POPULATION DYNAMICSChapter 8 pp 197-202

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All the members of a species living in the same place at the same time and breed with each other

May show GENETIC DIVERSITY

A school of glass fish in the Red Sea The field mice living in a corn field Monarch butterflies clustered in a tree Palm trees on a tropical island

POPULATIONS

GENETIC DIVERSITY

PROPERTIES of a POPULATION

SIZE- the number of individuals

DENSITY- the number /area

DISPERSION-relative distribution

AGE STRUCTURE- proportion in different age groups

POPULATION DYNAMICS

Studies the interaction of these characteristics of a population with their environmental conditions

POPULATION SIZE

INCREASES 1- more births 2- immigration

DECREASES 1- more deaths 2- emigration

POPULATION DENSITY

DENSITY DEPENDENT

Factors that effect the population due to how crowded they are, ex:

DiseaseFinding a mate/food/shelterPredationHuman harvesting

DENSITY INDEPENDENT

Factors that effect a population that do not depend on how crowded they are, ex:

Severe weatherNatural disasterHabitat destruction

POPULATION DISPERSION

CLUMPS/PATCHES- most populations live in groups or patches, ex:

desert vegetation near a spring

a wolf pack flocks of birds

Why CLUMPING?

1- gather near their resources

2- easier to find food in a group

3- protection from predators

4- helps predators get food

5- help in finding a mate/care for young

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SOME SPECIES MAINTAIN A FAIRLY CONSTANT DISTANCE BETWEEN INDIVIDUALS ,ex: creosote bushes

A fairly rare method of dispersion where individuals are spread out with no definite pattern

AGE STRUCTURE

The proportion of individuals at various ages

Used to predict future growth of the population

HOW DOES A POPULATION GROW?

CHANGE IN POPULATION =

( Birth Rate + Immigration) -

( Death Rate + Emigration)

Growth Rate

Positive (+) if BR/IMM > DR/EM

Zero (0) if BR/IMM = DR/EM

Negative (-) if BR/IMM < DR/EM

How fast can a POPULATION GROW ?

BIOTIC ( reproductive) POTENTIAL -the fastest rate at which a population

can grow- Each individual has the maximum

number of offspring possible- - depends on reproductive pattern of

individual

BIOTIC POTENTIAL

ELEPHANTS- one offspring every 2 years

In 750 years there will be 19 million elephants

BACTERIA- double in minutes

In a few days or weeks there will be 19 million bacteria

Sea Turtles vs. Songbirds p 199

Why don’t populations reach their biotic potential?

Environmental factors restrict unlimited population growth , ex:

Food Mates Living space/habitat

Exponential growth- J Curve

CARRYING CAPACITY

The maximum population the ecosystem can support indefinitely

Levels off May change

seasonally Tempered by

environmental resistance (LF)

Logistic Growth- S curve

Are Humans exempt from population control? We control our

environment :

TECHNOLOGYFOOD PRODUCTIONMEDICINEIMPROVED SANITATIONEDUCATION

Irish potato Famine

Bubonic Plague

AIDS

Genocide

Math Practice p 201

Math Practice p 201YEAR 1 2 3 4 5 6

Starting pop

100

Births 10

Deaths 5

Ending pop

Growth rate

% change

Math Practice p 201YEAR 1 2 3 4 5 6

Starting pop

100 105

Births 10 20

Deaths 5 10

Ending pop

105

Growth rate

+5

% change

5%

Math Practice p 201YEAR 1 2 3 4 5 6

Starting pop

100 105 115 130 150 175

Births 10 20 30 40 50 60

Deaths 5 10 15 20 25 30

Ending pop

105 115 130 150 175 205

Growth rate

+5 +10 +15 +20 +25 +30

% change

5% 9.5% 13% 15.4% 16.7% 17.1%

Homework : Reindeer POP