction to - First we note an average effect of environment in general the plants grew poorly at the medium elevation This is not true for

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Unformatted text preview: First, we note an average effect of environment: in general, the plants grew poorly at the medium elevation. This is not true for every genotype, however; the cutting of plant 4 grew best at the medium elevation. Second, we note that no genotype is unconditionally superior in growth to all others. Plant 1 showed the best growth at low and high elevations but showed the poorest growth at the medium elevation. Plant 6 showed the second- worst growth at low elevation and the second-best at high elevation. Once again, we see the complex relation between genotype and phenotype. Figure 1-22 graphs the norms of reaction derived from the results shown in Figure 1-21b. Each genotype has a different norm of re- action, and the norms cross one another; so we cannot identify either a “best” genotype or a “best” environment for Achillea growth. We have seen two different patterns of reaction norms. The difference between the wild-type and the other eye-size genotypes in Drosophila is such that the corresponding phenotypes show a consistent difference, regardless of the environment. Any fly of wild-type genotype has larger eyes than any fly of the other geno- types; so we could (imprecisely) speak of “large eye” and...
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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