A pattern of population growth where organisms reproduce continuously at a constant rate (yeast cells)

Geometric Growth

A pattern of population growth where organisms reproduce at fixed intervals at a constant rate (white tailed deer)

A population of 2500 yeast cells in a culture tube is growing exponentially. If the intrinsic growth rate

r

is 0.030 per hour, calculate the initial instantaneous growth rate of the population

**Characteristics of Population**

**Growth**

Example

dN/dt = rmaxN x [(k-N)]/k

dN/dt=rN

td=0.69/r

r = 0.030 per hour

n = 2500

dN/dt=rN

= 0.030 x 2500

= 75 per hour

Calculate the time it will take for the population to

double in size

r = 0.030

td = 0.69/r

= 0.69/0.030

= 23 hours

Example

=(N(t+1))/(N(t))

N(t) = n(0)

Example

Logistic Growth

A model of population growth describing growth that levels off as the size of the population approaches its carrying capacity (fur seals)

dN/dt = rmaxN x [(k-N)]/k

Sinusoidal Growth

A pattern of population growth where an increase of reproduction is symmetrical to the decrease of reproduction - common in predator vs prey (foxes and rabbits)

Density

Population Density:

the number of individuals of the same species that occur per unit area or volume

Crude Density:

measured in terms of number of organisms of the same species within the total area of the entire habitat

D = N/S

Ecological Density

Measured in terms of the number of individuals of the same species per unit area or volume actually used by the individuals

D=N/(space total-space unused)

Distribution

Population Distribution:

the arrangement of individuals in a given area

Individuals are usually drawn to favourable living conditions such as adequate precipitation, food supply and healthier atmospheres

Uneven population distribution worldwide

3 types of distribution: clumped, uniform and random

Population Density

vs

Population Distribution

Distribution

Density

how the population is spread across one area

determined by economic, political and social factors

number of people in a certain area

determined by resources, climate and quality of land

Populated Areas

Sparsely Populated:

harsh areas, few people

Example: Antarctica

Carrying Capacity

The maximum number of organisms that can be sustained by available resources over a limited period of time

Factors: food supply, birth/death rates, biotic potential and environmental resistance

Biotic Potential:

the maximum reproductive capacity of a population under optimum environmental conditions

Environmental Resistance:

the resistance presented by the environmental conditions to limit a species from growing out of control or to stop them from reproducing at maximum rate

Humans have not reached carrying capacity because of:

advances in technology

recycling programs

biomeditation

power generating systems (solar cells)

Carrying Capacity of The Earth

The earth can hold up to an estimated 10-15 billion people

Depending on various conditions the maximum and minimum carrying capacity determines the growth of a population

Earth's carrying capacity is predicted by using equations (e.g. logistic equations)

Advanced technology allows the human population to grow to a wide availability of natural resources

rmax

[(k-N)]/k

population size N

population growth rate

0.50 20 980/1000 9.8

0.50 200 800/1000 80

0.50 500 500/1000 125

t

Densely Populated:

many benefits, many people

Example: Europe

Example

Calculate the crude density of a population of painted turtles if 34 turtles were counted in a 200 hectare park

D = N/S

= 34/200

=0.17

Each May, harp seals give birth on pack ice off the coast of Newfoundland. In a hypothetical scenario, an initial population of 2000 seals gives birth to 950 pups, and during the next 12 months, 150 seals die

Year 1, population change = 950 seals - 150 seals

= 800 seals

Initial population N(0) = 2000 seals

Population at end of year 1, N(1) = 2000 + 950 - 150

=(N(t+1))/(N(t)) = 2800/2000 = 1.4

N(t+1) = N(t)

N(2) = 2800 x 1.4

= 3920

Assuming the population is growing geometrically, what will the harp seal population be in two years?

k = 1000 rmax = 0.5