1. 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

2. 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

3. 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
Introduced in Florida in 1980s on poinsettias, attacks 500+ crop plants sucking juices from fruit, leaves, stems. Kill or cause stunted growth, congregate under leaves out of harm from pesticides, resistant to most pesticides, deposit sticky residue on fruit and leaves that allows mold to grow, transmits diseases (viruses) to different crops, problem in fields and greenhouses.

4. Deliberate: Reindeer to sub-Antarctic Island, South Georgia

5. 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

6. 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
Kill trees and plants by smothering them, or weight breaks them down

7. Keystone exotics Species that change entire community structure
In Southeast, Honeysuckle and Kudzu smother native forests

8. Keystone exotics Species that change entire community structure
In Southeast, Honeysuckle and Kudzu smother native forests
Hyacinths in Everglades

9. 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

10. Erosion in New Mexico from 100+ yrs of overgrazing

11. Loss of cultural remains ~800 yrs old

12. 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

13. 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

14. What factors allow for successful invasions?
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

15. 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

16. Stephens Island Wren, New Zealand

17. Eradication
Once a species becomes established, can be very difficult to eradicate
% population remaining
100
Cost/effort to eradicate

18. Eradication: Biological controls
Use natural predators from invaders home community
Sometimes successful
Australia introduced dung beetle to solve livestock dung and fly problem

19. 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?

20. 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

21. 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