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Invasive species

Invasive species

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Invasive species

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  1. Invasive species

  2. Species extinction rates

  3. Causes of Endangerment forImperiled Species in the U.S. Wilcove et al. 1998 (data from U.S. Federal Register)

  4. What are invasive species? • Natives vs. non-natives • Introduced • Aliens • Exotics • Adventives/casuals • Naturalized

  5. What are invasive species? • Federal Government’s Executive Order defined as: an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health

  6. Acceleration of introductions • Rates of species introductions in Hawai’i • Natural rate: 1 established introduction every 100,000 years • After Polynesians: 1 established introduction every 50,000 years • Since Europeans: 1 established introduction every 0.25 years, or 4 per year • Approximately 1000 plant species established in the last 200 years out of about 5000 introduced

  7. History of the study of biological invasions • Darwin’s Origin of the Species (1859) • C. Elton’s book in 1958 • Early 1980’s, biological invasions began to be recognized as problematic: call for assessment of scientific understanding • In the early 90’s, invasions were still not given too much attention • 1999 – BIG CHANGE • An executive order required all federal agencies to refrain from activities that contribute to introduction and spread of invasives

  8. How do introductions happen? • Most introduced species do not survive • Of those that survive, many do not cause “severe harm” to native ecosystems, species or humans (only 15% of establishments)

  9. How do introductions happen? • Intentional There is a perceived human benefit from introduction For example: • Food • Pigs, goats, birds, sheep, crops • “Friends” • Accidental • Hitchhikers • Insects and weeds • Rats, mice

  10. How do introductions happen? Natural range expansion • Ex: Barred Owls have moved westward into Spotted Owl range • Prey • Habitat • Hybridization

  11. Invasiveness • Undisturbed systems are not safe from invasion • How do you know if a species will become invasive? • Has it invaded elsewhere? • Is the introduction within a range with similar environmental conditions? • Vector? Continued vector?

  12. Vectors • Vector • Vehicle or carrier that is able to transfer species, or route of transmission • Examples of vectors of invasive species • Ships • Visitors • Other organisms

  13. Characteristics of good invaders • Tolerant of wide range of environmental conditions • Originate from area with diverse biota • Generalist diet • Ecological range overlaps with potential vectors • Natural population controls not present • For example: predators, disease, competition • Abundant within large native range • r selected life history traits

  14. Life History Traits

  15. Impacts of invasives • Cost • Ecological • Ecosystem properties and processes • Disturbance regimes • Hydrology • Native species loss • Predation • Hybridize- homogenization of unique regional biota • Competition • Disease

  16. Disturbance Regime • Cheat Grass (Bromus tectorum)

  17. Hydrology • American Beaver (Castor canadensis) Anderson et al. 2006

  18. Impacts of invasives • Cost • Ecological • Ecosystem properties and processes • Disturbance regimes • Hydrology • Native species loss • Predation • Hybridize- homogenization of unique regional biota • Competition • Disease

  19. Predation • Brown tree snake (Boiga irregularis)

  20. Introduced predators can alter community structure including trophic structure From Groom et al (2006)

  21. Predation

  22. Hybridization New Zealand Grey (A. superciliosa superciliosa) Hawaiian (A. wyvilliana) Florida Mottled (A. fulvigula fulvigula) Mallard ducks (Anas platyrhynchos) theyangpa.tripod.com/ Rhymer & Simberloff, 1996

  23. Competition

  24. Disease • Asian songbirds host to avian pox and avian malaria

  25. What do we do about invasives? • Education, community support • Prevention • Quarantine, monitoring/early detection, emergency response • Eradication • Must be done early • Need community support • Control • Ongoing, costly • Containment, priority-site, biological control • Biodiversity conservation • Biotic resistance hypothesis (Elton 1958)

  26. Some of the worst invaders • MAMMAL brushtail possum (Trichosurus vulpecula)domestic cat (Felis catus) goat (Capra hircus)grey squirrel (Sciurus carolinensis) macaque monkey (Macaca fascicularis)mouse (Mus musculus) nutria (Myocastor coypus)pig (Sus scrofa) rabbit (Oryctolagus cuniculus)red deer (Cervus elaphus) red fox (Vulpes vulpes) ship rat (Rattus rattus) small Indian mongoose (Herpestes javanicus) stoat (Mustela erminea) • REPTILE brown tree snake (Boiga irregularis)red-eared slider (Trachemys scripta) • BIRD Indian myna bird (Acridotheres tristis) red-vented bulbul (Pycnonotus cafer) starling (Sturnus vulgaris) • AMPHIBIAN bullfrog (Rana catesbeiana) cane toad (Bufo marinus) Caribbean tree frog (Eleutherodactylus coqui) **From www.issg.org – 100 of the world’s worst invasive alien species

  27. The palila (Loxioides bailleui) • Endangered • Restricted population

  28. The palila (Loxioides bailleui) • Food: mamane pods and flowers, native caterpillars in pods • Introduced parasitic wasps (94% parasitism at lower elevational range of palila)

  29. The palila (Loxioides bailleui) • Rats, mice, mongoose, feral cats, goats • Alien grasses, increased fire risk