Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ENVR 202 (18-25) > 20- Invasive Species > Flashcards

20- Invasive Species Flashcards

1
Q

what are the harmful impacts of echium plantagineum (invasive plant species) in Australia

A
  • forms dense monocultures, outcompeting native plants
  • much more drought resistant than native species –> allows it to get a foothold
  • partial toxicity in ungulates –> causes weight loss and liver issues in cattle and horses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

something to keep in mind when defining invasive species

A

Definition of an invasive species is relative
- has to do with our perceived impact of the species on its novel habitat
(often difficult to accurately measure its real impact)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is an introduced species

A

(aka non-native species or exotic species)
= a species which has been introduced to a habitat that it has not historically been found in
(note that this definition says nothing about the impact of that species)
- not the same as a species which has been extirpated and then reintroduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is an invasive species

A

= an introduced species which is having a negative impact on the novel environment it is in
(novel environment = an environment a species has never inhabited before)
- note that an invasive species must be an introduced species
(native species can also harm their environment in certain situations, but there are not considered invasive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is a negative impact

A

= any impact on an environment which reduces/ degrades:

  1. species diversity
  2. the total number of individual organisms
  3. the abiotic and/or biotic environment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how are invasive species uninentionally introduced

A

Most often an indirect result of international travel:

  • shipping and trade
  • tourism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

steps of the ‘‘invasion process”

A
  1. transport
  2. establishment
  3. lag phase
  4. spread
  5. impact
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

step #1 of the invasion process

A

TRANSPORT
- species must be able to survive transport
- must survive extended period in suboptimal conditions
(like in the hold of a ship)
- easy for small opportunist species
(not so easy for something like a tiger)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

step #2 of the invasion process

A

ESTABLISHMENT

  • once successfully transported, need to become established in the novel environment
  • establishment:
    1. survival
    2. successful reproduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

characteristics of environments tend to have the greatest number of introduced species

A
  • warm throughout the year
  • consistent rainfall throughout the year
  • stable weather throughout the year
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what do “waves of introductions” for a single species allow

A

Allow gene flow between source and founder populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

step #3 of the invasion process

A

LAG PHASE
A newly established species initially has low population numbers
- must increase in numbers before it can successfully begin spreading in the novel habitat
Lag phase = the period of time between when a species is first introduced in a novel environment, and the time when it starts to spread

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what does the length of the lag phase depend on

A
  • reproductive life cycle of species
  • how many individuals make up the founder population
  • are there successive waves of introduction?
  • luck
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

step #4 of the invasion process

A

SPREAD
Once the population of an introduced species reaches a critical number, the species will begin to spread rapidly through the novel environment
- at this phase, the introduced species is typically populous enough to be noticed by humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what determines the rate of spread

A

The ability of the species to disperse.

- introduced birds can travel over a greater distance than introduced toads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what happens at the end of the spread phase

A
  • at the end of the spread phase, the introduced species will come to occupy all suitable ecological niches in the novel habitat
  • if those niches already occupied by native species (most likely is) –> conflicts can arise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how long does it take for an introduced species to fill all available niches in the novel habitat

A
  • a very long time

- some argue that an introduced species never truly reaches equilibrium with its environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

step #5 of the invasion process

A

IMPACT
- occurs once the introduced species has spread to the point where it begins to have a negative impact on the environment –> becomes an invasive species
- only invasive species reach the impact phase
(by definition, an introduced species does NOT have a negative impact)
- the impact phase can overlap with the spread phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how do steps in the invasion process act as barriers to invasion

A

Each stage excludes species
- an exotic species may make it past the transport phase, but cannot become established
- an exotic species may become established, but remain in the lag phase and fail to spread
Only a few species are able to survive all stages + successfully become an introduces species in a new environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

do all introduced species become invasive species

A

No, of the the species which successfully become introduced species –> even fewer become invasive species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are “invasive traits”

A
  • are there general traits which are found in all invasive species?
  • can we use these traits to predict which species will become invasive?
  • sometimes yes!
  • invasion potential = the ability of a species to become an invasive species in a novel habitat
  • all attempts to classify species for their invasion potential has failed
  • the presence of these “invasive traits” in an introduced species suggests it may be more likely to become invasive (but no guarantee)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what general traits are associated with greater invasion potential

