Monophyly

Monophyly is like having a family tree, but instead of people, it's for animals or plants. Just like you have grandparents, parents, and siblings, animals and plants have ancestors too! Monophyly means that all the animals or plants in a group share the same great-great-great-grandparent, or very distant ancestor.

Let's take dogs as an example. All dogs, from Chihuahuas to Great Danes, share a common ancestor, which was a wolf. This common ancestor is the great-great-grandparent of all dogs. This means that the group of dogs is monophyletic. Each dog breed, like Labradors, bulldogs or Shih Tzus, has a different family tree, but they all have a wolf as the ancestor at some point in their family history.

To be monophyletic, all the animals or plants in a group must have a common ancestor and all of its descendants should be included in the group. This means that if an animal or plant is left out, it can't be part of the group. For example, let's say we have a group of animals called "big cats". All the big cats, like lions, tigers and leopards share a common ancestor. But if we include other animals like cheetahs or jaguars, we break the monophyly of the group because these animals don't share the same common ancestor as the rest of the big cats.

So remember, monophyly just means that all the animals or plants in a group are related and share the same very distant ancestor. It's like having a large family where everyone is related to everyone else in some way!