In a famous experiment, Anders Möller studied the effect of tail length of male barn swallows on mating success. In one test group, he shortened the tails by clipping the tail feathers. In another test group, he lengthened the tails by adding feathers to the tails. He also included two control groups. In one control group, he did not manipulate the tail feathers. In another control group, he clipped the tail and then added the feathers back onto the tail, so they ended up the same length as the unclipped control tails. What is the dependent variable in this experiment? the tail length of male barn swallows the tail length of female barn swallowsThis experiment does not include a dependent variable.the mating success of the female barn swallows, which can be measured by the number of eggs, clutches, or offspring the mating success of the male barn swallows, which can be measured by the number of eggs, clutches, or offspring