Andrew Suarez Department of Entomology Department of Animal Biology Ant Ecology and Behavior Biological Invasions 681/683 Morrill Hall

Why study biological invasions? Unique opportunities for basic research community ecology animal behavior evolution Consequences threaten biodiversity costly widespread

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 , 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 the widespread introduction of a few species leads to homogenization.

Birds on islands (from Case 1996 Biol Con) Alpha diversity = number of species locally Beta diversity = turnover in species from site to site Gamma diversity = number of species regionally

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, 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.

Shifts in body size: large ants lost worker head width (mm) % of horned lizard diet Argentine ant Argentine ant frequency worker head width (mm)

Proportion initial weight 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 Lundquist 2003 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 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 (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