Why do invasive species pose such a threat? (Site 1).

Invasive species are harmful to wildlife in many ways. When a new offensive species is introduced into an ecosystem, it may not have natural enemies or controls. It grows rapidly, spreads, and can occupy an area.

Invasive species are alien species (disease, parasites, plants, animals) that have begun to expand or expand from the first alien species and can be harmful to the environment and economy. Or the environment for human health.  

Invasive species can make their natural habitat unsuitable for native species by altering their structure and composition. This can mean changes in light conditions, changes in soil chemistry, or increased soil erosion. They can also upset the balance of nutrient circulation, pollination, and energy flow.

Thus it concluded the fact that invasive species are dangerous as it degrades, changing habitats.

To know more about invasive species refer to the link;

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.