ap bio - 8.3/8.4

Carry capacity

The sustainable abundance of species that can be supported by an ecosystems total available resources

Density

Number of individuals per unit are or volume

Additions to population

Birth and immigration

Subtracting to population

Death and emigration

Dispersion

Pattern of spacing among individuals within boundaries of population

Clumped dispersion

individuals organized in patches

Uniform dispersion

evenly spaced

Territoriality dispersion

Defense of bounded physical space from other individuals

Random

Unpredicted spacing

Differences in local densities give information about…

Environmental associations and social interactions of individuals

Demography

Study of vital (birth/death rates) statistics and change over time

Type 1 survivorship curve

Low death rates during early life, increase overtime with age

Type 2 survivorship curve

Constant death rate over lifespan

Type 3 survivorship curve

Big death rate early on (bc lots of offspring but no care), then decrease as age increases

Reproductive rates focus on:

Only female babies because they make offspring

Reproductive output

Average number of female offspring for each female in age group

High reproductive rate doesn’t lead to rapid population and survival unless…

Conditions near ideal for growth and survival of offspring

All in a population have the potential to expand when…

Resources are abundant

Unlimited growth doesn’t occur naturally for long because…

There is less access to resources with population increase

Change in population size =

Births + immigrants entering population - deaths - emigrants leaving population

Delta

Change

N

Population size

T

Time

B

Number of births

D

Number of deaths

R

Number of individuals added to or subtracted from population during given time; difference between birth and death

R=

B-D ; dn/dt

Intrinsic rate of increase

Per capita rate at which exponentially growing population increase in size at each instant in time; J shaped curve

Higher intrinsic rates grow…

Faster

Logistic growth rate

Rate of population growth approaches zero as population size nears carrying capacity

Populations adjust instantaneously to growth and approach carrying capacity smoothly

Graph evens smoothly

Density independent

Birth rate or death rate doesn’t change with population density

Density depenendent

Death rate increase or birth rate falls with population density