1. Exotic Species • Species invasions may profoundly affect ecosystems • Definition? • Criteria (Woods and Moriarty, 2001) • Human introduction • Direct vs. Indirect • Intention? • Is agency important? • Evolution • “Native” • How much does a species have to change? • Historical range • “Exotic” • How is a historical range determined/defined? • Degradation • How is “harm” defined? Some species harm & help • Community membership • What defines a “community”?

2. Exotic Species • Species invasions may affect ecosystems profoundly • Detrimental exotic species usually are • Superior competitors • Ex – European starling • Effective predators • Ex – Cane toad Distribution of cane toad in Australia Wikipedia

3. Exotic Species • Zebra mussel • Competitor in Great Lakes and elsewhere • Transported from Europe in ballast water • Fouling organism • Restricts movement of water through intake pipes • Colonizes boat hulls, pier pilings, buoys, etc. • Fouls other organisms (clams, mussels) • Filter feeder – removes larvae and particulate material • Outcompetes native shellfish species for food and space • Removes larvae from water

5. Exotic Species • Mongoose • Predator in Hawaii, Caribbean, etc. • Introduced to HI in 1883 to combat rats and snakes in sugar cane fields • Reproduce early and rapidly • Females can breed at 10 weeks, 2-3x a year, 2-3 young per litter • Prey on native birds, amphibians, reptiles

6. Nile perch – Lake Victoria Brown tree snake - Guam Argentine ants - California Caulerpa taxifolia - California

7. Exotic Species • May be especially detrimental to biodiversity and ecosystems when populations of keystone species are reduced or eliminated

8. Exotic Species • Are all exotic species bad? • What should we do about exotic species? • Ex:Eucalyptus in California