3.3 How Introduced Species Affect Ecosystems

Question 1

What are native species?

Answer 1

Plants and animals that naturally inhabit an area

Question 2

What are foreign/introduced species?

Answer 2

Organisms that people intentionally or accidentally have introduced into regions where they didn’t previously exist; many foreign species are harmless or may even be beneficial

Question 3

What are invasive species? Give an example.

Answer 3

• organisms that can take over the habitat of native species or invade their bodies, weakening their immune system
• eg. purple loosestrife was brought to North America several 100 years ago and has destroyed wetlands because it quickly reproduces and chokes out other plants

Question 4

What are some introduced species in BC? (4)

Answer 4

• Eurasian Milfoil
• Norway Rat
• American Bullfrog
• European Starling

Question 5

The rapid spread of introduced invasive species is a major cause of _________.

Answer 5

global diversity loss

Question 6

What are some traits (behaviours? or advantages?) invasive species have? (3)

Answer 6

• have high reproductive rates
• are aggressive competitors
• lack natural predators in new habitats

Question 7

Invasive species often take advantage of their new habitat, resulting in proliferation. What is proliferation?

Answer 7

to grow or multiply by rapidly producing new tissues, cells, or offspring

Question 8

How can foreign species affects native species? (4)

Answer 8

• competition
• predation
• disease and parasitism
• habitat alterations

Question 9

What happens during competition? Give an example.

Answer 9

• native species have and established balance in the competition for and food and habitat, and the invasive species disturbs this balance
• The European starling outcompetes BC’s western blue bird for nesting habitat

Question 10

What happens during predation? Give an example.

Answer 10

• if the invasive species is a predator, it may have a huge advantage since the native species may have no methods to survive against it
• eg. Norway Rats prey on BC’s round-nesting birds

Question 11

What happens during disease and parasitism?

Answer 11

• by weakening certain species, a micro-organism invading an ecosystem can drastically alter the entire ecosystem and the niches within them

Question 12

What happens during habitat alteration? Give an example.

Answer 12

• some invasive species change the physical structure of the ecosystem by digging, burrowing, blocking sunlight, or changing the ecosystem’s chemistry
• eg. Eurasian milfoil form wide, dense mats at lake surfaces, cutting off sunlight to organisms below, it grows from plant fragments often spread by boats