Chapter 53

Question 1

Ecology

Answer 1

the study of how living organisms and the physical environment interact in a complicated web of relationships

Question 2

Abiotic interaction

Answer 2

interactions with the environment

Question 3

Environmental science

Answer 3

focuses on how humans interact with the environment

Question 4

Life is organized into

Answer 4

populations, communities, ecosystems, landscapes, and biosphere

Question 5

population

Answer 5

members of the same species that live together in a specified area at the same time

Question 6

Features that characterize populations

Answer 6

1. Population density
2. population dispersion
3. birth and death rates
4. growth rates
5. survivorship
6. age structure

Question 7

populations share a common

Answer 7

gene pool

Question 8

natural selection acts directly on

Answer 8

allele frequencies to produce adaptive changes in populations

Question 9

Radnom dispersion

Answer 9

occurs when individuals are spaced in a manner that is unrelated to the presence of others (rare)

Question 10

Clumped dispersion

Answer 10

individuals are concentrated in specific parts of the habitat (most common)

Question 11

clumped dispersion results from

Answer 11

patchy distribution of resources in the environment

Question 12

clumped dispersion occurs among animals because of

Answer 12

animals because of the presence of family groups and pairs,

Question 13

Clumped dispersion occurs among plants because of

Answer 13

limited seed dispersal or asexual reproduction

Question 14

when is clumped dispersion advantageous?

Answer 14

when social animals benefit from their association

Question 15

uniform dispersion

Answer 15

when individuals are more evenly spaced than a random pattern

Question 16

uniform dispersion occurs when

Answer 16

animals establish feeding or mating territories

local depletion of resources: shading in forest leads to uniform distribution of trees

Question 17

Growth rate

Answer 17

rate of change of a population on a per capita basis

it is the birth rate minus the death rate

Question 18

natality

Answer 18

of individuals added to the population through reproduction over a particular time period

Question 19

mortality

Answer 19

of deaths in a population over a particular time period

Question 20

sex ratio

Answer 20

relative # of males and females in a population

Question 21

age distribution

Answer 21

number of individuals of each age in the population

Question 22

exponential population growth

Answer 22

a plot of population size versus time has a J shape characteristic

Question 23

at or near the limits of the environment to support the population

Answer 23

population growth rate may decrease to nearly zero

Question 24

environmental limits

Answer 24

availability of food, water, shelter

essential resources

limits imposed by disease and predation

Question 25

Carrying capacity

Answer 25

the capacity that the environment can carry in nature, carrying capacity is dynamic and changes in response to environmental changes

Question 26

logistic population growth

Answer 26

a population regulated by environmental limits over longer periods displays an S-shaped curve initial exponential increase is followed by a leveling out as carrying capacity of the environment is approached

Question 27

factors influencing population size

Answer 27

density dependent and density independent

Question 28

density dependent factors

Answer 28

if a change in population density alters how an environmental factor affects that population effects of these factors increase as the population density increases

Question 29

Density dependent factors list

Answer 29

1. Predation 2. Disease 3. Competition

Question 30

Density independent factors

Answer 30

any environmental factor that affects the size of a population but is not influenced by changes in population density

Question 31

Density-independent factors are typically

Answer 31

abiotic, such as random weather events

Question 32

large organisms are usually affected by

Answer 32

density-dependent factors

Question 33

small organisms are usually affected by

Answer 33

density-independent factors

Question 34

Semelparous

Answer 34

species that expend their energy in a single, great reproductive effort

Question 35

Iteroparous species

Answer 35

exhibit repeated reproductive cycle throughout their lifetime

Question 36

Iteroparous breeding most common in

Answer 36

most vertebrates, perennial herbaceous plants, shrubs, and trees

Question 37

survivorship

Answer 37

the probability that a given individual in a population or cohort will survive to a particular age

Question 38

How is survivorship plotted?

Answer 38

logarithm of the number of surviving individuals against age, from birth to the maximum age reached by any individual

Question 39

Type 1 survivorship

Answer 39

decreases more rapidly with increasing age; mortality is greatest later in life (humans)

Question 40

type 2 survivorship

Answer 40

does not change with age; death is equally likely across all age groups (rare)

Question 41

Type 3 survivorship

Answer 41

increases with increasing age; young are most likely to die

Question 42

total fertility rate

Answer 42

the average number of children that would be born to a woman over her lifetime

Question 43

age structure

Answer 43

the number and proportion of people at each age in a population

Question 44

age structure diagram

Answer 44

represents the number of males and females at each age, from birth to death

Question 45

for less developed countries

Answer 45

the age structure diagram is shaped like a pyramid

Question 46

for highly developed countries

Answer 46

age structure diagrams have more tapered bases - smaller proportion of population is prereproductive

Question 47

diagram of a stable population shows approximately the

Answer 47

same number of people at prereproductive and reproductive ages

Question 48

in a population that is shrinking the

Answer 48

prereproductive age group is smaller than either reproductive or postreproductive group