Invasive Species Lec 01 Bio 48803 Althoff

Ideal Invader
LOCAL FLORA - Lecture 15
Dr. Donald P. Althoff
Cane toad
Sericea lespedeza
Feral hog
First….defining “an invasive species”
• Two basic elements:
1 ___________ to the ecosystem
2 ___________ causing environmental,
economic, or human _______
• Synonyms include:
harmful exotic
plant pest
pest plant
nonindigenous aquatic nuisance species
non-native invasive species
An “_________” species….
• Not necessarily harmful….some species
are exotic (or introduced) and they are not
causing measurable problems in
ecosystems or for humans
• Examples: ring-necked pheasant (?)
(in some areas)
Hungarian partridge
• Many exotics are ______________ (some
grain crops, for example)
Some problematic INVASIVES....
Japanese honeysuckle
Japanese knotweed
Autumn olive, Russian olive
Canada thistle
Purple loosestrife
Garlic mustard
Honeysuckle (amur, morrow, &
• Shattercane
• White & yellow sweet clover
Sericea lespedeza
Musk thistle
Nodding thistle
Canada thistle
Bur ragweed
Leafy spurge
_____________(sort of?)
European gypsy moth
Codling moth
Emerald ash borer
Feral hog
Chestnut Blight
Dutch Elm disease
European corn borer
Further west… Pacific Northwest,
some major invasives include:
• Plants: diffuse knapweed, Scotch brome,
Himalayan blackberry
• Fish: Atlantic salmon,
• ______________________: European green crab
• ______________: American bullfrog
• Mammal: nutria
• Bird: European starling
• Insect: gypsy moth
• Disease: white pine blister rust
Some immediate conclusions….
• Invasives can be from _____ taxon
• Invasives can be ___________________, be
ok in one region (native) but problematic in
another (introduced)
• ______ ecosystems seem to be particularly
vulnerable to exotic species—thus causing
problems. This may be because of the
dominance of top-down control of predators
and the ____________________________
________ are processed in aquatic food
Large numbers of invaders, multiple
ways they’ve “arrived”
• The numbers are “huge”….in North America
over the last 200 years more than 70
species of fish, 80 species of mollusks,
2,000 species of plants, and 2,000 species
of insects have been introduced
• “Short list” of how they got here basically
into 2 broad categories:
Ways of ‘getting here’ basically
• Accidentally: earthworms
zebra mussels (ship ballast)
• Deliberate: introduction of crops
introduction as ornamental
introduction of game species
biological control agents
How can nonnatives become problematic?
• In ______________:
1) by displacing native species
2) by hybridizing with native popn
3) by altering ecological factors, thus
disrupting the functioning of
native ecosystems (including
habitat alteration)
4) by transmitting diseases and
parasites not found in native species
How can nonnatives become problematic?
• For __________:
1) by causing health problems
2) by causing economic damage (e.g. in
agriculture) or increasing the costs
of upkeep (e.g., on railway lines,
road, shorelines, military training
According to IUCN
(International Union for Conservation of Nature)
• #1 threat to biodiversity (i.e., reduction of
• #2 threat to biodiversity is invasive alien
What makes an ideal invader?
• One, two, or 3 or more of the
characteristics listed on the next series of
• The _______________ characteristics an
exotic possess, the more potential it has to
become widespread and troublesome.
One way to look at ideal invader traits…
• _______________—i.e., prolific
• _________—easily spread by people, wind,
water or wildlife
• _____________________________—leaf
out earlier (plants) or grow more rapidly to
maturity (plants & animals)
• _________________________—natural
predators, diseases, or other pests that help
control them in native range not present
“Long list” of ideal invader characteristics…
1. High rate of reproduction, pioneer
speices, short generation time
2. Long-lived
3. High dispersal rates
4. Single-parent reproduction (for example,
gravid or pregnant female can colonize
5. Vegetative or clonal reproduction
6. High genetic variablity
7. Phenotypic plasticity
“Long list” of ideal invader characteristics…con’t
8. Broad native range
9. Abundant native range
10. Tolerant of wide range of conditions
(either to “lay dormant” or grow)
11. Habitat generalist
12. Broad diet
13. Gregarious
14. Human commensal
More specifically, for PLANTS
• ___________ and short life cycle:
--go from seed to producing seed
very rapidly (closer to weeks than
• _________ systems (especially compared
to natives for area), rapid early root growth
• ______________
• Able to grow in ___________ of habitats
More specifically, for PLANTS ….con’t
• ______________ of seeds produced
• _____________ and staggered
• __________ method of seed dispersal
• Able to reproduce:
__________ by seed….or…
__________ (vegetatively) by sending
out above- (runners) or belowground (rhizomes) or grow new
plants from cuttings
More specifically, for PLANTS ….con’t
• If reproduce sexually, use insects, birds,
bats, or other pollinators in new location
• Growth and reproduction ________ not
match with native plants
• Provide _____ negatively impacting natives
• Benefit from ____________ (release of
chemicals into the surrounding soil that
prohibits growth of other plants
• __________ to grazing
When can plants with invader
characteristics be helpful?
• _______________ (reproduce by runners and
• Nothing else “takes hold”
• Seed costs for securing/planting native species
are prohibitive and have limited availability
• Food or cover for animal species that is being
threatened to loss of critical habitat—short term
• ?
• ?
Common Characteristics of ___________
Susceptible to Plant Invaders
• _________________ (natural or human-caused)
common. Examples fire, flood, overgrazing,
land clearing for housing and golf courses
• Low _____________
• Added __________ and ____________
• _________ (mesic) conditions (versus dry-xeric)
• Contain __________________ vegetation—(i.e.,
early successional stages)
• __________ slowly from a previous disturbance
• Relatively rich soils _____________________
(ex. riparian zones)