2 slides

population structure

grouping a population into specific parts rather than treating everyone the same

age structure

grouping by age

stage structure

grouping by phase (developmental)

survivorship

probability that an individual survives from one time step/age class

fecundity

avg. # of offspring per female

life table

shows survival, mortality, reproduction rates for e/a group

F: fecundity
P: persistence (contributes to growth rate; survive and remain in population)
G: graduating

transition matrix

uses life table to predict how a population changes annually

life table formula

n_t+1 = Ln_t

n_t+1: each stage @ next step (future)
L: rates for e/a life phase
n_t: current

transition matrix formula

n_t+1 = λn_t

n_t+1: each stage @ next step (future)
λ: annual growth multiplier
n_t: current

Best management strategy

• Increasing survival in large juveniles, subadults, adults = positive population growth

• type III survivorship curve

Exploitation

• One species benefits, one species harmed (+ / -)

• Consists: predation, herbivory, parasitism

Competition

Both harmed (- / -)

Mutualism

Both benefit (+ / +)

Predation

• Animals eating animals

• Kill prey immediately (will eat many prey per lifetime)

Predation (Prey)

• Cannot tolerate predation

  • Resist/avoid predation (fleeing)

Herbivory

• Herbivores tend not to kill the plants they eat immediately

• 1 herbivore could spend its whole life eating one individual plant

Herbivory (Prey)

• tolerate herbivory (maintain fitness despite losing biomass to herbivores)
  − resist herbivory (deterrence, toxicity)
  − avoid herbivory (grow when or where herbivores are scarce)

Consumptive

• Direct

• Predator directly kills + eats prey

Non-Consumptive

• Indirect

• Change prey behavior, reduce foraging + reproduction (mental affects)

Outcomes of Predator-Prey Interactions

Both went extinct, predator only extinction, coexistence

Factors leading to coexistence

• Prey refuges

• Reduced predation efficiency (barriers to slow)

• Resource limitation on prey (carrying capacity or food availability)

• Immigration

What is the difference between observational data, a “natural” experiment, a lab experiment, and a field experiment? Which of the data sets from today come from each type?

1. Lab (mites on oranges)- researchers manipulate variables in controlled laboratory setting to see what happens

2. Observational (Lynx-Hare trapping records)- watch and record what happens in nature without changing anything

3. Field (Lynx-Hare enclosure)- Researchers manipulate variables outdoors in a natural habitat

4. Natural (Wolf-Elk)- Researchers study a natural even to compare populations before and after