Transcript Powerpoint - People Server at UNCW

Introduced Species
• Introduction of exotic species to new
areas can be the result of:
– Deliberate actions, ignorance of
consequences, or for control of other
species
– Accidental, unknown carriers bring
species to new area
– Natural, rarer, species naturally disperse
to new areas
Natural introduction: Cattle egret, only
species to have reached all 7 continents
From Africa, reached Brazil in 1930s, Florida in
1940s, now widespread in Southeast
Accidental: Whitefly ‘superbug’
• Introduced in Florida in
1980s on poinsettias
• Attack 500+ crop plants;
killing stunting growth
• Deposit sticky residue that
allows mold to grow
• Spread viruses among
crops
• Congregate under leaves,
out of harm from pesticides
Deliberate: Reindeer to sub-Antarctic
Island, South Georgia
Deliberate: Reindeer to sub-Antarctic
Island, South Georgia
• Introduced in early 1900’s by Norwegian whalers
• Reindeer adapted well to climate, new food, and
reproduced
– 1st of 3 introductions in 1909, by 1958: 3,000 animals
• Arctic density 5-7/km2, South Georgia approaches
40-85/km2
– Severe overgrazing: soil erosion,
loss of plant biodiversity, loss of
nesting habitat for birds
http://english.ohmynews.com/articleview/article_view.asp?menu=c10400&no=36521
6&rel_no=1
Deliberate: Kudzu
-- Kudzu vine introduced to
U.S. in 1876 at the
Philadelphia Centennial
Exposition
-- Plantings in southeast
encouraged to prevent soil
erosion, as a forage plant,
and ornamental until listed as
pest species in 1953
-- Rapid growth: 60 feet/season
or ~1 foot/day
www.firehow.com
Keystone exotics
• Species that change entire community structure
– In Southeast, Honeysuckle and Kudzu smother native
forests
http://www.treehugger.com/renewable-energy/biofuel-feedstocks-gain-a-new-candidate-kudzu.html
http://www.ppws.vt.edu/scott/weed_id/lonja.htm
Keystone exotics
• Species that change entire community structure
– In Southeast, Honeysuckle and Kudzu smother native
forests
• Hyacinths in Everglades
Keystone exotics
• Species that change entire community structure
– In Southeast, Honeysuckle and Kudzu smother native
forests
• Hyacinths in Everglades
• Livestock—grazing in western US
– Once desert grassland, now gone
Erosion in New Mexico from 100+ yrs of overgrazing
Loss of cultural remains ~800 yrs old
Spotted Knapweed in western U.S and Canada
--arrived from Europe to British Columbia as an
accidental introduction\
--takes over large areas of open grassland
--except for sheep, most grazing animals avoid it
--produces an allelopathy to prevent other plants from
growing around it
Most introductions fail
• Wrong ecological conditions for survival,
can’t compete with natives (niches full)
– Egrets reached Antarctica, couldn’t survive
there
• Warming trend may change conditions and
some introductions could succeed
What factors allow for successful
invasions?
1) Small organisms do best.
– Rapid generations and r-selected reproduction
– Evolve and adapt to new conditions quickly
2) Easily transported, or not detected
– Small insects on plants, fungi
– 40% crop pests in US are insects
– Seeds on shoes can be carried long distances
– Ballast tanks on ships
What factors allow for successful
invasions?
3) Favorable habitats present in new area
– May have fewer or no predators
– Acts as release from counteradaptations
– Islands particularly susceptible as often have
more open niches, lower species diversity then
mainland
e.g., cats, goats, pigs, rats
Stephens Island Wren, New Zealand
Eradication
% population remaining
• Once a species becomes established,
can be very difficult to eradicate
0
100
Cost/effort to eradicate
Eradication: Biological controls
• Use natural predators from invaders
home community
• Sometimes successful
– Australia introduced dung beetle to solve
livestock dung and fly problem
Eradication with Genomics
• Genetic engineering: a new weapon
– Rabbits introduced in Australia being controlled
by a manufactured virus, causes sterility
– Lots of experiments prior to release
– Unintended consequences—will virus mutate
and spread to other native species?
The Infamous Cane Toad
• Native to South America
• Introduced to Australia in 1930s for
biological control of cane grub
• Became part of local culture
• No natural predators, spread rapidly
• Impacts native wildlife with poison glands
Introduced Species examples:
Know:
1) Why/how they were introduced
2) Why they are so successful
3) Why are they difficult to eradicate
4) Problems caused? Solutions?
whitefly ‘superbug’
kudzu, honeysuckle, hyacinth, and knapweed as
keystone exotics
cane toad as deliberate introduction, biological control
cattle egret as natural introduction