# Density dependent factors

### Read the case study on page 149.

Cyclic population variation

### Levels on complexity in an ecosystem

Figure 6.1 page 150

Population distributions page 152 figure 6.3.

### POPULATION DENSITY

NUMBER OF INDIVIDUALS/ UNIT OF DEFINED

AREA

Population distributions.

### Limits on population growth

Density dependent factors

Competition, predation, parasitism, infectious disease

Symbiosis is two organisms living in close association with each other. Give an example of a parasite/host relationship.

Density independent factors

Mainly abiotic factors such as floods, hurricanes, fire, pollution.

If a pond freezes over and a heron can not obtain fish, it does not matter how dense the population of fish is in the body of water.

• r rate of population growth

K carrying capacity

• n population

r species; experience

r selection

Time

Carrying capacity

K species; experience

K selection

K

Fig. 5-14, p. 112

Logistic growth

Exponential or geometric growth

### Environmental resistance

Rule of 70 for doubling time

What would be the doubling time for a \$1000 investment with an annual percentage rate of

3%?

### Actual past APES question

If the population of rabbits in an ecosystem grows at approximately 4% per year, the number of years required for the rabbit population to double is closet to a. 4 years b. 8 years c 12 years d 17 years e 25 years

3

The power of exponential growth

A science major is home for vacation and takes a job for thirty days. She tells her employer instead of a wage of \$20.00 per hour (40 hour week) she will take one penny the first day then double it each day for 30 days = 536,870,912

Which person the employer or science major is getting the best deal? Show set up.

### Limits on population growth

Malnutrition-diet does not supply one or more essential vitamins, protein, minerals---or other nutrients.

Undernutrition- not enough food to meet energy requirements.

Rickets--------Vitamin D

Scurvy-----vitamin C

### Patterns

r-Selected species, opportunists p.159

K-selected species, competitors p. 159

For the year 2012 there were 671 births in

Rutherford County. There were four infant deaths. Calculate the infant mortality rate in

Rutherford county for 2012. Show set up. No calculators.

1.

Logistic growth is going to produce a sigmoid curve. What shape is a sigmoid curve?

2

Exponential growth OR geometric growth is going to produce what shape of a curve?

4

The power of exponential growth. II

Under ideal conditions, some bacteria can divide and double their numbers in about 20 min. How many hours would it take for a single bacteria to divide and reach 4096 in a person with an inner ear infection?

No calculators.

5,6

. Name the type of survivorship curve you would expect given the following descriptions of organisms.

5. The organism is an annual plant. ----it lives only one year------is sprouts, reaches maturity, produces many small seeds, and dies.

6. The organism is a mammal. It bears one young every two years. The mother will attack to defend her young.

7

The crude birth rate is the number of live births per _____ persons in a given year.

A. 50

B.

100

C. 500

D. 1,000

E. 100,000

8

The two most useful indicators of overall health in a country or region are

A. birth rate and death rate

B. replacement-level fertility rate and total fertility rate

C. life expectancy and death rate

D. life expectancy and infant mortality rate

E. population growth rate and death rate

9

Countries that have reached zero population growth have an age structure diagram that

A. forms an inverted pyramid

C. shows little variation in population by age

D. has a large pre-reproductive population

E. has a large reproductive population

10

Rapidly growing countries have an age structure diagram that

A. forms an inverted pyramid

C. shows little variation in population by age

D. has a small pre-reproductive population

E. has a large post reproductive population

11

It was estimated that in the United States in the year 1851 that 217,000 babies died between the age of 0 and 1 year old. What was the infant mortality rate?

Currently in North Carolina the infant mortality rate is 8.85.

12

This author wrote An Essay on the Principle of

Population in 1798 in which he hypothesized that a population could grow at such a rate as to outstrip its food supply.