C4- Population Biology

Sections 1, 2

Pp. 90-109

S1- Population Dynamics

MAKE foldable p. 91A. Principles of Population Growth

1. How fast? Resembles j-shaped curve Fig 4.2 when exponential or unlimited.2. Limits- Availability of food, disease, predators, lack of space (S-shaped)3. Carrying Capacity- number of org environment can support indefinitely

Population curves

B. Reproduction Patterns

Life history

1. Rapid- reproduce rapidly, produce many offspring in short period of time

Ex. Mosquitoes

B. Reproduction Patterns

Life history

1. Rapid-common among org from changeable env

b. Small size & short life span

C. Pop increase rapidly then decline when conditions unsuitable

B. Reproduction Patterns

2. Slow-rate of repro produce few offspring over long lifetime. Ex. Elephant

a. Stable environmt

b. Mature slowly but long-lived

c. Maintain pop at or nr carrying capacity

B. Reproduction Patterns

3. Density Factors

b. Density-independent- affects pop regardless of density Ex. Abiotic factors-volcanic eruptions, temp, storms, floods, drought, pesticide, habitat disruption

C. Organism Interactions Limit Population Size

1. Predation between populations

2. Competition within population

a. for food, water, & territory

When pop low, resources build up;

When pop increases so demand exceeds supply, then pop size decreases

b. Effects of crowding & stress include:

C. Organism Interactions Limit Population Size

b. Effects of crowding & stress include:

aggression, decrease in parental care, decreased fertility & decreased resistance to disease

C. Organism Interactions Limit Population Size

b. Effects of crowding & stress include:

aggression, decrease in parental care, decreased fertility & decreased resistance to disease

4.2 Human Population

A. World Population- Demography- study of human pop size, density & distribution, movement, birth & death rates.

Demography 1. Growth rate affected by disease

eradication, food production methods, tech developments.

a. Birthrate- no. of live births per 1000 pop in a given year

b. Death rate- no. of deaths per 1000 pop in a given year

c. immigration

d. emigration(Birthrate +Immigration rate) – (Death rate+

Emigration rate) = Pop Growth Rate (PGR)

Demography

2. Effect of Positive Growth Rate- unless growth rate becomes negative, pop continues to grow

Demography

3. Doubling Time- time needed for pop to double

a. Developed Country has SLOW DT

b. Developing Country has RAPID DT

<http://zebu.uoregon.edu/2003/es202/jcurve.jpg>

4. Age Structure- Proportions of pop in different age levels

4.Age Structure Graph

Tells males & females at each age level Stable- percentages are fairly equal Rapid growth- Wide base of youth in

graph.

4. Age Structure- Proportions of pop in different age levels

5 Ecology and Growth

What do populations need?

a. Uncontaminated water

b. Adequate Sewage facilities

c. Ability to provide food

d. Maintaining healthy conditions by controlling disease

Population Needs

India on the Ganges River above; Young and old populations have different needs.