xohmymochax Posted March 1, 2010 Share Posted March 1, 2010 In certain salamanders, the sex of a genetic female can be altered, making her into a functional male; these salamanders are called sex-reversed males. When a sex-reversed male is mated with a normal female, approximately 2/3 of the offspring are female and 1/3 are male. How is sex determined in these salamanders? Explain the results of this cross. Link to comment Share on other sites More sharing options...
Radical Edward Posted March 7, 2010 Share Posted March 7, 2010 Salamanders determine sex using ZZ/ZW combinations - and in this system, ZZ are male and ZW are female. Now salamanders can reverse sex, and this can be induced by hormones, particularly steroids - no doubt there will be environmental triggers for this. if we have a sex-reversed (ZW) male and a normal (ZW) female, then we have the following combinations for the offspring (just do the punnet square) ZZ, ZW, ZW and WW. I would expect that much like you cannot have a y-y offspring in humans (but you can have XX, XY) because essential genes are missing on the y chromosome, the situation is the same with the ZW combination - WW is simply not viable, so the only offspring that are born are the ZZ (male) ZW and ZW (both female), explaining the 2/3 - 1/3 ratio. Link to comment Share on other sites More sharing options...
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