Answer
Phylogenies based on different genes can provide different branching patterns for multiple reasons: 1) Not all genes mutate at the same rate, so some genes might place two organisms in the same group while another gene might clearly differentiate them; 2) Some genes have been moved between taxa in the process of horizontal gene transfer, which would make some very different taxa seem closely related (for example, where prokaryotic genes were transferred to eukaryotes).
Work Step by Step
Review Concept 26.6 and pay special attention to horizontal gene transfer and how individual genes can move between taxa which are distantly related— for this reason, making a phylogeny with data from one gene could lead to great confusion. Also, review earlier material on differences in mutation rates among genes.