Only $35.99/year

AP Bio Evolution

Terms in this set (63)

From a study of soapberry bugs (Jadera haematoloma), a similar theme emerges that reflects the process of natural selection that Charles Darwin observed in the Galapagos finches. In order for soapberry bugs to feed, their "beak" length must match the depth of seeds in the balloon vine fruit. In central Florida, the native balloon vine has become rare and the Goldenrain tree, an introduced species from Asia, has become the main food source for soapberry bugs. Carroll and Boyd (1992) compared beak lengths of soapberry bug populations that fed on the native balloon vine in southern Florida with central Florida populations that fed on the Goldenrain tree, whose seeds are much closer to the fruit surface than the seeds of the plump balloon vine fruit. The researchers compared these data with the average beak length in museum specimens collected from the two areas before the Goldenrain tree was introduced (indicated by the red arrows). Which of the following suggestions is most likely true regarding the results of this study?

A) Soapberry bugs did not have to expend as much effort in probing for food on Goldenrain fruits, so beak length became shorter in the resulting offspring.

B) Soapberry bugs with shorter beaks had a selective advantage in Central Florida because they were better able to feed on Goldenrain fruits.

C) The results of this study are inconclusive because the researchers did not include an appropriate control group.

D) Random mutations probably occurred in the central Florida soapberry bug population that have nothing to do with food type as a selective pressure, but resulted in the predominance of shorter beak length due to reproductive isolation from the southern population.