Invasion Biology Exam

how do cryptogenic species impact how we quantify numbers of introduced species in an area

o If we don't know anything about them (ie range) we don't know if they've been introduced to the area

5 synonyms for invasive species

non-native, non-indigenous, exotic, alien, non-endemic

What is a stable isotope?

non-radioactive form of an atom that has different number of neutrons (same number of protons = same identity, also same electrons)

3 reasons why a species may be cryptogenic

not sufficient research, unknown range, newly described

define lag-time

time it takes for a species to go from introduced to invasive. It's the time we have to easily fix the invasive problem.

· What are your thoughts about the incorporation of ecosystem services in invasion biology? What are your thoughts regarding this scenario: non-native species are increasing some key ecosystem services but are having negative effects on biodiversity?

you have to way the pros and cons of the situation. If it has negative effects on biodiversity (and species are at risk of extinction / endemic to one area) then it isn't worth it. But, if the effects on biodiversity are not severe and it offers key ecosystem services, then the benefits outweigh the cons!

If you are having lunch with your friend and they have the audacity to say: "I don't think invasive species are a problem", how would you respond? Provide examples of economic, biodiversity and ecosystem functioning considerations in your answer

- Cost a lot of money to remove / have economic impacts o Kudzu vines break power lines, cover anything in its path, including houses - Reduce biodiversity o Argentine ants outcompete and destroy native ant colonies, simplifying the diversity in the area = less seed transport = ecosystem changes - Alter ecosystem functioning o Crazy ants spray formic acid at native crabs, physically destroying them. These crabs are responsible for being the top predator in the area, meaning now everything plant-wise can grow uncontrolled.

If some asks you why it is hard to determine if a species is likely to become invasive, how would you answer? Give two examples to support your response.

- Not all invasive species share traits. - Relativity of traits. o Example: timeframe of growing. Mustards are faster than most annuals, whereas invasive pines only develop quickly in relation to other pines - Need to consider traits at all three levels: introduced, established, and invasive. o We are only thinking about invasive species, but what about the other 90% of established species that aren't invasive? o What about those that were introduced, never established, or never invasive

How does enemy release hypothesis differ from EICA? (2 differences)

1. EICA is focused on genetics of the invasive VS enemy release has to do with being novel in area 2. EICA has to do with competition with species in area VS enemy release has to do with if things are coming for you as a resource

list three yes or no questions that should be associated with any risk assessment system regardless of the taxa that are being screened

1. Is this species already established within the area? 2. Is it known to cause harm? 3. Is it a host for pests/pathogens?

2 levels where propagule pressure matters

1. introduction to establishment. number of individuals matters 2. once you're established and spreading

2 predictions of the enemy release hypothesis

1. invasive species will be successful in an area where its former enemies are not present 2. invasive species will do better in a new area because it does not have enemies

3 characteristics associated with good risk assessment system

1. objective (anyone can perform it) 2. time and cost efficient 3. accessible and transparent

2 conclusions of Daehler et al paper on lag times from Lyon Arboretum in Hawaii

1. plants have a much shorter lag time than was thought when measuring indirect data 2. Difference between tropical and temperate lag times, tropical is shorter 3. In order to test a lag time, need date of introduction and follow trajectory. Not good enough to use random dates through time to test it. Need direct not indirect data

Using the terms "extinction" and "population" in your answer, explain how Tiberg et al.'s findings influence your thoughts on how an invasive species may influence regional biodiversity.

Argentine ants influence native ant populations. As local populations go extinct, there is lower ant diversity across the region.

what is the parable of Green Mountain

Ascension Island was a sparse volcanic island, less than a million years old. It was barren according to Darwin. Later, many non-native plants were introduced to the island and planted intentionally. They trapped water and changed the ecosystem by changing weather patterns. The plants stored more carbon. The island now houses a military base, meaning it is inhabitable. By introducing non-native plants, the ecosystem services of the island were increased, allowing humans to live on the island. This is a parable, or moral story we can learn from.

How does parable of Green Mountain change view of invasions?

Introduced species were in this case of large benefit. While it was not a biological invasion per se, it does show that introductions can be beneficial and should not be completely discounted

How does ecological fitting influence your thinking about non-native species and their potential role in systems outside their native range?

It shows that non-native species can have roles in systems outside of their native ranges. The issue becomes when these species are dominant, leading to invasion and danger to other natives. It is important to consider ecological fitting when trying to introduce species counters to invasive species, such as natural pest control.

