Genetics Cross Problem

[scinerd]

Hey guys, I'm having trouble working out this genetic problem (it is a three part problem) :

 

The drosophilla mitant traits vermillion eye (ver), wings absent (wab) and crowssveinless (cvl) represent vermillion eye colour, no wings and no crossveins in the wing, respectively. A male with vermillion eyes and wings absent was crossed to true breeding crossveinless females. Of the F1 progeny, half of them had the wings absent phenotype.

The F1 females showing this wings absent phenotype were then crossed to a true breeding individual showing the vermillion eyes and crossveinless phenotype. The phenotype from a total of 1000 progeny were as follows:

 

wildtype 6

crossveinless 388

wings absent 102

vermillion eyes 68

vermillion eyes, corssveinless 34

vermillion eyes, wings absent 402

 

What is the order of the three genes (if they are linked) and their distance from one another (i.e. distance from ver to wab, from wab to cvl and from cvl to ver)?

 

I know that crossveinless and vermillion eyes, wings absent are parental type and the wildtype is the double recombinant, so I sort of worked out from there that cvl is the middle gene (if I'm not wrong that is). I am assuming the reciprocal class of the double recombinant (triple mutant) is not seen in the offspring because it is lethal. Not sure if why the other single recombinant class is missing and also no clue to where to start to find the distance between the genes.

SOMEONE PLEASE HELP ME!!! >.<

[scienceunraveled]

What you are missing is a cvl+ and wab+ in the F2 progeny, I would assume this combination is lethal as well as the double recombinant. To find the distance between the genes then you need to determine the parentals from the F1 progeny and find which had the least amount of crossover so they the first and third. I assumed the females from the F1 were 1/2 wab because they were (ver+,cvl-,wab+/ver-,cvl+,wab-) I couldn't assume x-linked because of the amount of F1 progeny with wab, too high for a single cross over event. So I assumed it was autosomal.