I Exotic Species Species invasions may profoundly affect

I. Exotic Species • • Species invasions may profoundly affect ecosystems Definition? • Criteria (Woods and Moriarty, 2001) 1. 2. 3. 4. 5. 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”?

I. 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

I. Exotic Species A. 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

I. Exotic Species B. 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 -3 x a year, -3 young per litter Prey on native birds, amphibians, reptiles 2

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

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

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