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To humor a predominant Western culture bias of how a human couple should look, and because of the statistic that men are physically bigger (at least taller/broader-shouldered) than women, I designed a female fly with small wings (M) and a male wild type (+). I hypothesized that this physical dynamic would be true in the fly world as well, because I could start with the assumption that the wild-type is the dominant trait.

I.         The first generation (H1) yielded results contrary to my hypothesis:

527 female +                      459 male M
(wild type)                          (mini-wings)
                     1.148 :    1

This surprised me due to my human bias and my assumption that + was dominant. Typically, when a wildtype fly is crossed with a fly that has a single non-wildtype trait, the H1 generation shows no phenotypical trace of the non-wildtype trait. In this case, not only did the non- wildtype trait show up—it showed up in the opposite gender of its parent who carried it (H1 males only had small wings, and H1 females only were +).

I changed my hypothesis to account for this when I remembered that the case with species other than humans sometimes ends up with the female larger than the male: female snakes are bigger than male snakes, and queen bees/ants are bigger than their male counterparts, for instance.

I continued to breed. At H4, there were males with +, but still more males with M and no females at all with M. By H6, the M had gone away completely, and stayed that way until I stopped breeding at H13.

II.      What was most interesting about this was how dominance played out between males and females. I did the experiment again but started the male with M (mini-wings) and the female as + to see if the trait really was true to gender, and didn’t just switch which gender got which trait in the parents.

In this case, females never carried the M trait, and males held onto it until H9 (as opposed to H6 in I.). At H9, there were only wildtype males and females.

My conclusion is that “small wings” is a trait only dominant in male flies, but then only present in male flies for a few generations (the number of + males was consistently only a little big higher than the number of M males) until it completely drops out.

 

I also tried a three-part experiment to see what would dominate between two seemingly handicapping traits: vestigial wings (VG) and incomplete wing veins (IR). A.) I mated a female with incomplete veins and a male with vestigial wings. I gathered data from that for 10 generations. B.) Then i mated a female with both RI and VG and a Male +, tested for 13 generations. C.) Then I flipped it and mated at female + and a male with RI and VG. I wanted to see what the differences would be/if there would be differences in which non-dominant/non-wildtype traits stuck to which gender depending on which initial parent had what.

 

Results:

A.  To be contin