What is a better approach to examining EICA?

Now, you look at the native vs invasive range seeds alone and with competitor species from those areas. This allows more realistic growth patterns to emerge and see how competition affects things (more real)

Define HHS/green world hypothesis

Predators are very important because they keep herbivores down, allowing plants to grow. For above example: coyotes keep bunnies down, lets plants grow. [To test: get rid of top predator. Hard to do exclusions on big habitats]

How does risk assessment differ from a listing process

Risk assessment can be applied to any new species that enters an area. It is impossible to list all of the potentially invasive species to CA, but it is possible to use information we have to assess each individual species as it may arrive.

Using the paper examining characteristics of pine invasions, did they find that r-, k- or both r- and k-selected species can become invasive? Explain your answer.

Theory says in general r selected species are most likely to be invasive. The paper on pine invasions proves that yes, in general, this is true. However, in other contexts, like squirrel environments, K selected species can become invasive. The difficulty is as ecological context changes, the traits can change too to predict invasion. Not going to be the same across the globe. Environmental context matters!

· Carr et al. demonstrated that propagule pressure was the most important factor in determining abundance an invasive star thistle, yet is seemed to be declining in abundance before the addition of gofers. Explain how you view the influence of propagule pressure in comparison to disturbance.

Seems that early stages of establishment disturbance can have an effect but later once established propagule pressure comes to the forefront While it was suggested that disturbance by gopher should help invasion success, here it was not the main driver of the invasive thistle. Rather, propagule pressure is the most important mechanism

What attributes of the data set helped them specifically test for lag-times and compare how their approach differed from the approach of most other researchers who study lag times.

The attributes that helped: they specifically knew when seeds were grown for the first time, which gives an exact date of when they arrived to Hawaii. It is otherwise very difficult to know how long it's been, then you can only use indirect data which has been shown by this paper to not be as accurate.

What did Maron et al find when examining the introduction of foxes on the Aleutian Islands? Is this an example of a trophic cascade or green world hypothesis?

They introduced randomly some foxes to the Aleutian Islands that have similar plants, soil, climate, and rainfall. Find that foxes eat birds, birds eat fish off the coasts, and then birds have nutritious poops on the islands=nutrients. However, they do not think this is HHS, they think this is a trophic cascade. Does not show green world bc not herbivores consuming plants directly, but rather birds providing nutrient subsidies to the plants. Their influence on the plants is the nutrient subsidies, not direct interaction of herbivory Green world needs direct interactions of predator eating herbivore, which allows more plants to grow By reducing bird numbers, the foxes are getting rid of the fertilizer so the subsidies are not there. yes trophic cascade bc effects 2 levels down, but not directly so not green world

how does ecological fitting contrast other ideas regarding how complex species-rich systems are constructed

This contrasts with the theory that complex-species rich systems are constructed solely by evolution within a region over a large time frame.

How does understanding the potential of invasional meltdown change your opinion on how to manage biological invasions AND protect native species?

Understanding invasion meltdown really highlights the importance of management when an established species begins to become invasive. Invasion meltdown multiplies the effects of invasions by allowing other invasive species to "win" also.

introduced species

a species introduced to a new region, brought to new area by humans

cryptogenic species

a species that we don't know is native or non-native

Why study invasion fronts?

allow you to know how quickly invasion is progressing, get reads of before and after data

Why did Tilberg et al study invasion fronts?

allowed them to understand species loss by Argentine ants, how quickly it progressed. Also find that isotopes are going down at invasion front, meaning Argentine ants are eating lower trophic levels (plants instead of other insects). This trophic flexibility means its easier to persist in novel environments

Invasive species

an introduced species that becomes established/widespread with negative impacts

How are stable isotopes used in trophic ecology?

assess patterns of isotopes to know who's eating where on the food chain. Plants measure at 2, herbivores at 5, predators at 8. Omnivores between 5-8. As we eat we accumulate more of the heavy isotopes. We analyze changes in N15 parts per thousand

4 examples of invasion control costs

control of more frequent wildfires from invasive grasses, control of exotic aquatic weed hydrilla to keep lake recreation in FL, rat control on farms (eat a lot of grains), limiting populations of pigeons (vectors for many diseases, acid poop etc)

