Population Ecology

Ecology importance

Insight into 

• Outbreaks

• The health of a specific population

• Sustainable levels of harvest

Population ecology

How and why a population changes over time

A population must

• Be from the same species

• occupy the same area

• rely on the same resorces

• influences by the same environment

• interact and breed with each other

Population size

(N)

Population density

• (D)

• Decreases with increasing body size

  • increases size increased resources needed

Exponential growth

• Due to unlimited recources

  • J-shaped curve

Mathematically conditions for population growth

B > D

• Absolute # of births > Absolute # of deaths

Per Capita

• “Per individual”

• B/N = b

• D/N = d

• b-d=r (per capital growth rate)

Conditions for maximal growth rate

r(max)

• population must live in ideal conditions

Carrying capacity

(K) = the highest N that an environment can support

• Logistical growth

• r reaches 0

Logistical per capita growth rate

• rN [K-N/K]

• The population growth most rapidly when N= K/2

• r will increase exponentially until N approaches K

• When N=K r=0 and N will never change

Why does population growth slow as N approaches K

• D increases

• Causes intraspecific competition for limited resources

Tpes of density dependet population regulation

• Intraspecific competition (Between same species)

• Predator prey population regulation

Types of density independent limitations

Abiotic events ( natural disasters)

Dispersion patterns

Uniform: Penguins and plants (competition for resources)

Random: when resources are evenly distributed

Clumped: the most common.

• Form around resources, for protection, reproduction, hunting.

Generation Time

The mean amount of time between the birth aof an organism and the birth of its offspring