NRES 348 — Lec 15: Invasive Species

What is an invasive species?

A non-native species whose introduction causes or is likely to cause environmental, economic, or human health harm.

What is the difference between exotic & invasive species?

• Exotic = a species living outside its native range

• Invasive = a non-native species that causes or threatens harm. Not all exotic species become invasive.

What are the 4 stages of biological invasion?

Transport → Establishment → Spread → Impact

Each stage has barriers, & management becomes more difficult & expensive as an invasion progresses.

What is the Tens Rule?

A general rule suggesting that about 10% of introduced exotic plants escape into the wild, 10% of those become naturalized, & 10% of those become invasive. This equals approximately 1 in 1,000 introductions.

What is biotic resistance?

When native species, including competitors, predators, parasites, & pathogens, make it harder for a non-native species to establish.

What is propagule pressure?

The number of individuals introduced & the frequency of introductions. Higher propagule pressure increases the likelihood of successful establishment.

What is the enemy release hypothesis?

The idea that invasive species can establish successfully because they escape natural enemies, such as predators, parasites, & herbivores, in their new environment.

How do invasive species spread?

Through population growth & dispersal. Long-distance dispersal is especially important because individuals can establish new satellite populations.

What are the main impacts of invasive species?

They can harm native populations, biodiversity, ecosystems, human health, economic activities, & ecosystem services.

What are the 3 main approaches to invasive species management?

• Prevention = stop species from entering

• Eradication = completely eliminate an introduced population.

• Control = reduce or manage an established invasive population.