Imagine that, of three species, it is known that species 1 and 3 were separated 10 million years ago, based on geologic measurements. Genetic analysis at a neutral locus indicates that these species differ by 100 substitutions. If there are 10 substitutions separating species 1 and 2, approximately how long ago did these species diverge?
A) 0.1 million years ago
B) 1 million years ago
C) 10 million years ago
D) 100 million years ago

Question

Quizplus · Accepted Answer

Given that species 1 and 3, which were separated 10 million years ago, differ by 100 substitutions, we can infer a rate of 10 substitutions per million years. Since species 1 and 2 differ by 10 substitutions, they would have diverged approximately 1 million years ago, following the same rate of substitution.

Imagine That, of Three Species, It Is Known That Species