Chapter 36 Population Ecology

Question 1

What is a population?

Answer 1

Group of individuals that belong to a single species that occupies the same geographical area where they can interact

Question 2

What factors decide whether a group of individuals is a population or not?

Answer 2

1. Individuals must consist of the same species
2. They must live in an area where they can interact
3. Mate with one another
4. Affected by the same biotic and abiotic factors
5. Rely on the same resources such as food sources

Question 3

What is the study of population ecology?

Answer 3

Study how populations grow, shrink and respond to environment factors over time

Question 4

How do populations grow?

Answer 4

Birth and immigration (moving in)

Question 5

How do populations shrink?

Answer 5

Deaths and emigration (moving out)

Question 6

What are the two important aspects of a population structure?

Answer 6

1. Population density

2. Dispersion pattern

Question 7

What is population density?

Answer 7

Number of individuals living in a unit area or unit volule

Question 8

What are some examples of population density?

Answer 8

1. Number of oak trees per square kilometer

2. Number of earth worms living in a square meter of soil

Question 9

How is population density measured?

Answer 9

Sampling the population and estimating the density

Question 10

What is population dispersion pattern?

Answer 10

The way the individual organisms of a population are spaced out in the area they live in

Question 11

What are the dispersion patterns?

Answer 11

1. Clumping
2. Uniform dispersion pattern
3. Random dispersion pattern

Question 12

What is clumped dispersion pattern?

Answer 12

Individuals are grouped in patches

Question 13

What usually drives clumping in populations?

Answer 13

Unequal resource availability in the environment of the population. Organisms clump closer to the places where resources are available and plentiful

Question 14

Give an example for clumped dispersion patterns?

Answer 14

Sea stars crowd places where food is plentiful

People crowd cities where employment is plentiful

Question 15

What is Uniform dispersion pattern?

Answer 15

Organisms in a population are dispersed evenly within the environment

Question 16

What drives uniform dispersion pattern?

Answer 16

Interaction between individuals

Question 17

Give some examples for uniform dispersion patterns?

Answer 17

1. Some trees secrete toxic chemicals to prevent other trees of the same species from taking root closer to it so that other trees would not compete for the same resources
2. Territorial behavior of animals. E.g. Lions

Question 18

What is random dispersion pattern?

Answer 18

Organisms are dispersed in an unpredictable way

Question 19

Why is random dispersion rare?

Answer 19

Organisms always react to environment conditions to spread across their environment

Question 20

Give an example for random dispersion pattern?

Answer 20

Dandelions spreading by wind

Question 21

What can you say about the human population growth?

Answer 21

It has been growing exponentially from 1500 to today

Question 22

What is the current estimated human population?

Answer 22

7 billion

Question 23

Why would a population grow?

Answer 23

Birth rate is higher than death rate (or immigration and birth rate is higher than emigration and death rate)

Question 24

Why would a population shrink?

Answer 24

Birth rate

Question 25

What happens when the birth and death rates are equal?

Answer 25

population growth slows down or does not grow at all

Question 26

What is the demographic transition?

Answer 26

Birth rates and death rates that are high but roughly equal to birth rates and death rates that are low and roughly equal

Question 27

What is the age structure of a population?

Answer 27

Number of individuals in different age groups

Question 28

What is the fertility rate of a population?

Answer 28

Average number of children produced by a female over her lifetime

Question 29

What is population momentum?

Answer 29

Rate of increase of number of women of child bearing age