The figure shows the genealogies for two different genes. Which of the following is a reasonable explanation for the observed difference?
A) The gene in A is neutral. The gene in B experienced balancing selection.
B) The population size is smaller in A than B.
C) The gene in A is neutral. The gene in B experienced positive selection.
D) The mutation rate is lower in gene A than gene B.

Question

The figure shows the genealogies for two different genes. Which of the following is a reasonable explanation for the observed difference? 
A) The gene in A is neutral. The gene in B experienced balancing selection. 
B) The population size is smaller in A than B. 
C) The gene in A is neutral. The gene in B experienced positive selection. 
D) The mutation rate is lower in gene A than gene B.

Quizplus · Accepted Answer

A neutral gene would show a similar pattern of inheritance in both genealogies, whereas positive selection would lead to differences in the patterns of inheritance. The fact that the genealogy for gene B is more complex suggests that positive selection has favored certain variants over others, leading to multiple branches of inheritance. The population size or mutation rate may influence genetic diversity, but these factors would not typically explain such dramatic differences in the genealogies.

The Figure Shows the Genealogies for Two Different Genes