A
  1. higher fecundity
    - many offspring produced rapidly
    - “propagule pressure”
  2. ability to reproduce asexually
    - especially in plants
  3. being a generalist in habitat preference and food needs
    - can live in a wide range of habitats and eat many different food sources
  4. defensive or hunting strategies not found in the novel environment
    - being poisonous, etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is prey naivete

A

= when a prey species has no defensive response to a predator species
- high local biodiversity can limit the occurrence of prey naivete

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what factors in the novel environment support invasive species survival

A

If a newly introduced species resembles a species already found in the novel habitat:
- prey in novel habitat will recognize the introduced species as predator
- prey naivete is less likely
BUT if an introduced species looks nothing like any established species, prey in the novel environment are unlikely to know how to respond

25
Q

example of prey naivete: albatross vs mice

A

Albatross chicks of gough island
- no evolutionary history with mice
- chick doesn’t understand that mouse are eating them –> causing bird population decline
- the mice are 20% larger on gough island than on the mainland
(“insular gigantism” )

26
Q

what is insular gigantism

A

= biological phenomenon in which the size of an animal isolated on an island increases dramatically in comparison to its mainland relatives)

27
Q

what is predator release

A
  • in many ecosystems, predators help control prey numbers
  • if an introduced species is found in a novel environment where few/ no species hunt it—> numbers can increase exponentially
28
Q

example of predator release: cane toads in australia

A

Cane toads in their native habitat (South America) have many different predators:
- predators are immune to toad poison
- toads are eaten by predators, toad numbers remain stable
But cane toads in their novel environment (Australia):
- all predators die from the toad toxin
- cane toad population is increasing exponential growth

29
Q

how does high biodiversity repel novel invasions?

A

High biodiversity usually indicates available niches are being fully exploited
- harder for a new species to become established and survive past the lag phase if there are no open niches to exploit

30
Q

Invasion potential of a species is a function of:

A
  1. traits of the introduced species

2. characteristics of the novel environment

31
Q

does evolution play a role in invasive species?

A

Introduced species:
- small population cut off from larger origin population –> starts an entirely new population
Many different genetic factors common to small founding populations at work during species invasions

32
Q

Evolution in invasive species - what is the founder effect?

A

Founder effect:
- small founder population has different allele frequencies than larger source population
–> reduced genetic diversity
(genetic bottleneck)

33
Q

what can reduce founder effect?

A

Multiple waves of introduction over time can reduce founder effect:

  • each new introduction = gene flow
  • gene flow = reintroduction of genes from source population to founder population
34
Q

evolution in invasive species- hybrid speciation

A

Introduced species can hybridize with native species
- eliminating both original species and creating a single new hybrid species
“Genetic pollution” = when a native species experience excessive hybridization with an introduced species

35
Q

example of hybrid speciation: mallard ducks

A

Mallard ducks = very common species.
Obvious sexual dimorphism:
- male is bright green
Whenever the pretty green male mallard is introduced, the females choose to selectively breed with them
–> extinction of the native species (such as Hawaiian duck)

36
Q

how does natural selection play a role in invasive species evolution

A
  • not all individuals in a single species could survive the invasion process
  • but those that DO survive are likely to have the best genes for survival in adverse conditions
    (perfect for adapting to an unpredicatable novel environment!)
  • so the invasion process itself likely selects for invasiveness through natural selection
37
Q

how does genetic drift effect evolution in invasive species

A

Once established, very little natural selection may be acting on an introduced species –> genetic drift
Small populations:
- particularly impacted by genetic drift
- every mutation in a small population contributes more to the overall gene pool than it does in a large population

38
Q

what are the effects of invasive species on native species

A

Often results in selection pressure on native species
- ex evolution of prey response
Sometimes native species cannot adapt rapidly enough
- driven to extinction
Some native species adapting
- ex native snake evolving smaller mouths to eat smaller cane toads (smaller toads = less toxin)
Behavior changes in natives species
- australian crow has learned to flip the cane toad on its back (less toxic part of skin)

39
Q

what is invasion meltdown

A

= where an invasive species negatively impacts multiple native species both directly and indirectly by modifying the abiotic environment

40
Q

example of invasion meltdown: Christmas island

A

Christmas Island = home to many endemic crab species.
Crabs fulfill various roles:
- decomposers
- burrowers
- scavengers
The decline of the christmas island crab primarily caused by the yellow crazy ant.
The decline of crabs is now impacting other species:
- leaf litter building up –> loss of borrows for use by other species
- soil no longer mixing
Forest decline is opening up niches for other invasive species
- giant african land snail
Yellow crazy ants spray acid on young birds –> causing deformities

41
Q

intentional introduced species: what are biological controls?

