The relative lengths of the frog and mouse branches in the phylogenetic tree in Figure 26.13 indicate that:
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a. Frogs evolved before mice
b. Mice evolved before frogs
c. The homolog has evolved more rapidly in mice
d. The homolog has evolved more slowly in mice

Verified step by step guidance

1. Examine the phylogenetic tree provided in the image. Note that the tree represents evolutionary relationships among species, with branch lengths indicating the amount of genetic change or evolutionary divergence.
2. Identify the branches corresponding to the frog and mouse. Observe that the branch length for the mouse is longer than that of the frog.
3. Understand that longer branch lengths in a phylogenetic tree typically indicate a greater amount of genetic change or faster evolutionary divergence over time.
4. Interpret the relative branch lengths: the longer branch for the mouse suggests that the homolog (gene or trait being studied) has evolved more rapidly in mice compared to frogs.
5. Conclude that the correct answer is related to the rate of evolution of the homolog, specifically that the homolog has evolved more rapidly in mice.

Key Concepts

Phylogenetic Tree

A phylogenetic tree is a diagram that represents evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics. The branches indicate the lineage and the relative lengths can suggest the amount of evolutionary change or time elapsed.

Homologous Genes

Homologous genes are genes inherited from a common ancestor that may have similar sequences and functions across different species. The rate of evolution of these genes can vary, affecting the length of branches in a phylogenetic tree, which reflects the genetic divergence over time.

Evolutionary Rate

Evolutionary rate refers to the speed at which genetic changes accumulate in a species over time. In phylogenetic trees, longer branches typically indicate a faster rate of evolution, while shorter branches suggest slower evolutionary changes. This concept helps in interpreting the relative lengths of branches in the tree.