Title: Invasive Species
1Invasive Species
Class 6 Presentation 1
- The biggest threat to biodiversity after habitat
destruction
2Overview
- Impact
- Examples
- Summary of characteristics of invasive
3Definition
- Organisms (usually transported by humans) which
successfully establish themselves in, and then
overcome, otherwise intact, pre-existing native
ecosystems (World Conservation Union (IUCN)).
4Impact
- 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)
5African 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
6Alien agricultural and forest pests in Canada
2002 Report of the Commissioner of the
Environment and Sustainable Development
7How 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).
8Beech Bark Disease (Nectria coccinea var.
faginata)
9Dandelion
10Gypsy Moth (Lymantria dispar)
11Dutch elm disease (Ophiostoma ulmi)
12Life History Characteristics of Invasive Species
- Plants
- Reproduce sexually and asexually
- Self fertilization
- Lack of seed pre-treatment for germination
- Long period seed on plant
13Can 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
14Life 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
15Life History Characteristics of Agricultural
Invasive Plants
- Herbaceous
- Rapid reproduction
- Dispersed abiotically
16Life History Characteristics of Natural Area
Invasive Plants
- Aquatic or semi-aquatic
- Grasses
- Climbers
- Nitrogen fixers
- Clonal trees
17Life History Characteristics of Invasive Birds
- Dispersal ability
- High rate of population increase
- Large clutch size
- Several clutches/season
- Compete with native species
18Life History Characteristics of Non-Invasive
Organisms
- Lack of pre-adaptation to new environment
- Competition/Predation from native organisms
- Diseases
19Life History Characteristics of Invasive Fresh
Water Fish
- Tolerance to broad range of environments
- Rapid dispersal
- Aggressive behaviour
- Short generation time
20Other features
- Desired by humans
- Close association to human activity
21Summary
- Early germinators (gap grabbers)
- Competitors for resources
- Reallocate resources to growth/reproduction
- Survivors (resist death)
- Swampers (mass germinators)
22Genetics and Evolution
- Good source of research on genetics and evolution
- Rapid directional selection
- Hybridization (interspecific or previously
isolated populations)
23Genetics 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 ?
24Range Expansion
- Rapid expansion large amount of gene flow
- May constrain local adaptation