Transcript Invasive species - Plant Ecology at Syracuse

Species invasions
Bio 415/615
Questions
1. Why is the world primed to be subject to
species invasions?
2. What is ‘biotic resistance’ and how does it
apply to species invasions?
3. What are 3 potential explanations of how a
species becomes an invader?
4. What is Darwin’s naturalization hypothesis?
"We must make no mistake:
We are seeing one of the
Great historical convulsions
in the world's flora and
fauna. We might say, with
Professor Challenger,
standing on Conan Doyle's
'Lost World', with his black
beard jutting out: 'We have
been privileged to be present
at one of the typical decisive
battles of history--the
battles which have
determined the fate of the
world.'"
C. S. Elton, The Ecology of
Invasions by Plants and
Animals, 1958
What’s a biological invader?
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DEFINITIONS of Invasion Biology
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EXOTIC, ALIEN Not “Originally” “Here”
INTRODUCED, NON-NATIVE
NATURALIZED
Self-sustaining exotic
INVASIVE
Spreading exotic
PEST
Has Negative Impact
BENEFICIAL
Has Positive Impact
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“EXOTIC” AND CONSERVATION
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Historically Offensive: all exotics, some conservationists
Not original, not natural, out of place
Causes impacts: some exotics, all conservationists
Replace native species, change ecosystem function
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Typha angustifolia (cattail)
Probably only in SE NY (coast)
before recent spread along
salted roadways
There is no formal agreed upon system of classification for exotic
species.
Points of Disagreement:
1. Native Range Expansion vs. Exotic Species –
Cattle Egrets – Native or Exotic in South America? They dispersed
under their own power, but colonized an anthropogenic
environment.
2. Reintroduction to Native Range vs. Exotic Species –
Horses – Native or Exotic to North America? They were driven
extinct 10,000 yrs bp, but were reintroduced by the Spanish.
Assumptions/Conditions:
1.
When?
2. With human assisted dispersal or colonization?
Taxonomic bias of scientists, e.g. birds vs. plants, with dispersal
How & why are exotic species introduced?
1. Some arrive by their own power of dispersal
2. The remainder are transported by humans
Intentionally:
Naturalization Programs
Horticulture
Agriculture
Animal Husbandry
NZ, US
Unintentionally:
Ballast
Agricultural/Horticultural Weeds
Phoresy (hooves, fur, guts, etc.)
Does ‘invasion’ differ from
natural migration?
• Spatial extent of migration (noncontinuous)
• Number of migration individuals
• Genotypes (‘core’ versus ‘peripheral’)
• Migration coincident with biotic
associates (enemies, mutualists)
Invader vignettes
Kudzu (Pueraria montana)
Kudzu – a case history
Introduced to the U.S. in 1876, centennial celebration
Gift from the Japanese government
Gardeners loved it and started to plant it
1920’s promoted as a forage plant for livestock
1930’s Civilian Conservation Core planted it for soil
erosion
1940’s touted as a miracle vine and clubs were formed
1953 federal government stopped advocating its use
Grows up to 60 feet per year, or 1 ft on a hot summer day
Covers everything: trees, houses, farm equipment, etc.
