Two species diverged from a common ancestor 2 mya based on fossil evidence. There are 10 amino acid differences in their hemoglobin molecules. We are interested in when 2 other related species diverged from a common ancestor. We don’t have any fossil evidence to help us but we do know that the 2 species have 20 amino acids different between them. According to the molecular clock, how many mya did these 2 species have a common ancestor?Group of answer choices1mya2 mya4 mya8 mya
Question
Two species diverged from a common ancestor 2 mya based on fossil evidence. There are 10 amino acid differences in their hemoglobin molecules. We are interested in when 2 other related species diverged from a common ancestor. We don’t have any fossil evidence to help us but we do know that the 2 species have 20 amino acids different between them. According to the molecular clock, how many mya did these 2 species have a common ancestor?Group of answer choices1mya2 mya4 mya8 mya
Solution
The molecular clock hypothesis suggests that DNA and protein sequences evolve at a rate that is relatively constant over time and among different lineages. In this case, we have a known divergence time of 2 million years ago (mya) for two species with a difference of 10 amino acids in their hemoglobin molecules.
This gives us a rate of 10 amino acid changes per 2 million years, or 5 amino acid changes per million years.
Now, we want to find out when two other related species diverged from a common ancestor. We know that these two species have 20 amino acids different between them.
Using the rate we calculated earlier (5 amino acid changes per million years), we can calculate the divergence time for these two species.
20 amino acid changes / 5 amino acid changes per million years = 4 million years ago
So, according to the molecular clock, these two species had a common ancestor 4 million years ago. Therefore, the answer is 4 mya.
Similar Questions
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