An individual heterozygous for four genes, AaBbCcDd, is testcrossed to aabbccdd, and 1000 progeny are classified by the gametic contribution of the heterozygous parent as follows: aBCD 42, Abcd 43, ABCd 140, abcD 145, aBcD 6, AbCd 9, ABcd 305, abCD 310.

(a) Describe the specific linkage arrangement, if any, for these four genes.

(b) If two pure breeding lines were crossed to produce the heterozygous individual, what were their genotypes?

(c) Draw a linkage map for any linked genes, showing the order and the distance in map units.

(d) Calculate interference value, if appropriate.