Topic 19 Flashcards
Fitness require
- suitable environment conditions (abiotic factors)
- sufficient resources (acquire energy efficiently and appropriate quantities)
Predation
individual of one species (predator) consumes all or part of a living individual of another species (prey). includes blood feeders (mosquito)
Predation excludes …
decomposers or scavengers
3 predation categories
- herbivory
- carnivory
- parasitism
Herbivory
prey is plant or alga
Carnivory
prey is an animal
Parasitism
for those parasites the feed on host tissue
Carnivorous plants
derive their nutrients but not energy from trapping and digesting prey. 630 species. attract prey species
Active and passive trapping system of carnivorous plants
- snap traps
- bladders
- flypaper
- pitfalls
- lobster pots
4 differences of herbivore and carnivore
- carnivore typically kills their prey, whereas this is not the case as often with herbivore
- animal tissues are higher in nitrogen than plant tissues and so have a higher nutritional value
- animals can hide and plants cannot
- carnivores are often generalists and herbivore are specialists
Specialist
individual takes one or a few prey types
Generalist
individual takes many prey types
Preference
proportion of a prey type in the diet is higher than in the environment
Preferences will depend on
- energy content of prey
- nutritional content of prey
Preferences switches depend on
abundance of different prey types
Prey switching
switching to increased consumption rates of a more abundant type that used to be abundant
Profitability
net energy gained after energy is spent capturing and consuming the prey
Search time
search efficiency for prey
Handling time
time to pursue, subdue and ingest prey
Increased search and handling time both operate to ..
reduce consumption rate of predators
Increased size of population decreases ..
search time and in some cases handling time
Passive and filter feeders functionally have a
handling time of 0
In general consumption rates and prey population size have a ..
linear relationship until satiation
At very low population sizes consumption rates will decrease disproportionally and..
- need to learn capture strategy
- prey switching hasn’t occurred
- refuges exist ** good test question
Goal is to predict the ..
optimal foraging strategy under certain conditions
2 assumptions of optical foraging theory
- foraging behavioural enhances fitness
- animals maximize net energy gain
Foraging strategy
behavioural trait favoured by natural selection in the past
Predators must expand energy too
obtain prey
Energy lost vs energy gain
searching and handling time vs consumption
Diet model for specialist
-energy lost searching (consume more profitable prey)
Diet model for generalist
-consume less profitable prey (low energy searching)
2 diet model strategies have similar ..
net energy gain under different environmental conditions
Diet model predicts that
- search time»_space; handling time =generalist (raccoon)
- if handling time»_space; search time =specialist (lion)
Optimal foraging theory underlying model assumptions
- predators know everything about their foraging environment
- predators perform complex mathematic to determine the profitabilities of a variety of prey types
Model predicts that ..
individuals that approach the optimal strategy will have higher fitness.
Predators may use..
general rules (take less profitable prey type after searching for a fixed amount of time)
Predators may not maximize ..
net energy gain (take less profitable prey type with a specific dietary requirement)
Predators may minimize their own..
risk of predation (take less profitable prey type to avoid foraging near a predator)
Marginal value theorem
- Works off habitat patch concept
- A foraging animal should leave a patch when consumption rates drop below the average for the range
- Giving up time–the point at which consumption rates become average and to maximize energy gain the animal should leave the patch
- Heavily influenced by distance between patches