20Chapter 1 •Genetics and the Organismof ﬂies raised at lower temperatures. These norms of re-action indicate that the relation between genotype andphenotype is complex rather than simple.MESSAGEA single genotype may produce differentphenotypes, depending on the environment in whichorganisms 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 eyehas 800 or 1000 facets. On the other hand, the knowl-edge that a fruit ﬂy’s eye has 170 facets does not tell uswhether its genotype is ultrabaror infrabar.We cannoteven make a general statement about the effect of tem-perature on eye size in Drosophila,because the effect isopposite in two different genotypes. We see from Figure1-20 that some genotypes do differ unambiguously inphenotype, no matter what the environment: any wild-type ﬂy has larger eyes than any ultrabaror infrabarﬂy.
This is the end of the preview. Sign up
access the rest of the document.
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.