Biology Chapter 3

1. Biology Chapter 3 Notes #3

2. Native vs. Introduced • Native species are plants and animals that naturally inhabit an area. • Introduced species are species which are introduced into an ecosystem and usually either benefit or harmless to the ecosystem • Also called foreign species • Invasive species are organisms that can take over the habitat of native species or invade their bodies.

3. Invasive species • Because of climate change and increased world travel and trade there is more movement of species into new ecosystems. • The number of invasive species in ecosystems is increasing • This can lead to loss of biodiversity • Characterized by • High reproductive rates • Being aggressive competitors • Lacking natural predators in new habitat

4. Impact of Introduced Invasive Species • Invasive species can exploite niches and affect native species through • Competition • Predation • Disease • Parasitism • Habitat alteration

5. Competition • Invasive species compete against native species for: • Food • Habitat • Unbalance natural resource sharing • Example: burweed on Saltspring Island • From South America • Competes with 4 natural species • Spiny tips

6. Predation • Invasive species may act as a predator to native species in the ecosystem • Prey have not adapted to that predator (escape/fight) • Example: Yellow crazy ants • From West Africa • Introduced to Christmas Island Austraila • Build supercolonies (500 football fields) • Prey on many things including red crabs (keystone species)

7. Disease and Parasitism • Invasive species like viruses and bacteria and other organisms • Weaken immune systems in native species • Other species can outcompete weak species • Example: Parasitic Sea Lamprey • From Atlantic Ocean • Moved into Great Lakes • Attach to fish and suck out body fluids

8. Habitat alteration • Invasive species can change ecosystems • Native species unable to survive • Examples • Light levels • Oxygen levels in water • Soil chemistry • Increased erosion • Unbalance nutrient cycles and energy flow • Example: Wild boars • Damage systems by rooting, wallowing, and spreading weeds • Omnivores: eat birds, reptiles, frogs, soil organisms, fruit, seeds, bulbs

9. Examples of Invasive Species • Eurasian milfoil • Norway rat • American bullfrog • European starling • Group Activity • 8 groups • Each group looks at one invasive species example • Find out: • Where it is invading • How it got there • What it does in the system • How is it being combated • 2 groups get together compare notes, then share with class

10. Eurasian milfoil

11. Norway rat

12. American bullfrog

13. European starling