Invasive species

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 Governments 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 Hawaii
• 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

• Darwins Origin of the Species (1859)
• C. Eltons book in 1958
• Early 1980s, biological invasions began to be
  recognized as problematic call for assessment
  of scientific understanding
• In the early 90s, 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
  r (fast species) Unstable environment, density independent K (slow species) Stable environment, density dependent interactions
Organism size Small Large
Energy used to make each individual Low High
Offspring produced Many Few
Timing of maturation Early Late (with much parental care)
Life expectancy Short Long
Lifetime reproductive events One More than one
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 worlds 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