lec 10- predation

Question 1

what are the examples of structural defenses of plants against herbivory?

Answer 1

spines, thorns, defensive hairs

Question 2

what are the two types of chemical defenses a plant can have?

Answer 2

generalized inhibition-tannins reduce availability of plant proteins to consumers, inhibit digestion
specific inhibition- interfere with a specific animals physiology, palatability is reduced

Question 3

why are chillies hot?

Answer 3

due to capsaicin

Question 4

what are the good herbivores and bad herbivores of the chilli plants?

Answer 4

good herbivores- birds, they aren’t affected by the capsaicin and like to spread seeds around
bad herbivores- rodents, they grind the seeds and dont spread them, capsaicin works on them

Question 5

what are the two ways defenses are turned on?

Answer 5

constitutive defenses- always at high levels (tannin in oak leaves)
induced defenses- turned “on” by herbivore damage

Question 6

what is the optimal foraging theory?

Answer 6

-a formal framework with which to make predictions about foraging behaviour of predators
-nearly all consumers have multiple types of prey
-each prey has benefits and costs
-benefits are energy density and nutrients
-costs are energy to digest, handling time, travel time danger etc.
-profitability of each prey type can be ranked in terms of their relative cost: benefit ratio
-abundant prey meaning predators will look for most beneficial prey, low numbers means less profitable and more opportunistic

Question 7

which is more common:
optimal or opportunistic feeding

Answer 7

opportunistic feeding

Question 8

do predator and prey relationships oscillate?

Answer 8

yes

Question 9

what formula is used to see predator prey relationship?

Answer 9

dR/dt = rR - cRP

R = prey
P = predator
r = growth rate
c = capture efficiency

Question 10

what are the three predation components?

Answer 10

1. searching for prey
2. attacking prey
3. handling and digesting prey
   -more prey means less time to search for them

Question 11

what factors helps predators and prey have an oscillating relationship?

Answer 11

immigration/aggregation- highly mobile predators
reproduction/population growth- lags behind changes in prey abundance

Question 12

why dont most predator prey relationships cycle?

Answer 12

because there are many factors that stabalize them, such as:
-predator inefficiency
-density dependence of predators or prey
-alternative food sources for predator
-refuges for prey
-reduced time delays in predator response to prey dynamics