Final answer:
Invasive species, like the zebra mussel and emerald ash borer, are non-native organisms that severely disrupt ecosystems, while non-invasive nonnative species coexist without causing significant harm. Both types are frequently introduced by human activities.
Step-by-step explanation:
Defining Invasive and Non-Invasive Nonnative Species
Invasive species are non-native organisms that can cause harm to native ecosystems. These species are characterized by their ability to spread rapidly and out-compete local species, thereby altering the natural habitats they invade. For example, the zebra mussel (Dreissena polymorpha) and the emerald ash borer (Agrilus planipennis) are known to have profoundly changed the ecosystems in the United States.
On the other hand, nonnative species that are not classified as invasive do not tend to cause significant harm to their new environments. They may exist alongside native species without disrupting the balance of the ecosystem. These non-invasive nonnative species may have been introduced intentionally, such as ornamental plants, or unintentionally, such as species transported in ship ballast water.
Whether invasive or not, nonnative species are a result of human actions, often due to globalization and international trade, which involves the movement of species beyond their natural geographic boundaries. The impact of these species can vary greatly, with invasive species often having considerable ecological, evolutionary, and economic consequences.