Bbr red slogan

(1) A female Drosophila melanogaster (BBRRRT) was crossed with a male homozygous wild-type (dominant) Drosophila melanogaster, and then the male F1(BBRRRT) was tested. Subtypic genes follow the law of free combination, so three pairs of genes are located on three pairs of homologous chromosomes respectively. Since Drosophila melanogaster * * has 4 pairs of homologous chromosomes (3 pairs of autosomes+1 sex chromosomes), and the progeny of the test has nothing to do with sex, the possibility that the short-legged gene is located on the sex chromosome (the stem of the gene that controls body color and wink) is ruled out, so the short-legged gene is most likely located on chromosome IV.

(2) According to the recessive traits and the hybrid ratio of their offspring, it can be inferred that there are four hybrid combinations between the two Drosophila species, namely BBTT TR× BBTT TR, BBTT TR× BBTT TR, BbRrTt×Bbrrtt and BbRrtt×BbrrTt. Among them, the hybridization types with different genotypes of male and female parents are BBRRTT× BBRRTT and BBRRTT× BBRRTT.

So the answer is:

( 1)Ⅳ

(2)4? BBR rrtt×BBR rrtt、BBR rrtt×BBR rrtt