Briefly describe the polygenic threshold theory.

Until very recently, the fitness of an individual getting familial retinoblastoma was zero, and if the frequency of babies with the inherited disease is 1/20000, what is the best estimate of the mutation rate of the wild type allele to the non-functional form?

Table 3. Common Single Gene Characteristics in Humans For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 Characteristic Tongue rolling (T). Not able to roll = t Free earlobes (E) attached earlobes = e Dimples (D). No dimples = d Widow's peak (W) straight hairline = w Freckles (F). No freckles = f Interlocking fingers (I). When you clasp your hands together, having the left thumb on top = 1 Phenotype Genotype

LO19 Analyze a cross and identify non-Mendelian pattern of inheritance in non-allelic genes (normal interaction vs epistasis) Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. What type of gene interaction does this represent? duplicate recessive epistasis normal non-allelic gene interaction Orecessive epistasis Odominant epistasis normal allelic gene interaction