Population geneticists study changes in the nature and amount of genetic variation in populations, the distribution of different genotypes, and how forces such as selection and drift act on genetic variation to bring about evolutionary change in populations and the formation of new species. From the explanation given in the chapter, what answers would you propose to the following fundamental questions?

How do we know the age of the last common ancestor shared by two species?

Key Concepts

Molecular Clock

The molecular clock is a method used to estimate the time of divergence between species by analyzing the rate of genetic mutations. By comparing DNA sequences, scientists can determine how many mutations have occurred since two species shared a common ancestor, allowing them to infer the approximate age of that ancestor.

Phylogenetics

Phylogenetics is the study of evolutionary relationships among biological entities, often using tree-like diagrams called phylogenetic trees. These trees illustrate how species are related through common ancestry, and the branching patterns can provide insights into the timing of divergences based on genetic data.

Fossil Record

The fossil record provides crucial evidence of the history of life on Earth, including the age of species and their ancestors. By dating fossils and understanding the geological layers in which they are found, scientists can estimate when certain species existed and how they relate to modern species, contributing to the understanding of common ancestry.