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Invasive Species

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Title: Invasive Species


1
Invasive Species
Class 6 Presentation 1
  • The biggest threat to biodiversity after habitat
    destruction

2
Overview
  • Impact
  • Examples
  • Summary of characteristics of invasive

3
Definition
  • Organisms (usually transported by humans) which
    successfully establish themselves in, and then
    overcome, otherwise intact, pre-existing native
    ecosystems (World Conservation Union (IUCN)).

4
Impact
  • Economic impact billions of dollars/year (See
    next slide)
  • Impacts on biodiversity
  • Research/Regulation/Control/Management
  • 30,000 non-native spp in N Am since colonization
  • 30 of 4,200 vascular plant spp in Canada exotic
    (not all invasive)

5
African land snail (Achatina fulica) in Florida
  • 3 snails smuggled in by boy returning from Hawaii
    in 1966
  • Grandmother released them in her garden
  • Problem noticed in 1969
  • Mailed info to 150,000 houses
  • Infestations found 25 km outside initial area
  • Eradication program started, 18k snails found
  • Cost US 1 million

6
Alien agricultural and forest pests in Canada
2002 Report of the Commissioner of the
Environment and Sustainable Development
7
How do they get around?
  • Aquatic ballast tanks in ships (simple solution
    to eliminate problem exchange water at sea)
  • Non-deliberate most linked to human activity
  • Deliberate
  • soil erosion prevention kudzu
  • Feel like home birds and game fish
  • Some related to agriculture, ornamentals,
    captivity (e.g. aquarium trade).

8
Beech Bark Disease (Nectria coccinea var.
faginata)
9
Dandelion
10
Gypsy Moth (Lymantria dispar)
11
Dutch elm disease (Ophiostoma ulmi)
12
Life History Characteristics of Invasive Species
  • Plants
  • Reproduce sexually and asexually
  • Self fertilization
  • Lack of seed pre-treatment for germination
  • Long period seed on plant

13
Can we detect invasiveness?
  • Early attempts to look for life traits of a
    species that would link that spp with potential
    invasiveness have failed. Why?
  • Best bet is to study those that have become
    invasive high probability for being invasive in
    another similar ecosystem

14
Life History Characteristics of Invasive Species
  • Exotic spp often have fewer infections and
    predators.
  • Drop in all diseases amoung European plants in N
    Am 77
  • Ave of parasites in home range 16
  • Ave parasites in new range 3

D. Pimental et al, Nature, Feb 6, 2003
15
Life History Characteristics of Agricultural
Invasive Plants
  • Herbaceous
  • Rapid reproduction
  • Dispersed abiotically

16
Life History Characteristics of Natural Area
Invasive Plants
  • Aquatic or semi-aquatic
  • Grasses
  • Climbers
  • Nitrogen fixers
  • Clonal trees

17
Life History Characteristics of Invasive Birds
  • Dispersal ability
  • High rate of population increase
  • Large clutch size
  • Several clutches/season
  • Compete with native species

18
Life History Characteristics of Non-Invasive
Organisms
  • Lack of pre-adaptation to new environment
  • Competition/Predation from native organisms
  • Diseases

19
Life History Characteristics of Invasive Fresh
Water Fish
  • Tolerance to broad range of environments
  • Rapid dispersal
  • Aggressive behaviour
  • Short generation time

20
Other features
  • Desired by humans
  • Close association to human activity

21
Summary
  • Early germinators (gap grabbers)
  • Competitors for resources
  • Reallocate resources to growth/reproduction
  • Survivors (resist death)
  • Swampers (mass germinators)

22
Genetics and Evolution
  • Good source of research on genetics and evolution
  • Rapid directional selection
  • Hybridization (interspecific or previously
    isolated populations)

23
Genetics and Colonization
  • Pre-adaptation important
  • Adaptive evolution also important
  • Rate of change to natural selection proportional
    to amount of additive genetic variation present
  • Multiple introductions genetic diversity ?

24
Range Expansion
  • Rapid expansion large amount of gene flow
  • May constrain local adaptation
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