chapter 40: population ecology and the distribution of organisms

Question 1

what is ecology?

Answer 1

the scientific study of the interactions between organisms and the environment. these interactions determine organisms distribution and abundance.

Question 2

what is climate?

Answer 2

the long term prevailing weather conditions in an area constitute its climate

Question 3

what are the four major abiotic components of climate?

Answer 3

temperature, precipitation, sunlight, and wind

Question 4

what are abiotic factors?

Answer 4

abiotic factors are the non-living chemical and physical attributes of the environment

Question 5

what are biotic factors?

Answer 5

biotic factors are the other organisms that make up the living component of the environment

Question 6

what are global climate patterns determined by?

Answer 6

they are determined largely by solar energy and the planet’s movement in space

Question 7

what does the warming effect of the sun cause?

Answer 7

the warming effect of the sun causes temperature variations, which drive evaporation and circulation of air and water. this causes latitudinal variations in climate.

Question 8

what are species distributions the result of?

Answer 8

ecological and evolutionary interactions through time.

Question 9

what biotic factors affect the distribution of organisms?

Answer 9

1) predation
2) herbivory
3) mutualism
4) parasitism
5) competition

Question 10

what is predation?

Answer 10

the preying of one animal on others

Question 11

what is herbivory?

Answer 11

the consumption of plant material by animals

Question 12

what abiotic factors affect the distribution of organisms?

Answer 12

1) temperature
2) water and oxygen
3) salinity
4) sunlight
5) rocks and soil
6) physical structure
7) pH
8) mineral composition

Question 13

what is salinity?

Answer 13

amount of salt dissolved in a body of water

Question 14

what is population ecology?

Answer 14

explores how biotic and abiotic factors influence density, distribution, and size populations

Question 15

what is a population?

Answer 15

a group of individuals of a single species living in the same general are. they are described by their boundaries and size.

Question 16

what is dispersal?

Answer 16

the movement of individuals away from centres of high population density or from their area of origin. dispersal contributes to the global distribution of organisms.

Question 17

what is density?

Answer 17

the number of individuals per unit area or volume

Question 18

does canada have a low or high density?

Answer 18

low density

Question 19

what is despersion?

Answer 19

the pattern of spacing among individuals within the boundaries of the population

Question 20

what are the 3 types of dispersion?

Answer 20

1) clumped - for resources
2) uniform - spread out evenly in a specific order
3) random - unlimited resources

Question 21

what is demography?

Answer 21

the study of the vital statistics of a population and how they change over time

Question 22

what is the change in population size formula?

Answer 22

change in population size = births + immigrants entering population - deaths + emigrants leaving population

Question 23

what is the population growth rate formula?

Answer 23

delta N / delta T = B - D

Question 24

what is the per capita growth rate formula?

Answer 24

cgr. = delta N/ N or N(final)-N(final)/ N(initial)

Question 25

what is exponential population growth?

Answer 25

the population increase under idealized conditions

Question 26

what is r max?

Answer 26

under idealized conditions, the rate of increase at its maximum is called r max

Question 27

what is the equation of exponential population growth?

Answer 27

dN/ dT = rmax N

Question 28

what type of curve does exponential population result in?

Answer 28

J shaped curve. it characterizes populations in new environments or rebounding populations

Question 29

what does lag time in a J-shaped curve graph show?

Answer 29

shows that exponential growth is coming. it is seen in populations with no limitations on resources. it is not sustainable, eventually it levels off.

Question 30

what is carrying capacity (K)?

Answer 30

the max. population size the environment can support. it varies with the abundance of limiting resources

Question 31

what is the logistic population growth model?

Answer 31

the per capita rate of increase declines as carrying capacity is reached. it starts with the exponential model and adds an expression that reduces the per capita rate of increase as N approaches K

Question 32

what type of curve does the logistic population growth model give?

Answer 32

sigmoid (s-shaped) curve

Question 33

what ends up having an s-shaped curve?

Answer 33

everything - shows limitations of an area

Question 34

what is a life history?

Answer 34

an organism’s life history comprises the traits that affect its schedule of reproduction and survival

Question 35

what does life history determine?

Answer 35

biotic potential (r)

Question 36

what is biotic potential?

Answer 36

how quickly an organism could produce if there was no limits on it

Question 37

what is K-selection?

Answer 37

selects for life history traits that are sensitive to population density

Question 38

what is R-selection?

Answer 38

selects for life and history traits that maximize reproduction

Question 39

are humans K or R selected species?

Answer 39

K selected

Question 40

what happens to birth rate and death rate in density independent populations?

Answer 40

birth and death rates do not change with population density

Question 41

what happens to birth and death rate in density dependent populations?

Answer 41

birth rates fall and death rates rise with population density

Question 42

what is competition of resources?

Answer 42

occurs in crowded populations; increasing population density intensifies competition for resources and results in lower birth rates

Question 43

what is toxic wastes?

Answer 43

produced by a population can accumulate in the environment, contributing to density-dependent regulation of population size. accumulation decreases population size.

Question 44

what is predation?

Answer 44

predation may increase with increasing population size due to predator preference for abundant prey species.

Question 45

what is territoriality?

Answer 45

territoriality can limit population density when space becomes a limited resource.

Question 46

what is disease in relation to population size?

Answer 46

disease transmission rates may increase with increasing population density.

Question 47

what are intrinsic factors?

Answer 47

physiological factors (ex. hormone changes) appear to regulate population size

Question 48

what is population dynamics?

Answer 48

the study of population dynamics focuses on the complex interactions between biotic and abiotic factors that cause variation in population size.

Question 49

what are bottom up factors?

Answer 49

Bottom up factors are pressures that limit the availability of resources to lower trophic levels (e.g. producers) A lack of resources at lower trophic levels suppresses the abundance of organisms at higher trophic levels.

Question 50

what are top down factors?

Answer 50

Top down factors are pressures applied by a higher trophic level to control the population dynamics of the ecosystem. The top predator either suppresses the abundance of its prey or alters its behaviour to limit its rate of population growth.