Methods in Anopheles Research - MR4

Chapter 2 : Anopheles Biology Laboratory and Culture2.5 Basic Anopheles Mendelian GeneticsPage 6 of 8Inheritance of two linked autosomal genesProblem 3: In this case, we consider two loci that are linked. We will use the Punnett Square to describethe pattern using collarless and Dieldrin resistance (Rdl) (Davidson 1956; Davidson and Hamon 1962)assuming 15% recombination. Rdl R is fully dominant. The recombinant gametes of either complementaryclass will be formed at equal rates. This example is set up as a typical testcross in which a doubleheterozygousfemale is crossed to a homozygous male that has the recessive alleles for both markers.Female GametesNon-recombinantRecombinant3a. Rdl R c+proportion =3b. Rdl S cproportion =3c. Rdl R cproportion =3d. Rdl S c+proportion =………………………………………………………………Male Gametes3e. Rdl S c proportion =………………3f. Rdl S c proportion =………………3g = …………. 3h = …………. 3i = …………. 3j = ………….3k = …………. 3l = …………. 3m = ………. 3n = ………….Determine the genotypic frequencies.3o. Rdl R c+ / Rdl S c __________ This is one 'parental' class3p. Rdl S c / Rdl S c __________ This is the other 'parental' class3q. Rdl R c / Rdl S c __________ This is one 'recombinant' class3r. Rdl S c+ / Rdl S c __________ This is the other 'recombinant' classDetermine the phenotypic frequencies3s. Rdl R c+ ____________ parental3t. Rdl S c ____________ parental3u. Rdl R c ____________ recombinant3v. Rdl S c+ ____________ recombinantNotice that in a testcross, the genotypic and phenotypic frequencies are identical. The frequency of allgenotypes can be determined conclusively. In contrast, a backcross to one of the parents may or may notbe a testcross.