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
A)the duplication of a cluster of four Hox genes is equally as likely as the duplication of a single Hox gene.
B)there is an actual process by which individual genes can be duplicated.
C)genes can exist is spatial groupings called clusters.
D)clusters of genes can undergo disruption, with individual genes moving to different chromosomes during evolution.

Question

Quizplus · Accepted Answer

The first hypothesis is preferred based on the principle of parsimony, which states that the simplest explanation that requires the fewest assumptions is often the correct one. In this case, the duplication of an entire cluster followed by loss of one gene is a simpler explanation than three independent duplications of individual genes, which would require more assumptions about the likelihood and timing of each duplication event. The assumption that the duplication of a cluster of four Hox genes is equally as likely as the duplication of a single Hox gene supports the first hypothesis as the more parsimonious explanation.

Two Competing Hypotheses to Account for the Increase in the Number