Final answer:
Invasive species disrupt ecosystems by out-competing and predating native species, introducing diseases, and causing ecological and economic harm. They can spread through human transport, trade, ecological changes, and directly through predation and competition. Examples in the U.S. include the purple loosestrife, zebra mussel, emerald ash borer, and European starling.
Step-by-step explanation:
Invasive species are non-native organisms that cause disruption when they are introduced to ecosystems outside their native range. They are detrimental to local environments because they can out-compete native species, introduce diseases, and cause ecological and economic harm. Invasive species can spread through a variety of ways, four of which include:
- Human transport: An important pathway where species are moved intentionally or unintentionally by human activities.
- Trade: Movement of organisms for commercial purposes can lead to the introduction of invasive species to new areas.
- Ecological changes: Modifications in the environment, such as those brought by climate change, can enable invasive species to establish and spread.
- Predation and competition: Invasive species can disrupt food webs and directly compete with native organisms for resources.
In the United States, examples of invasive species include the purple loosestrife, zebra mussel, emerald ash borer, and the European starling. They can dramatically modify entire ecosystems, which has vast consequences for biodiversity and ecosystem functioning. In terms of economic impact, invasive species can also become agricultural pests or weeds, leading to significant losses.