preceding generation. For example we might establish one population from the cross of the two shortest plants and another population from the cross of the two tallest corn plants in the preceding example. Then, in each successive generation, the “short” population and the “tall” population would be bred from the most extreme individuals in each. If, after repeated generations of selection, the populations diverge, then the divergent populations must differ genetically at one or more loci in±uencing the character. • Heritability studies, in which the variation in the progeny of crosses is analyzed statistically to estimate the proportion of the variation in the original population that is a consequence of genetic differences and the proportion that is a consequence of environmental differences. • Quantitative trait locus (QTL) studies, which associate phenotypic differences with alleles of a marker gene of known chromosomal location. Such an association with the marker gene reveals the
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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.