```
Common Ancestor
|
V
Genus 1
|
V
Species A Species B
| |
V V
Variety 1 Variety 2 Variety 3
```
In this chart, the common ancestor is the base from which all other species and varieties evolved. Genus 1 is a descendant of the common ancestor and is in turn the ancestor of Species A and Species B. Species A and Species B are sister species, meaning they share a common ancestor that is no longer extant. Variety 1, Variety 2, and Variety 3 are all descendants of Species B and are therefore more closely related to each other than they are to Species A.