Explain how understanding differences between the vectors and pathways can provide information critical to developing effective management strategies

difference is critical for management. We need to know what is bringing invasive to an area (vector) and where they are coming from/going to to stop that flow (pathway)

Explain how you view the influence of propagule pressure in comparison to disturbance.

disturbance facilitates invasion, but level of invasion is dependent on propagule pressure, ie how many individuals are in an area. This affects rate of invasion also.

what does EICA stand for

evolution of increased competitive ability

characteristics associated with successful invasive species

high number of offspring, short time to reproductive maturity, broad niche, high dispersal rate

What is Straw Person argument?

highlighting one aspect of an argument as the main topic of the argument so when it is proven wrong everything seems wrong Example: so-called invasive species increase species richness and biodiversity Also, prop up good invasive species like honeybee and wheat Over time this is false, invasive species reduce biodiversity Also, we aren't trying to get rid of all invasive species, there's a gray area, we just don't want species entering without regulation

How was EICA historically tested? What were the limitations of this approach

historically, EICA was measured considering biomass alone. You would grow seeds from both ranges (same plant) and see how they grew/if they grew differently. This does not account for real life conditions, such as competition

how does lag-time influence how you view and manage invasions?

if few individuals arrive and aren't going to spread for a while we have time to get rid of them and solve the problem. Also important to know if species do have lag times to know when/how quickly to act/the urgency of the problem

3 mechanisms that may cause lag time

initial conditions, arrival of mutualist species, climate conditions change

Explain pathways and vectors associated with internet trade

internet makes things more difficult because it's harder to pinpoint where the supply is from. Regulation is also hard, don't know if things are still being sent despite laws

define ecological fitting

introducing species that did not coevolve in an ecosystem to a system where they can live (suitable climates, niches, etc)

provide an example of invasion meltdown

invasion of crazy ants facilitated the growth and further spread of invasive scale insects, which produce honeydew and mold on plants, which decreases photosynthesis. Also affected top predator, the crab, on the island, who usually control plant numbers

define invasion meltdown

invasive species cause big issues for a food web. The introduction and spread of one invasive species facilitates the establishment and spread of other invasives.

Describe EICA hypothesis

invasive species have more competitive ability in their invasive range than in their native range

Explain how scale of study may influence understanding regarding establishment and spread of invasive species

it's hard to tell fully on small, experimental scale. Invasion paradox shows us how things can be different

which taxa are more likely to be cryptogenic

non charismatic, small species

Define trophic cascade

one animal influences abundance of another and that in turn influences the next. This Animal must influence at least 2 levels below it (Ex. coyotes in California. Eat raccoons, cats, rabbits. Cats eat birds. So, at field station, coyotes keep cats down = bird safety)

2 benefits of using risk assessment system over a listing process

overall, flexibility 1. applicable to any organism (does not have to be listed) 2. can have different ways to be enough of a threat not to get in (depends on threshold)

r vs k selected species

r selected species: -rapid growth -good dispersal -short lifespan (low survivorship, high fecundity) -rarely maintain stable population (ie rarely reach K) -influenced by density independent factors K selected species: -K refers to carrying capacity -Slow growth -long lifespan (high survivorship, low fecundity) -more likely to maintain K -influenced by density dependent factors

What are the 4 categories of ecosystem services

regulating, provisioning, cultural supporting

Define the Enemy Release Hypothesis

success of invasive species is due to it being novel enough in an area that parasites, diseases, and predators don't recognize it as a resource

define ecosystem service

the benefits humans gain from ecosystems (water retention, carbon sequestration, timber, recreation, etc)

propagule pressure

the frequency of introductions and quantity of organisms introduced to a site. Number of colonizing individuals

define invasion paradox

to understand factors determining invasion success we do small-scale experiments. however, in same scale, it seems as diversity increases invasion success decreases. In real life, with random sampling, you find the opposite. invasion success increases in high diversity areas compared to low in real world.

From Hasaka et al (bait worms) what was the vector and what was the pathway

vector: live bait boxes (not seaweed or worms themselves, the whole package) pathway: route of the bait boxes to destination in shops

Describe the difference between a pathway and a vector in invasion biology

vector: mechanism being used to transport non-native species pathway: how that vector gets from point A to B

Explain why it is important for land mangers to be aware of the invasion paradox

you could be fining the complete opposite results on the small scale and really need to analyze on the landscape scale to understand what is going on in your managed land.