Quiz 4 Flashcards
Which of the following does the Parker et al. (2006) paper support?
Biotic resistance hypothesis
How did the authors test their questions in this paper?
All answers are correct
Created experimental plots
Observational data
A meta-analysis
A meta-analysis
Which of the following did the authors find in this study?
Exotic plants facilitated invasion by exotic herbivores.
Exotic herbivores facilitated invasion by exotic plants.
Native plants facilitated invasion by exotic herbivores.
Native herbivores facilitated invasion by exotic plants.
Exotic herbivores facilitated invasion by exotic plants.
What is the overarching question addressed in Parker et al.?
Do native/non-native herbivores facilitate/resist invasion by non-native plants?
Describe the research approach did Parker et al. take to address the question?
The authors did a meta-analysis, which means that they examined 63 published studies that experimentally
exclude herbivores. These studies included a broad range of taxonomic groups. They then evaluated how
native/non-native herbivores affected the relative abundance of exotic and native plants
Q: Which types of herbivores are more likely to be associated with ‘enemy release’?
A: Specialist herbivores, because they are evolved to overcome plant defenses, so release from them would be advantageous.
Q: Were invertebrate or vertebrate herbivores more strongly associated with plant effects in Parker et al.’s study?
A: Vertebrate herbivores had stronger effects because they are larger, more mobile, generalist feeders, and more likely to kill rather than suppress host plants.
Q: How do the authors explain the high contribution of European natives to non-native communities on other continents?
A: Land alterations and the replacement of large native herbivores with domesticated ones in Europe allowed native plants to evolve resistance. European plants and domesticated animals were spread worldwide, with domesticated animals helping to facilitate the invasion of European plants.
A reaction-diffusion equation models the change in population size as a function of what? (select all that are correct)
Population growth rate at a location
Dispersal into the location
None of the answers are correct
You Answered
Dispersal out of the location
Population growth rate at a location
Dispersal into the location
What does Skellam’s model predict about population spread?
Spread is constant over time
Spread decreases over time
Spread increases over time
Spread is constant over time
What is a possible reason why spread of an invasive species is faster than predicted by Skellam’s model and reaction-diffusion equations? (select all that are correct)
Passive dispersal by ocean currents
Anthropogenic vectoring
Biotic vectoring (i.e., dispersal by flight, walking, running, swimming)
Thin-tailed dispersal kernel
Anthropogenic vectoring
Biotic vectoring (i.e., dispersal by flight, walking, running, swimming)
Q: What is the reaction-diffusion model in relation to species spread?
A: It mathematically characterizes dispersal as a combination of population growth (reaction) and dispersal (diffusion), where diffusion describes the movement of individuals away from their origin.
Q: What is the significance of long-distance dispersal in the reaction-diffusion model?
A: Long-distance dispersal, like Levy walks or flights, leads to a “fat-tailed” dispersal distribution, which causes higher-than-expected spread rates compared to normal (Gaussian) distributions.
Q: What is stratified dispersal?
A: A dispersal mode that combines short-distance, continuous dispersal with long-distance, jump dispersal, increasing the overall spread rate of invasive species
Q: What is temporal heterogeneity in the context of species spread?
A: Variation in environmental conditions over time, which generally reduces the long-term spread rate of invasive species unless the invasion direction opposes the prevailing conditions (e.g., marine organisms against water currents).
LOOK AT The reaction-diffusion model (this is a partial differential equation) Define the 3 parts to that equation, where the 3 parts are i) the term to the left of the
equals sign, ii) the term that starts with ‘D’, and iii) the term ‘rN’.
i) The change in population size over time in a certain location
ii) The diffusion term, which tells us the number of dispersers coming into
the certain location as a function of the distance to that location.
iii) The location population growth term.
If the population changed over unit time equals 10, and the local population growth rate
equals 8, then how many individuals dispersed into the local population?
10 = X + 8, so X = 2
What is the equation for Skellam’s model and define each term?
𝑐 = √4𝑟𝐷
r is the population growth rate
D is the diffusion term
c is the predicted constant rate of range expansion (spread)
The reaction-diffusion model and Skellam’s model measure two different (but related) things.
What is the distinction?
The reaction-diffusion model measures the growth and diffusion of a population over space.
Skellam’s model is based on the reaction-diffusion model, but it measures the rate of range
expansion (spread) of a population.
Skellam’s model underestimates the rate of range expansion by the gypsy moth (which is now
called the ‘spongy moth’). What is an explanation for this discrepancy (tell both the ecological
details and the general concept)?
Skellam’s model underestimates the spread of the spongy moth because it doesn’t account for its multiple dispersal methods. Female moths can’t fly, so they move very little. However, first-instar larvae disperse by ballooning, using wind to travel up to 1 km or more. Additionally, the moth lays eggs on items like firewood and vehicles, which are moved long distances by humans (anthropogenic vectoring). These two dispersal methods with different patterns, called “stratified diffusion,” create a fat-tailed distribution, leading to faster range expansion than the model predicts.
What does the shape of a dispersal kernel tell you about the ability of Skellam’s model to predict range expansion of a species?
normal, thin tail, fat tail
When the dispersal kernel has a normal distribution, Skellam’s model is a good predictor of range expansion.
When the dispersal kernel has a thin-tailed distribution (fewer long-distance dispersers), Skellam’s model overestimates range expansion.
When the dispersal kernel has a fat-tailed distribution, Skellam’s model underestimates range expansion.
How do dispersal kernels differ among different modes of dispersal and how does that affect predictions by Skellam’s model?
Ocean currents
Wind dispersal (seeds)
Biotic vectors
Anthropogenic vectors (human transport)
Ocean currents (marine organisms) have a thin-tailed distribution, causing Skellam’s model to overestimate range expansion.
Wind dispersal (seeds) has a normal distribution, so Skellam’s model is a good predictor.
Biotic vectors (active dispersal by animals) have a fat-tailed distribution, so Skellam’s model underestimates range expansion.
Anthropogenic vectors (human transport) have a very fat-tailed distribution, causing Skellam’s model to greatly underestimate range expansion.
What was Carey’s alternative hypothesis regarding invasion of the Mediterranean fruit fly in California?
The fruit fly was persisting at densities that were below detection levels for long periods of time.
The fruit flies were intentionally introduced into California.
The fruit flies were successfully eradicated multiple times.
The fruit flies were introduced into California multiple times.
The fruit fly was persisting at densities that were below detection levels for long periods of time.
