Give an example of the characteristics being used to determine how close two species are in evolutionary terms.
Homologous organs is the characteristic used to determine how close two species are in evolutionary terms.
Homologous organs are the organs that have the same structural plan and origin but have different functions.
Example: Wings of birds and forelimbs of humans perform different functions but they have similar skeletal structure because they have the same origin.
As the above example suggests, the basic structure of both are the same but they were modified to perform different functions .
This is because they have evolved from a common ancestor and thus helps us in determining the closeness between two species in evolutionary terms.