Andrew Suarez

Department of Entomology Department of Animal Biology

Ant Ecology and BehaviorBiological Invasions

www.life.uiuc.edu/suarez681/683 Morrill Hall

217-244-6631avsuarez@life.uiuc.edu

Why study biological invasions?

Unique opportunities for basic researchcommunity ecology

animal behaviorevolution

Consequencesthreaten biodiversity

costlywidespread

There are tens of thousands of introduced species in the USA

including: over 5000 plant species, 150 ant species…

Monster cane toad found in AustraliaWed 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 promote spread of other invaders.

Can modify habitat.

Can be predators, competitors, parasites, diseases.

Ultimately…displace native species

Homogenization

“Process in which a mixture is made uniform throughout”.

Biotic homogenization

Increasing similarity among areas in terms of species identity.

Displacement or replacement?

Habitat loss and modification coupled with thewidespread introduction of a few species leads

to homogenization.

Birds on islands (from Case 1996 Biol Con)

Alpha diversity = number of species locallyBeta diversity = turnover in species from site to siteGamma diversity = number of species regionally

Crooks 2002 Con. Biol.

House CatsOutdoor 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 antsHerbivores - leaf cutting antsSeed dispersers - harvester antsProtect plants - mutualistsTurnover soil, decomposersFood source

Black bars = invadedOpen bars = uninvaded

Phrynosoma coronatumDeclining throughout its range.A “sit and wait” ant specialist.

Shifts in body size: large ants lost

worker head width (mm)

% o

f ho

rned

liz

ard

diet

Argentine ant

Argentine ant

freq

uenc

y

worker head width (mm)

Pro

port

ion

initi

al w

eigh

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Hatchling horned lizards can not subsist on a diet of Argentine ants.

Hypotheses for the success of introduced species

Pre-adapted to disturbed environments

Increased competitive ability outcompete native species

Escape from natural enemies predators, parasites, disease

Allendorf and Lundquist2003 Conservation Biology

“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?

Hypotheses for the success of introduced species

Characteristics of invasive species

general diet and habitat requirementshigh abundancesmall body size

high reproductive potential (r-strategy)good competitorssocial / gregarious

high degree of plasticity generally?

Generalities would be nice!Make invasion biology a more predictive science.

Stages of invasion

(different characteristics may be important at different stages)

3. Spread

2. Establishment

1. Opportunity (transport)

What makes certain ecosystems vulnerable?

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

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

Disturbed habitats have more invaders

Diverse, undisturbed communities have few invaders

“Biotic resistance”

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/