Are horses native species immigrant indicator or keystone species?

Horses are not native to North America. They are considered immigrant indicator species, meaning their presence indicates the arrival of humans. Here's why:

* Origin: Horses originated in North America but went extinct there around 10,000 years ago.

* Reintroduction: Horses were reintroduced to North America by European colonists in the 15th century.

* Impact: The introduction of horses significantly altered the landscape and ecosystems of North America, impacting native species.

Keystone species are defined by their critical role in maintaining the structure and function of an ecosystem. While horses can have an impact on the ecosystem, they don't fulfill the criteria to be considered keystone species.

In summary:

* Native: No

* Immigrant Indicator: Yes

* Keystone Species: No