Distributed primarily in the deep south, where it covers
ca. 2 million acres of land
Zebra mussel (Dreissena polymorpha)
• native to SW Russia
(Caspian Sea region)
• females produce>
30,000 eggs each yr
• detected in US in
1988 (Great Lakes),
probably via ship ballast
• filter feeders
• problem for water
treatment plants
• costs $5 billion / yr
• crowd out native
mussels
Zebra Mussel spread
Passer domesticus – house sparrow
(Eurasian)
• introduced to many US
cities in late 1800s for
pest control
• is now perhaps the most
common songbird in the
US (maybe the world)
• directly competes with
other cavity-nesting
songbirds
• one of only 3 birds in the
US not protected by law
House Sparrow – Passer domesticus
Cheat grass (Bromus tectorum)
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From S Europe and SW Asia
Winter annual, highly flammable
Increases fire return frequencies
Has transformed large former sagebrush and grass lands of the
American West
• Can be dangerous to livestock
• Causes hundreds of millions $$$ each year in control and
livestock loss
Brown tree snake
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Native to Australia
Introduced across Pacific
Detected in Guam in 1950s
Large population expansion on islands
Likely cause of extinction of 9/12 of
Guam’s native birds, and 2/11 lizards
• Frequent power outages
• U Hawaii study predicted >400 million
$$$ annual cost to Hawaii economy
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Emerald ash borer
Asian longhorned beetle
Gypsy moth
Balsam woolly adelgid
Hemlock woolly adelgid
Insects
Invasive mammals
• European wild boar
• Mongoose
• Rats
Invasive human diseases
• West Nile virus
– African, maybe 1000 years old
– Found on US East Coast in 1999
– Various animal vectors (birds, insects, horses)
• SARS
– Severe acute respiratory syndrome (virus)
– First outbreak in China in 2002
– Spread in 2003 to many North American cities
• Monkeypox
– African, spread to US in 2003 to pet prairie dog owners (via
an infected pet store Gambian pouched rat in TX)
What about life on earth sets
the stage for species invasions?
Darwin (1859):
In considering the distribution of organic
beings over the face of the globe, the first
great fact which strikes us is that neither the
similarity nor the dissimilarity of the
inhabitants of various regions can be wholly
accounted for by climatal and other physical
conditions…
There is hardly a climate or condition in the
Old World which cannot be paralleled in the
New…[yet] how widely different their organic
productions!
Floristic regions and Köppen-Geiger climate zones
Warm-temperature, fully humid, hot summer climate in blue
Why are some regions more
invaded than others?
1. Biotic resistance: more diverse
communities consume more resources,
leave less available to potential
invaders
Biotic resistance?
• Experimental evidence says yes
(sometimes)
Fargione & Tilman 2005
Biotic resistance?
• Observational evidence says NO (most
of the time)
Why are some regions more
invaded than others?
1. Biotic resistance: more diverse
communities consume more resources,
leave less available to potential
invaders
2. Resource supply and demand:
processes like disturbance make
resources available to invaders
Davis et al. 2000
Why are some regions more
invaded than others?
1. Biotic resistance: more diverse
communities consume more resources,
leave less available to potential
invaders
2. Resource supply and demand:
processes like disturbance make
resources available to invaders
3. Propagule pressure: communities
differ in exposure to invaders
More plantations, more invasions
Rejmanek et al.
Greater years since introduction,
more invasions
Rejmanek et al.
What makes an organism
invasive?
1. Innate biology: preadaptation, empty
niche, weediness, competitiveness, etc
Innate Biology: Weediness
Innate Biology: Weediness
Plant Traits for Prediction
“…there are no specific traits that
alone predict invasiveness…Rather
the best single predictor is what a
species has done in other places…”
D’Antonio et al. 2004
• “The overriding frustration of invasion
ecology.”
Rejmanek et al. 2005
What makes an organism
invasive?
1. Innate biology: preadaptation, empty
niche, weediness, competitiveness, etc
2. Enemy release
Enemy release hypothesis (ERH)
Biotic resistance hypothesis (BRH)
Mitchell & Power 2003
What makes an organism
invasive?
1. Innate biology: preadaptation, empty
niche, weediness, competitiveness, etc
2. Enemy release
3. Novel weapons / rapid evolution of
invasiveness
Novel weapons via phytochemicals
Callaway et al. 2008
Alliaria petiolata: stronger effects
on mycorrhizas (and their plant
associates) in U.S. than in Europe
Callaway & Aschehoug 2004
Centaurea spp. widespread in
North America produce root
exudates with strong phytotoxic
effects on North American species
but weak effects on neighbors in
the native range (Caucasus Mtns)