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Class 6 Presentation 1. Invasive Species. The biggest threat to biodiversity after habitat destruction. Overview. Impact Examples Summary of characteristics of invasive. Definition.

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Invasive Species

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invasive species

Class 6

Presentation 1

Invasive Species

The biggest threat to biodiversity after habitat destruction

  • Impact
  • Examples
  • Summary of characteristics of invasive

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

  • 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)
african land snail achatina fulica in florida
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

Alien agricultural and forest pests in Canada

2002 Report of the Commissioner of the Environment and Sustainable Development

how do they get around
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).
life history characteristics of invasive species
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
can we detect invasiveness
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
life history characteristics of invasive species14
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

life history characteristics of agricultural invasive plants
Life History Characteristics of Agricultural Invasive Plants
  • Herbaceous
  • Rapid reproduction
  • Dispersed abiotically
life history characteristics of natural area invasive plants
Life History Characteristics of Natural Area Invasive Plants
  • Aquatic or semi-aquatic
  • Grasses
  • Climbers
  • Nitrogen fixers
  • Clonal trees
life history characteristics of invasive birds
Life History Characteristics of Invasive Birds
  • Dispersal ability
  • High rate of population increase
    • Large clutch size
    • Several clutches/season
  • Compete with native species
life history characteristics of non invasive organisms
Life History Characteristics of Non-Invasive Organisms
  • Lack of pre-adaptation to new environment
  • Competition/Predation from native organisms
  • Diseases
life history characteristics of invasive fresh water fish
Life History Characteristics of Invasive Fresh Water Fish
  • Tolerance to broad range of environments
  • Rapid dispersal
  • Aggressive behaviour
  • Short generation time
other features
Other features
  • Desired by humans
  • Close association to human activity
  • Early germinators (gap grabbers)
  • Competitors for resources
  • Reallocate resources to growth/reproduction
  • Survivors (resist death)
  • Swampers (mass germinators)
genetics and evolution
Genetics and Evolution
  • Good source of research on genetics and evolution
    • Rapid directional selection
    • Hybridization (interspecific or previously isolated populations)
genetics and colonization
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 

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