In Drosophila , the alleles for cubitus interruptus veins ( ci ) and sparkling eyes ( spa ) are 3.0 map units apart on chromosome four. A homozygous cubitus fly is crossed with a homozygous sparkling fly, yielding doubly-heterozygous F 1 . F 1 females are then crossed to doubly-homozygous recessive cubitus , sparkling males to give F 2 . How many offspring with the phenotype ci, spa do you expect to recover? Assume that you have 1000 total F 2 flies. .