Two competing hypotheses to account for the increase in the number of Hox genes from the last common ancestor of bilaterians to the last common ancestor of insects and vertebrates are: (1) a single duplication of the entire four-gene cluster, followed by the loss of one gene, and (2) three independent duplications of individual Hox genes. To prefer the first hypothesis on the basis of parsimony requires the assumption that ________.

Question

Quizplus · Accepted Answer

The first hypothesis is preferred on the basis of parsimony because it assumes a single duplication of the entire four-gene cluster followed by loss of one gene, which is simpler than the second hypothesis that assumes three independent duplications of individual Hox genes. However, this assumption requires the belief that the duplication of a cluster of four Hox genes is equally likely to the duplication of a single Hox gene.

Two Competing Hypotheses to Account for the Increase in the Number