Invasive Species

What are native species?

Native species are those that normally live and thrive in a particular community. They occupy specific habitats and have specific niches in their native environment.

They have natural predators that help to keep their populations in check.

Buffalo Grass Scissor tailed Flycatcher Black Bear

Definition

• Invasive species-are plants, animals, or pathogens that are non-native to the ecosystem under consideration and whose introduction causes or is likely to cause harm.

How did they get here?

• Some introduced deliberately:

• naturalization societies

• Shakespeare fans

• game animals

• domestic animals

• Some accidental:

• ballasts of ships

• unprocessed wood

• fruit shipments

• by-pass natural barriers

What makes certain ecosystems more vulnerable?

Islands: little history with competitors, predators, parasites, or diseases

Human residential areas: many European species that are commensal with humans

Disturbed habitats: full of invaders

Diverse, undisturbed communities have few invaders

Common characteristics of invasive species

Invasive species in general:• Have few natural

predators, competitors, parasites or diseases

• Have high reproductive rates

• Are long-lived• Are generalists • Are pioneer species

Characteristics that make Zebra mussels a good invader include its ability to tolerate a wide-

range of environments, and high reproduction rate; female mussels release up to 100,000 eggs ability to tolerate a wide-range of environments

year.

Discussion: how would these characteristics enable a species to become invasive?

What traits are common to invasive plant species

• Self-compatible• Flower early• Produces abundant seed• Disperse seed widely• Grow rapidly• Spread asexually• Strong competitorsCharacteristics that make tree-of-heaven a good

invader include its ability to flower early (within 2 years), ability to spread asexually, and fast

growth rate.

Impacts of invasive speciesEconomic impacts:

Invasive species are responsible for tremendous economic losses through loss in forest and agricultural productivity, spread of diseases that impact humans,

among other impacts.

European starlings, Sturnus vulgaris, spread diseases to wildlife, livestock, and humans,

damage agricultural crops, and displace native birds. Their damage to agricultural

crops is estimated at $800 million annually.

•First successful introduction was 60 European starlings released in Central Park, NY. in 1890, by fans of Shakespeare

European Starling

–competes with bluebirds, woodpeckers

Do we have any?

• Zebra mussel • What: Mollusk• How: Caspian Sea region of Asia; accidentally released into Lake St. Clair in

1988 in ship ballast water • How Bad: Voracious filter feeders that out-compete native animals; fouls

boats & clogs intake pipes at power plants and municipal water sources

Do we have any?

• Dutch Elm Disease• What: Fungus• How: Asia; one strain of the disease arrived in the 1930s in Cleveland, OH on

infected elm logs from Europe; a more virulent strain arrived in 1940s • How Bad: Elms were once the nation’s most popular urban street tree, have

now largely disappeared from both urban and forested landscapes. It is estimated that “Dutch” elm disease has killed over 100 million trees.

Do we have any?

• Fire Ant• What: Insect• How: South America; accidentally introduced to Alabama in 1930s • How Bad: Aggressive, multiple biter with painful venom and chance of allergy;

may also damage fruits, berries and young crops; also damage electric boxes; ant mounds are a hazard to farm equipment.

Do we have any?

• Musk Thistle• What: Weed• How: Europe and Eurasia; Introduced to OK in 1944 possibly in contaminated

seed• How Bad: Hardy weed that outcompetes native vegetation

HUGE PROBLEMS

• https://www.youtube.com/watch?v=rPeg1tbBt0A (Asian Carp)• https://www.youtube.com/watch?v=Gtqb41CjQfc (Zebra Mussels)