Introduction to Genetic Analysis 21

Introduction to Genetic Analysis 21 - 44200_01_p1-26 3/2/04...

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20 Chapter 1 Genetics and the Organism of flies raised at lower temperatures. These norms of re- action indicate that the relation between genotype and phenotype is complex rather than simple. MESSAGE A single genotype may produce different phenotypes, depending on the environment in which organisms develop. The same phenotype may be produced by different genotypes, depending on the environment. If we know that a fruit fly has the wild-type genotype, this information alone does not tell us whether its eye has 800 or 1000 facets. On the other hand, the knowl- edge that a fruit fly’s eye has 170 facets does not tell us whether its genotype is ultrabar or infrabar. We cannot even make a general statement about the effect of tem- perature on eye size in Drosophila, because the effect is opposite in two different genotypes. We see from Figure 1-20 that some genotypes do differ unambiguously in phenotype, no matter what the environment: any wild- type fly has larger eyes than any ultrabar or infrabar fly.
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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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