Exploitation Flashcards
Give an example of top-down and bottom-up control in food webs.
Top-down: wolves in a forest, regulating the population of herbivores (e.g., deer), which in turn affects the plant community.
Bottom-UP: abundance of primary producers (plants) in an ecosystem can influence the population dynamics of herbivores, which then affect predators.
Does fruit and seed predation always have negative consequences on plant fitness?
No many fruits are designed to be eaten which helps with seed dispersion
What is overcompensation?
Overcompensation- plants respond to herbivory by growing back more vigorously than before
Under what circumstances is a predator attack more like a disturbance event than a regular exploitative interaction?
When a predator consumes a large proportion of a plant population, significantly altering the plant community in a short period of time.
what is the role of apical dominance in overcompensation?
Apical dominance- growth of lateral buds, so when herbivores consume the tips of plants, the plant may stimulate growth from other parts, leading to a compensatory increase in biomass.
tolerance in strategies for dealing with herbivory
Tolerance: Reducing the negative impacts of herbivory by rapidly regrowing after being eaten.
Example: Acacia trees that regrow quickly after herbivores consume leaves.
resistance in strategies for dealing with herbivory
Resistance: Traits that reduce herbivore preference or efficiency, such as tough leaves or chemical toxins.
Example: The spines of cacti.
escape in strategies for dealing with herbivory
Escape: Timing growth and reproduction to avoid periods of heavy herbivory.
Example: Winter annual plants that grow when herbivore activity is low.
What is the Red Queen hypothesis and what consequences are predicted for the long-term persistence of species?
Co-evolution is a zero-sum game, where one species’ gain is another’s loss, that eventually go extinct
What limits predation rate at low prey density, what at high prey density?
Low prey density, predators are constrained by the time it takes to capture and digest prey.
At high prey density, the predation rate levels off because the predator is constrained by time to process and consume prey
What are the general outcomes of a predator-prey model, both in terms of the population dynamics that might ensue and in terms of who might go extinct?
Predator Extinction: If predators are inefficient, they may go extinct, and prey may reach carrying capacity.
Boom-Bust Cycles: If predators are too efficient, the populations can oscillate, with prey declining followed by predator declines.
Mutual Extinction: If the predator is too specialized and efficient, both the predator and prey may go extinct.
What is the single largest land form under human use, globally? What is its current status?
grazed grasslands
experiencing overgrazing and degradation
What is the problem with managing a grazing system for maximal profit?
leads to overgrazing
decline of grassland resources
reduces soil fertility,
lower productivity and environmental degradation in the long term
What is overgrazing?
livestock graze an area more than the land can regenerate
What are the tell-tale signs that a range has been overgrazed?
barren patches of land
reduced plant cover
increase in erosion.
What is the tragedy in the tragedy of the commons?
individuals, acting in their self-interest, deplete a shared resource, leading to long-term harm for everyone involved.
What is the basic calculation at the heart of the tragedy of the commons?
each individual benefits from taking more than their fair share, while the cost of depletion is shared by all
What is the only remedy to avert ‘ruin for all’ in terms of human natural resource use or pollution?
effective management and regulation
such as self-governance by communities
clear resource boundaries
collective decision-making
monitoring to prevent overuse.