A

Biological control:

  • the intentional introduction of non-native species to control another (usually non-native) species
  • typically, the species to be used as a biological control is a natural predator or parasite of the other species in their native range
42
Q

why doesn’t biological control usually not work?

A

No matter how well a species performs in the controlled conditions of a lab, or how predictably it acts in its native range –> we cannot predict how it will act in a novel environment

43
Q

examples of intentional introduced species for human use

A

Introduced species for human use. Often involves stocking land for alter:

  • stocking a lake with non-native fish
  • releasing goats on an island for later use as food
  • releasing moose to hunt on Newfoundland
44
Q

how can we prevent and control introduced species

A

Human activities:
- primary method of modern species introductions
Human action:
- primary method that we can control both…
1. the spread of introduced species
2. mitigating the impact of invasive species

45
Q

what does the invasion curve tell us?

A
  • most successful –> control an introduced species EARLY or prevent its transport entirely
  • the longer a species is introduced, the more difficult it is to eradicate
46
Q

what is the best strategy for preventing new introduced or invasive species?

A

preventing the transport (first step in invasion process)

47
Q

methods used to prevent transport of non-native species: SHIP BALLAST

A

Ship ballast:

  • ships travelling in freshwater rinse their ballast tanks in salt water
  • ships must empty their ballast water at sea before entering port
48
Q

methods used to prevent transport of non-native species: AIR TRAVEL

A

Air travel:

  • planes often fumigated (dosed with insecticide or pesticide)
  • trained dogs to detect vertebrates
  • water planes must be cleared of aquatic invaders
49
Q

methods used to prevent transport of non-native species: TOURISM & GLOBAL TRADE

A

Tourism:
- tourists can be disinfected
- in New Zealand, your shoes are cleaned and sterilized before you leave the airport
Global trade:
- cargo shipments can be fumigated
- where fumigation is not an option, shipments can be searched by hand

50
Q

why is it difficult to control an introduced species at the ESTABLISHMENT phase?

A

Need to:
- first FIND an introduced species
(very different as new populations tend to only have a few individuals)
- eliminate all individuals in the introduced population)

51
Q

why is it difficult to control an introduced species at the LAG phase?

A

Same issues as the establishment phase:
- how do you find individuals?
- how do you find enough of them to eradicate the entire species
Remember: during the lag phase, like the establishment phase, population numbers are generally too low for us to notice the species

52
Q

why is it difficult to control an introduced species at the SPREAD phase?

A
  • during the spread phase the population density of the introduced species has risen to the point where it is visible in the environment –> no longer difficult to find
  • HOWEVER greater numbers = much more difficult to eradicate
  • at this stage, all we can do is limit spread
53
Q

why is difficult to control an introduced species at the IMPACT phase?

A
  • similar to issues seen in the spread phase, but more severe
  • often impossible to control an invasive species at this number because of sheer numbers
54
Q

what is mega eradication

A

= the complete eradication of one or more invasive species in a novel habitat
Generally only possible on island habitats:
- where invasive species cannot move to a new location

55
Q

does mega eradication work

A

To date, nearly 1000 populations of invasive species have been successfully eradicated from island habitats
- unfortunately not keeping pace with new introductions

56
Q

what is new zealand’s plan for mega eradiaction

A
  • want to eliminate all invasive predators from the island by 2050
  • using poison, trapping, gene drive technology
  • if successful, would be the greatest mega eradication ever undertaken
57
Q

why is new zealand so vulnerable to invasive species

A
  • island nation with naive fauna compared to continents
  • very stable temperate environment
  • many different habitats
58
Q

what is unusual about species invasions in the past and species invasions today

A

The number of species being moved and the timeframe

  • many more species than are typical
  • very short time period (~500 years)

ENVR 202 (18-25) (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions