Biotic Resistanc

eWhat can stop

invasive species?

Liz Schultheis

April 21, 2011

Do you know of any invasive species?

Why do some invaders succeed?

• Open habitat – places to grow• Available food/resources• Can grow better than native species• Nothing eats them! No enemies

Why do some invaders fail?

• Diversity – lots of competition – no space or resources left

• Enemies – diseases, predators, herbivores

Native Blue CrabLikes soft sandy areasLives in shallow water

Prefers ocean water that’s not too salty

Invasive Green Crab

Introduced from EuropeLikes the same areas that the Blue

Crab likes

Catherine E. deRivera & others 2005

Native Blue Crab Range

Invasive Green Crab

Range

SOUTH NORTH

LOCATIONS

#

Blu

e C

rab

s

#

Gre

en

C

rabs

SOUTH

NORTH

Winner!

N N N N N N N N N N

N N N N N N N N N N

N N N N N N N N N N

N N N N N N N N N N

N N N N N N N N N N

N = invader resource

N N N N N N N N N N

N N N N N N N N N N

N N N N N N N N N N

N N N N N N N N N N

N N N N N N N N N N P P P PP P P P P P P P P PP P P P P P P P P PP P P P P P P P P PP P P P P P P P P PP P P P P P

N = invader resource

P = native species resource

N N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P P

Div

ersi

ty =

1N = invader resource

P = native species resource

N N N N N N P P P P

N N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PD

iver

sity

= 3

P P P N N

N = invader resource

P = native species resource

N N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P P

Div

ersi

ty =

3, F

ertil

ized

N = invader resource

P = native species resource

N N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PN N N N N N N N N N P P P PP P P P P PD

iver

sity

= 3

, Dis

turb

ance N =

invader resource

P = native species resource