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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/