* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download INVASIVE SPECIES - Department of Zoology, UBC
Survey
Document related concepts
Molecular ecology wikipedia , lookup
Latitudinal gradients in species diversity wikipedia , lookup
Ecological fitting wikipedia , lookup
Occupancy–abundance relationship wikipedia , lookup
Biodiversity action plan wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Theoretical ecology wikipedia , lookup
Habitat conservation wikipedia , lookup
Invasive species wikipedia , lookup
Reconciliation ecology wikipedia , lookup
Transcript
Announcements: • Midterm paper due next Monday 25 Oct. • Tutorial next week: Read the description of the final project on the course website; think about possible topics. • Tree data due by next Tuesday 26 Oct. • Lectures next week (I’ll be away): Kai Chan on Monday; Judy Myers (Biocontrol) on Wed. (guest material will be on the final) COURSE SCHEDULE I. Foundations of discipline. II. Scientific underpinnings. III. Threats to biodiversity. IV. Solutions. V. Perspectives & case studies. Today (& next Wed.): Invasion Biology Last time (& next time): Conservation Economics • FINAL EXAM: Monday 20 December, 3:30pm INVASIVE SPECIES Some exotics in southwestern B.C. English ivy Eastern grey squirrel Should we attempt to eradicate these and other exotic species? • The invasion process • Ecological and economic impacts • Pathways of introduction • Predictors of invasive “success” • Methods of prevention and control A.Yes Japanese knotweed Atlantic salmon B. No Himalayan blackberry C. Depends on the species House sparrow 1 Some exotic species in North America THE INVASION PROCESS Uptake from native range Transfer via vector Cattle Release in new region Establishment Tomato Perennial rye grass Population increase & range expansion Wheat Williamson & Fitter (1996) Ecology What fraction of plant species introduced to a new continent ultimately become “invasive”? The “tens rule”: A. 1/2 1/10 species that arrive will survive B. 1/5 1/10 species that survive will establish C. 1/10 1/10 species that establish will become “invasive” THE INVASION PROCESS Uptake from native range Transfer via vector Release in new region D. 1/100 Establishment The tens rule is not to be taken literally, but it captures the result that only a small proportion of introduced species ever actually becomes a concern to people Population increase & range expansion E. 1/1000 Williamson & Fitter (1996) Ecology 2 Ecological and economic effects of invasive species Dilution and competition: Even if no (little) regional extinction – effects on abundance and local diversity e.g., Purple loosestrife in temperate wetlands Ecological impacts - “Dilution” of native biodiversity - Direct impact on native species: competition, predation, disease - Ecosystem level change Introduced predators can cause great damage (including extinction), particularly on islands with “naïve” prey Introduced species can alter ecosystem processes e.g., Exotic plants in Hawaii C4 grasses increase fire frequency, alter ecosystem properties and vegetation change Hawaii Volcanoes National Park Brown tree snakes Feral cats Exotic nitrogen fixer (Myrica faya) colonizes volcanic sites, altering nutrient cycling and succession Vitousek et al. (1987) Science Mack & D’Antonio (2001) Ecological Applications 3 Ecological and economic effects of invasive species Economic impacts Zebra mussels in eastern North American waterways Clogging of water intake pipes (among other things) - Reduce agricultural/pasture productivity - Forest damage (insect pests) - Clog water intakes (zebra mussels) - Choke waterways (aquatic plants) - Health costs (introduced diseases) Estimate: ~50,000 non-native species costs the U.S. economy >$130 billion per year Pimentel et al. (2000) BioScience Damage to forests by exotic insects: The hemlock woolly adelgid Agricultural pests: Exotic insects that damage our food plants European corn borer 4 Some important pathways of introduction Intentional introduction - Early European settlers wanting to feel “at home” - Horticulture and the pet trade - Food/forage organisms: fish, pasture grasses etc. - Biocontrol agents For species that have been introduced to a new continent, the most consistent predictor of which ones will become invasive is: A. Reproductive rate B. Body size Unintentional introduction - Ship ballast water - Grain shipments - “Stowaways” (e.g., brown tree snake) Determinants of establishment: The most consistent predictor of success is “propagule pressure” – how many individuals introduced and how often Birds introduced to New Zealand C. Number of individuals introduced D. Habitat/diet specialization Determinants of establishment: It has proven difficult to predict success based on species traits, but there are exceptions… Introduced fish in the Great Lakes Successfully established Failure to establish Success or failure to establish correctly predicted for 43/45 species Veltman et al. (1996) American Naturalist Kolar & Lodge (2002) Science 5 Determinants of invasion: the enemy-release hypothesis Degree of “enemy release” predicts invasiveness of plant species in the U.S. Proportion of states that list species as “noxious” Proportion of organizations that list species as “invasive” Determinants of invasion What makes a habitat more or less invasible? - Climatic match to tolerances of invaders - Empty niches (islands) - Lack of enemies of invaders - Resource availability - Disturbance - Anthropogenic habitats (human commensals) - Naïve prey (islands) How many pathogenic fungi & viruses in introduced range vs. native range Mitchell & Power (2003) Nature Are the issues faced with exotic species any different than those faced with native species? Ecology 101: If we monkey around with a food web, major changes can happen (abundances of other species, fluxes of nutrients, energy, etc.). BUT, not necessarily… 6 Prevention, eradication & control of exotic species Most exotic species are innocuous, and many native species have become pests (pine beetles, deer, etc.) Prevention Uptake from native range Prevention, eradication & control of exotic species Transfer via vector Prevention of introduction: e.g., exchange ballast water mid-ocean Transfer via vector Release in new region Control Eradication Control Eradication Population increase & range expansion Population increase & range expansion Uptake from native range Release in new region Establishment Establishment Prevention, eradication & control of exotic species Prevention Prevention Uptake from native range Transfer via vector Release in new region Control Eradication Are the issues faced with exotic species any different than those faced with native species? Establishment Population increase & range expansion 7 Prevention, eradication & control of exotic species Transfer via vector Prevention, eradication & control of exotic species Uptake from native range Prevention Prevention Uptake from native range Eradication of mammals on islands: Feral pigs on Santiago Island, Galapagos ~19,000 animals killed by hunting & poison over 30 years Transfer via vector Release in new region Control Eradication Release in new region Control Eradication Biological control: Introducing natural enemies to control invasive species Establishment Population increase & range expansion Establishment Population increase & range expansion Would be extremely difficult on a mainland Cruz et al. (2005) Biological Conservation 8