Ecology and Population

Question 1

Ecology

Answer 1

the study of the interactions between organisms and their environment.

Question 2

Epidemiology

Answer 2

• branch of medicine
• that deals with the incidence
• distribution
• and possible control of
• diseases and other factors relating to health.

Question 3

population

Answer 3

group of individuals

• of the same single species
• that simultaneously occupy the same general area

Question 4

density of population

Answer 4

number of individuals per unit area

Question 5

dispersion of population

Answer 5

the pattern of spacing between individuals within geographic boundaries.

Question 6

what defines how populations are distributed?

Answer 6

resources

Question 7

clumped dispersion

Answer 7

when individuals aggregate in patches

Question 8

uniform dispersion

Answer 8

when individuals are evenly spaced.

Question 9

random dispersion

Answer 9

the position of individuals is independent of the others.

Question 10

demography

Answer 10

study of factors that affect the growth/ decline of populations

Question 11

main types of graphs in demography

Answer 11

• life tables

- survivorship curves

Question 12

life tables

Answer 12

age-specific summary

-of survival pattern of a population.

Question 13

cohort

Answer 13

group of individuals of the same age

Question 14

best way to construct a life table?

Answer 14

follow a cohort for their whole lives and document it

Question 15

reproductive table

Answer 15

an age specific summary

-of reproductive rates of a population

Question 16

why do demographers usually ignore males?

Answer 16

they can’t give rise to offspring

Question 17

life history

Answer 17

the traits that affect an organism’s schedule of reproduction and survival. caused by natural selection and parallel environmental factors.

Question 18

semelparity

Answer 18

when the organism produces large numbers of offspring during reproduction and then the individual dies afterwards.

Question 19

example of semelparity

Answer 19

agave plant

Question 20

iteroparity

Answer 20

have many reproductive episodes but only produce a few eggs during each one.

Question 21

example of iteroparity

Answer 21

giraffes, humans

Question 22

change in population size during a fixed time interval

Answer 22

number of births during time interval - number of deaths during time interval
N/t = B-D (the squares in this case are meant to be triangles that represent “change in”)

Question 23

ZPG

Answer 23

Zero population growth i.e. Birth rate = death rate

Question 24

Under what conditions does exponential growth in population usually occur?

Answer 24

Unnatural conditions eg. breeding programmes

Question 25

How is population growth regulated?

Answer 25

carrying capacity

Question 26

Carrying capacity

Answer 26

the maximum stable population size an environment can support

Question 27

What does the logistic population growth model do?

Answer 27

takes into account population density and carrying capacity when calculating the rate of increase. K= carrying capacity

dN/dT= rmax N (K-N/K)

Question 28

examples of when the logistic population growth model doesn’t apply

Answer 28

population of song sparrows

Question 29

Density-dependent factors

Answer 29

increase their affect on a population as population density increases. (negative feedback) eg. death rate

Question 30

Density-independent factors

Answer 30

are not affected by population density. No feedback to slow population growth

Question 31

What causes negative feedback?

Answer 31

• limited resources leads to reduction in reproduction
• waste accumulation
• disease (spreads more rapidly in denser populations)

Question 32

examples of erratic population fluctuation

Answer 32

male crabs

Question 33

examples of “boom and bust cycles” (fluctuate greatly)

Answer 33

lynx, snowshoe hare

Question 34

What are some problems facing large populations

Answer 34

• stress on renewable resources
• reduction of nonrenewable resources
• shortage of food
• increased energy requirements

Question 35

When did the rate of growth start slowing down and why?

Answer 35

1960’s

-due to diseases such as AIDS and voluntary population control

Question 36

Why is human population said to be heterogeneous?

Answer 36

Because it is made of smaller populations, each with different characteristics

Question 37

What must be ensured to have population stability?

Answer 37

ZPG
high birth rates - high death rates = ZPG
low birth rates - low death rates = ZPG

Question 38

Demographic transition

Answer 38

The movement from high birth rates- high death rates to low birth rates-low death rates (i.e. each time is ZPG)

Question 39

What is one of the biggest things that leads to demographic transition?

Answer 39

-Reduced family size

due to contraception, social change (delaying having children), family planning etc.

Question 40

What is age structure and what is the benefit of it?

Answer 40

• the relative number of individuals of each age.
• it can predict future growth trends eg. possible diseases, should governments be increasing funding for nursing homes etc.

Question 41

What is the population of the earth predicted to be by 2050?

Answer 41

7.3 to 10.7 billion

Question 42

Ecological Footprint

Answer 42

a measure of the demand on and supply of nature.

Question 43

What are the 6 types of ecologically productive areas that are used when calculating the ecological footprint?

Answer 43

PLOBFF

• Pasture
• Land used for growing crops
• Ocean
• Built up land
• Forestry
• Fossil energy land