Nature of Predation Flashcards
Types of predator specializations?
Monophagous, oligophagous, polyphagous, most predators broad in prey
What must be taken into account when analysing pop dynamics?
Animals food access, not just food observed to be eating
What does prey selection depend on?
Integral part of a mixed, balanced diet
Highest nutritional value
Most sustainable to consume
Prey selection for carnivores?
Energy gained per unit of handling time and lessenging chance of damage to self
Optimal Foraging Theory
This says that traits that maximise surplus energy gained per unit time from foraging are selected or an individual
How do OFT assumptions differ with specialists/generalists?
Long tim hunting prey or not, expending energy, however giving up profit in consuming particular prey
OFT in equation form…
E/H > e/(s+h)
Derive OFT equation…
E energy content, H handling time, being diet profitability
What does OFT model indicate?
Predator should continually add less profitable items to their diet, so long as it increases overall rate of energy intake
What does OFT predict?
Inverse proprtionate relationship between handling and search times, predator being generalist when handling time short
What does switch from optimal diet occur?
When different prey occupy different microhabitats and profitabiltiy change with density
Equation for Optimal Foraging Theory…
Ei/Hi > e/(s+h)
Derive OFT equation…
E energy content, H handling time(profitability of diet
What does the OFT equation tell you?
Predator should continually add less profitable items to their diet, so long as energy intake increases
Example of feeding in presence of predators…
Barn Owl affects realised niche/foraging behaviour of heteromyid rodents, who move to microhabitats to where predators not present
What are three categories of plant defense to herbivory?
Deterrancce
Resistance
Tolerance
Production of plant defences…
Anticipating attack or direct response to one
Example of secondary chemical production…
Coupled with reduced growth like oxalic acid and ctanide
Apparency Theory
Classifies plants as apparent, K-strat, and unapparent, R-strat, investing in tannins and secondary chemicals.
Example of production of compounds in presence of predators?
Jasmonates concentrates in important tissues, affecting ants that attack herbivores
How many plants compensate herbivory?
Removal of shaded leaves
Distribution of photosynthate energy stores
Bud stimulation thats otherwise dormant
Herbivory effect on plants…
Young trees face death with tissue degradation by squirrels when cambial tissue and phloem are torn from the xylem
Example of herbivores acting as vectors for disease…
Scolytid beetles feed on twigs of elm trees, vector for DED
Examples of animal defences…
Snails in shells
Mammals in burrows
Threat displays
Monarch Butterflies defence
Predate milkweed containing glycosides that are poisonus to vertebrates
