Proposed Number of Hox Genes in Various Extant and Extinct Animals
$$\begin{array} { | c | c | c | c | }
\hline \begin{array} { c }
\text { Last } \
\text { Common } \
\text { Ancestor } \
\text { af Bilateria }
\end{array} & \begin{array} { c }
\text { Last Common } \
\text { Ancestor of Insects } \
\text { and Vertebrates }
\end{array} & \begin{array} { c }
\text { Ancestral } \
\text { Vertebrates }
\end{array} & \text { Mammals } \
\hline 4 & 7 & 14 & 3840 \
\hline
\end{array}$$
What conclusion can best be drawn from the data in the table?
A) Land animals have more Hox genes than do those that live in water.
B) All bilaterian phyla have had the same degree of expansion in their numbers of Hox genes.
C) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.
D) Extant insects all have seven Hox genes.

Question

Proposed Number of Hox Genes in Various Extant and Extinct Animals
$$\begin{array} { | c | c | c | c | } 
\hline \begin{array} { c } 
\text { Last } \
\text { Common } \
\text { Ancestor } \
\text { af Bilateria }
\end{array} & \begin{array} { c } 
\text { Last Common } \
\text { Ancestor of Insects } \
\text { and Vertebrates }
\end{array} & \begin{array} { c } 
\text { Ancestral } \
\text { Vertebrates }
\end{array} & \text { Mammals } \
\hline 4 & 7 & 14 & 3840 \
\hline
\end{array}$$
What conclusion can best be drawn from the data in the table?
A) Land animals have more Hox genes than do those that live in water.
B) All bilaterian phyla have had the same degree of expansion in their numbers of Hox genes.
C) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.
D) Extant insects all have seven Hox genes.

Quizplus · Accepted Answer

The number of Hox genes in mammals (3840) is much higher than what would be expected from just three duplications of the ancestral vertebrate Hox cluster (14), indicating additional expansions or duplications.