Predator vs. Prey

Predator vs. Prey • prey impacts predator population more

hunters kill 500,000 deer/year

predators switch prey instead of starve

Act. 1 – lynx and hareAct. 2 – pike and perch

Population density/distribution (14.3, pgs. 436-439)

population density – how many organisms live in a defined area

clumpeddispersion

uniformdispersion

randomdispersion

population dispersion –

how the population is spread out


clumped – for mating, protection, or food spotuniform – territory and food competition


clumped

uniform


Type I – big mammals (black bear)• few young (1-3), lots of care

Type II – small mammals, birds, rabbits• more young (4-12), less care

Type III – insects, parasites• thousands of young, no care


Population growth patterns (14.4, pgs. 440-444)

Factors that affect populations:1. immigration – species moving in

2. emigration – species moving out

3. birth rate – goes up when habitat is good

4. death rate – goes down when habitat is good


exponential growth – rapid population growth due to abundant resources (pennies)

J-curve

Australia: 24 were brought in 1859 for sport hunting, but enough food, and no good predators = 200-300 million today


logistic growth – slow growth, then exponential growth, then level off due to resource limits

S - curve


carrying capacity - average # supported by an ecosystem; environment quality can change capacity

population crash - dramatic decline• when above carrying capacity• weather related possibly• fire• new species that messes things up


limiting factors – factors that keep population down

1. density-dependent factors: are affected by the population of individuals; when above capacity• competition, predation, parasitism and disease,

starvation

2. density-independent factors: not related to population; can happen anytime

• unusual weather, natural disasters, human activity

Documents

Predator vs. Prey