Download What are invasive species?

Invasive species
Species extinction rates
Causes of Endangerment for
Imperiled Species in the U.S.
100
90
80
70
60
50
40
30
20
10
0
Habitat destruction
Non-native spp.
Pollution
Overharvest
Disease
Wilcove et al. 1998 (data from U.S. Federal Register)
What are invasive species?
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Natives vs. non-natives
Introduced
Aliens
Exotics
Adventives/casuals
Naturalized
What are invasive species?
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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
Acceleration of introductions
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Rates of species introductions in Hawai’i
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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
History of the study of
biological invasions
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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
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An executive order required all federal agencies to refrain
from activities that contribute to introduction and spread of
invasives
How do introductions happen?
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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)
How do introductions
happen?
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Intentional
There is a perceived human benefit from introduction
For example:
 Food
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“Friends”
Accidental
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Pigs, goats, birds, sheep, crops
Hitchhikers
Insects and weeds
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Rats, mice
How do introductions happen?
Natural range expansion
 Ex: Barred Owls have
moved westward into
Spotted Owl range
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Prey
Habitat
Hybridization
Invasiveness
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Undisturbed systems are not safe from
invasion
How do you know if a species will
become invasive?
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Has it invaded elsewhere?
Is the introduction within a range
with similar environmental conditions?
Vector? Continued vector?
Vectors
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Vector
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Examples of vectors of invasive species
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Vehicle or carrier that is able to transfer species,
or route of transmission
Ships
Visitors
Other organisms
Characteristics of good
invaders
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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
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For example: predators, disease, competition
Abundant within large native range
r selected life history traits
Life History Traits
r (fast species)
K (slow species)
Unstable environment, density
independent
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
Impacts of invasives
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Cost
Ecological
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Ecosystem properties and processes
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Disturbance regimes
Hydrology
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Native species loss
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Predation
Hybridize- homogenization of unique regional biota
Competition
Disease
Disturbance
Regime
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Cheat Grass
(Bromus
tectorum)
Hydrology
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American
Beaver (Castor
canadensis)
Anderson et al. 2006
Impacts of invasives
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Cost
Ecological
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Ecosystem properties and processes
Disturbance regimes
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Hydrology
Native species loss
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Predation
Hybridize- homogenization of unique regional biota
Competition
Disease
Predation
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Brown tree
snake (Boiga
irregularis)
Introduced predators can
alter community structure
including trophic structure
From Groom et al (2006)
Predation
Hybridization
Mallard ducks
(Anas platyrhynchos)
theyangpa.tripod.com/
New Zealand Grey (A. superciliosa superciliosa)
Hawaiian (A. wyvilliana)
Florida Mottled (A. fulvigula fulvigula)
Rhymer & Simberloff, 1996
Competition
Disease
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Asian
songbirds
host to avian
pox and
avian
malaria
What do we do about invasives?
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Education, community support
Prevention
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Eradication
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Must be done early
Need community support
Control
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Quarantine, monitoring/early detection, emergency
response
Ongoing, costly
Containment, priority-site, biological control
Biodiversity conservation
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Biotic resistance hypothesis (Elton 1958)
Some of the worst invaders
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MAMMAL
brushtail possum (Trichosurus vulpecula)
goat (Capra hircus)
macaque monkey (Macaca fascicularis)
nutria (Myocastor coypus)
rabbit (Oryctolagus cuniculus)
red fox (Vulpes vulpes)
small Indian mongoose (Herpestes javanicus)
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REPTILE
brown tree snake (Boiga irregularis)
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red-eared slider (Trachemys scripta)
BIRD
Indian myna bird (Acridotheres tristis)
starling (Sturnus vulgaris)
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domestic cat (Felis catus)
grey squirrel (Sciurus carolinensis)
mouse (Mus musculus)
pig (Sus scrofa)
red deer (Cervus elaphus)
ship rat (Rattus rattus)
stoat (Mustela erminea)
red-vented bulbul (Pycnonotus cafer)
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
The palila
(Loxioides bailleui)
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Endangered
Restricted population
The palila
(Loxioides bailleui)
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Food: mamane
pods
and flowers, native
caterpillars in pods
Introduced parasitic
wasps (94%
parasitism at lower
elevational range of
palila)
The palila (Loxioides bailleui)
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Rats, mice, mongoose, feral cats, goats
Alien grasses, increased fire risk