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Anna Chiles, Jennifer Pierre

Biology 103

Professor Grobstein

Lab 8 November 18, 2009

Hybrid and Dihybrid Crosses with Fruit Flies

                In today’s lab, we simulated the mating of fruit flies on FlyLab to examine the presence of certain traits. In facilitating the mating of two parental fruit flies of differing traits (i.e. a Wildtype female with an Aristopedic male), we were able to produce hybrid and dihybrid crosses to determine the genotypic and phenotypic make-ups of their first generation and second generation offspring. We were able to give credit to Mendel’s hypothesis that genes come in pairs and that there is a difference between genotypes and phenotypes. We found one example, however, that put into question Mendel’s theory and also the independence of traits. Below is a diagram of our findings from mating a Sable-colored female fruit fly with a Wildtype male.

                Female                                                                                                 Male

Noticing that this was different than our other results, we decided to run this cross again, this time using a Wildtype female and a Sable-colored male. Below are our findings.

                Female                                                                                                                 Male

There is obviously a discrepancy between our findings and the findings of Mendel. We have concluded that this discrepancy must be related to gender/sex of the fruit fly. That we produced different results when we switched the traits from female to male suggests that body color, specifically Sable, is a sex-linked trait and, thus, does not apply to Mendel’s hypothesis. One explanation for this, borrowed from our lab discussion today, could be that genes are located in clusters on chromosomes and that they are not independent.