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Species invasions

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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? - PowerPoint PPT Presentation
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Species invasions Bio 415/615
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Page 1: Species invasions

Species invasions

Bio 415/615

Page 2: Species invasions

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?

Page 3: Species invasions

"We must make no "We must make no mistake: We are seeing mistake: We are seeing one of the Great one of the Great historical convulsions in historical convulsions in the world's flora and the world's flora and fauna. We might say, fauna. We might say, with Professor with Professor Challenger, standing on Challenger, standing on Conan Doyle's 'Lost Conan Doyle's 'Lost World', with his black World', with his black beard jutting out: 'We beard jutting out: 'We have been privileged to have been privileged to be present at one of the be present at one of the typical decisive battles typical decisive battles of history‑‑the battles of history‑‑the battles which have determined which have determined the fate of the world.'" the fate of the world.'"

C. S. Elton, C. S. Elton, The Ecology The Ecology of Invasions by Plants of Invasions by Plants and Animalsand Animals, 1958, 1958

Page 4: Species invasions

What’s a biological invader?

Page 5: Species invasions

______________________________________________________

DEFINITIONS of Invasion Biology____________________________________________________

EXOTIC, ALIEN Not “Originally” “Here”INTRODUCED, NON-NATIVE

NATURALIZED Self-sustaining exotic

INVASIVE Spreading exotic

PEST Has Negative Impact

BENEFICIAL Has Positive Impact_____________________________________________________

Page 6: Species invasions

____________________________________________________

“EXOTIC” AND CONSERVATION

_______________________________________________

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

____________________________________________________

Typha angustifolia (cattail)

Probably only in SE NY (coast) before recent spread along salted roadways

Page 7: Species invasions

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

Page 8: Species invasions

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 NZ, US

HorticultureAgricultureAnimal Husbandry

Unintentionally:BallastAgricultural/Horticultural WeedsPhoresy (hooves, fur, guts, etc.)

Page 9: Species invasions

Does ‘invasion’ differ from natural migration?

• Spatial extent of migration (non-continuous)

• Number of migration individuals• Genotypes (‘core’ versus

‘peripheral’)• Migration coincident with biotic

associates (enemies, mutualists)

Page 10: Species invasions

Invader vignettes

Page 11: Species invasions

Kudzu (Pueraria montana)

Page 12: Species invasions

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

Page 13: Species invasions

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

Page 14: Species invasions

Zebra Mussel spread

Page 15: Species invasions

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

Page 16: Species invasions

House Sparrow – Passer domesticus

Page 17: Species invasions

Cheat grass (Bromus tectorum)

• 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

Page 18: Species invasions

Brown tree snake

• 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

Page 19: Species invasions

Insects• Emerald ash borer• Asian longhorned beetle• Gypsy moth• Balsam woolly adelgid• Hemlock woolly adelgid

Page 20: Species invasions

Invasive mammals

• European wild boar• Mongoose• Rats

Page 21: Species invasions

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)

Page 22: Species invasions

What about life on earth sets the stage for species

invasions?

Page 23: Species invasions
Page 24: Species invasions

Darwin (1859):Darwin (1859):

In considering the distribution of organic In considering the distribution of organic beings over the face of the globe, the first beings over the face of the globe, the first great fact which strikes us is that neither great fact which strikes us is that neither the similarity nor the dissimilarity of the the similarity nor the dissimilarity of the inhabitants of various regions can be inhabitants of various regions can be wholly accounted for by climatal and other wholly accounted for by climatal and other physical conditions…physical conditions…

There is hardly a climate or condition in the There is hardly a climate or condition in the Old World which cannot be paralleled in the Old World which cannot be paralleled in the New…[yet] how widely different their New…[yet] how widely different their organic productions!organic productions!

Page 25: Species invasions

Floristic regions and Köppen-Geiger climate zones

Warm-temperature, fully humid, hot summer climate in blue

Page 26: Species invasions

Why are some regions more invaded than others?

1. Biotic resistance: more diverse communities consume more resources, leave less available to potential invaders

Page 27: Species invasions

Biotic resistance?• Experimental evidence says yes

(sometimes)

Fargione & Tilman 2005Fargione & Tilman 2005

Page 28: Species invasions

Biotic resistance?• Observational evidence says NO

(most of the time)

Page 29: Species invasions

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

Page 30: Species invasions

Davis et al. 2000

Page 31: Species invasions

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

Page 32: Species invasions

More plantations, more invasionsRejmanek et al.Rejmanek et al.

Page 33: Species invasions

Greater years since introduction, more invasions

Rejmanek et al.Rejmanek et al.

Page 34: Species invasions

What makes an organism invasive?

1. Innate biology: preadaptation, empty niche, weediness, competitiveness, etc

Page 35: Species invasions

Innate Biology: Weediness

Page 36: Species invasions

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. 2004D’Antonio et al. 2004

• “The overriding frustration of invasion ecology.”

Rejmanek et al. 2005Rejmanek et al. 2005

Innate Biology: Weediness

Page 37: Species invasions

What makes an organism invasive?

1. Innate biology: preadaptation, empty niche, weediness, competitiveness, etc

2. Enemy release

Page 38: Species invasions

Enemy release hypothesis (ERH)Biotic resistance hypothesis (BRH)

Mitchell & Power 2003

Page 39: Species invasions

What makes an organism invasive?

1. Innate biology: preadaptation, empty niche, weediness, competitiveness, etc

2. Enemy release3. Novel weapons / rapid evolution of

invasiveness

Page 40: Species invasions

Novel weapons via phytochemicals

Callaway & Aschehoug 2004

Alliaria petiolata: stronger effects on mycorrhizas (and their plant associates) in U.S. than in Europe

Callaway et al. 2008

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)


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