VISUAL SKILLS The relative lengths of the frog and mouse branches in the phylogenetic tree in Figure 26.13 indicate that 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.

Key Concepts

Phylogenetic Trees

Phylogenetic trees are diagrams that represent the evolutionary relationships among various biological species based on their genetic or physical characteristics. The branches of the tree indicate how closely related different species are, with the length of the branches often reflecting the amount of evolutionary change or time since divergence.

Homologous Structures

Homologous structures are anatomical features in different species that share a common ancestry, even if their functions may differ. The study of homologs helps scientists understand evolutionary relationships and the processes of adaptation and divergence among species.

Evolutionary Rates

Evolutionary rates refer to the speed at which genetic changes occur in a lineage over time. These rates can vary significantly between species, influenced by factors such as environmental pressures and reproductive strategies, and can be inferred from the lengths of branches in a phylogenetic tree, indicating how quickly certain traits have evolved.