Question

I need help with a question (it's kind of urgent):

A team of scientists is studying a mitochondrial DNA sequence shared by two species, and they determine that the DNA has a constant mutation rate. The DNA sequences of the two species are shown below.

Species A: GTAGGCATTCGAT
Species B: GTAGGCATACGTT

Based on this information, which of the following best explains the difference in the DNA sequence between the two species?

Both differ by three mutations which means they have a close ancestor.
The constant rate of the mutation means that less time has passed.
Fewer differences in DNA lead to more mutations as time passes.
Species A and B are under pressure due to natural selection.

Answer 1

Based on the information provided, the option that best explains the difference in the DNA sequence between the two species is:

"Both differ by three mutations which means they have a close ancestor."

The fact that the two species have a mitochondrial DNA sequence with the same constant mutation rate and differ by only three mutations suggests that they have a relatively recent common ancestor. Over time, mutations accumulate in DNA sequences, so the fewer differences in DNA sequences between two species, the more recently they shared a common ancestor. Therefore, it is likely that species A and B are closely related and diverged from a common ancestor relatively recently. This is supported by the fact that they have a similar mitochondrial DNA sequence, which is inherited maternally and can provide information about evolutionary relationships.