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Andrew Suarez
Department of Entomology
Department of Animal Biology
Ant Ecology and Behavior
Biological Invasions
www.life.uiuc.edu/suarez
681/683 Morrill Hall
217-244-6631
[email protected]
Why study biological invasions?
Consequences
threaten biodiversity
costly
widespread
Unique opportunities for basic research
community ecology
animal behavior
evolution
There are tens of thousands of introduced
species in the USA
including: over 5000 plant species, 150
ant species…
Monster cane toad found in Australia
Wed Mar 28, 2007
SYDNEY (Reuters) - A huge cane toad the size of a small
dog has been captured in the Australian tropical city of
Darwin, startling environmentalists who are fighting to stop
the poisonous amphibians spread across the country.
"It's a monster toad," said Paul Cowdy from FrogWatch
which captured the cane toad on Monday night. "We've
never seen a cane toad this big," he said on Tuesday. "It's
a male and normally females are bigger."
Phillips et al. 20006, Phillips et al. 2008
How do they impact native species?
Can be predators, competitors, parasites, diseases.
Can modify habitat.
Can promote spread of other invaders.
Ultimately…displace native species
Displacement or replacement?
Homogenization
“Process in which a mixture is made uniform throughout”.
Biotic homogenization
Increasing similarity among areas in terms of species identity.
Habitat loss and modification coupled with the
widespread introduction of a few species leads
to homogenization.
Alpha diversity = number of species locally
Beta diversity = turnover in species from site to site
Gamma diversity = number of species regionally
Birds on islands (from Case 1996 Biol Con)
Crooks 2002 Con. Biol.
House Cats
Outdoor cats and feral cats and recreational
hunters. Can cause declines in populations of
native mammals, birds and lizards.
Complex effort to rid San Nicolas
Island of cats declared a success.
Feb 26, 2012.
The six-agency project cost more than $3 million and entailed
18 months of trapping on the Navy-owned island off Southern
California. The cats killed cormorants, gulls and a threatened
lizard.
Ant invaders in North America
Over 50 species introduced to Hawaii
At least 50 other species established on
continental U.S.
On the mainland two widespread species:
Red imported fire ant
Argentine ant
The red imported fire ant
Why worry about introduced ants?
Can have ecosystem level effects.
Argentine ant
Ants are important parts of
nearly all ecosystems
Top predators - army ants
Herbivores - leaf cutting ants
Seed dispersers - harvester ants
Protect plants - mutualists
Turnover soil, decomposers
Food source
Black bars = invaded
Open bars = uninvaded
Phrynosoma coronatum
Declining throughout its range.
A “sit and wait” ant specialist.
% of horned lizard diet
Argentine
ant
worker head width (mm)
Shifts in body size: large ants lost
Argentine
ant
worker head width (mm)
native ants
arthropod community
Argentine ants
1.4
1.2
1.0
0.8
week
0
week
1
week
2
week
3
week
4
Hatchling horned lizards can not subsist on a diet of Argentine ants.
Hypotheses for the success of introduced species
Escape from natural enemies
predators, parasites, disease
Increased competitive ability
outcompete native species
Pre-adapted to disturbed environments
Hypotheses for the success of introduced species
“Paradox of Invasion”
1. If population bottlenecks are harmful, why are
invasive species that have gone through a genetic
bottleneck so successful?
2. If local adaptation is important, why are introduced
species so successful at displacing native species?
Allendorf and Lundquist
2003 Conservation Biology
Characteristics of invasive species
general diet and habitat requirements
high abundance
small body size
high reproductive potential (r-strategy)
good competitors
social / gregarious
high degree of plasticity generally?
Generalities would be nice!
Make invasion biology a more predictive science.
Stages of invasion
1. Opportunity (transport)
2. Establishment
3. Spread
(different characteristics may be important at different stages)
What makes certain ecosystems vulnerable?
Diverse, undisturbed communities have few invaders
“Biotic resistance”
Disturbed habitats have more invaders
Human residential areas: many European species that are
commensal with humans
Islands: little history with competitors, predators,
parasites, or diseases
Priorities for future research:
Comparisons of native & introduced populations
(determining native range)
More experimental, large-scale & long-term studies
Better estimates of density & biomass
Prevention & control
Prevention
Education is key
Research is still needed - generalities?
Monitoring programs - early detection
Prevent establishment - quarantine
Increased communication among agencies
Increase regulations
http://www.invasivespeciesinfo.gov/