Chapter 53 Population Ecology

Question 1

the study of populations in relation to their environment, including environmental influences on density and distribution, age structure, and population size

Answer 1

population ecology

Question 2

the number of individuals per unit area or volume

Answer 2

density

Question 3

patterns of spacing of individuals within a population

Answer 3

dispersion

Question 4

how can population size be estimated?

Answer 4

• extrapolation from small samples (quadrad method)
• and index of population size (e.g., number of nests)
• the mark-recapture method

Question 5

mark-recapture formula

Answer 5

N=sn/x

N-population size
s-tagged samples
n-second set of samples
x-how many are marked in the second sample

Question 6

scientists capture, tag, and release a random sample of individuals (s) in a population
marked individuals are mixed back into the population
they capture a second sample of individuals (n) and note how many of them are marked (x)

Answer 6

mark-recapture method

Question 7

3 patterns of dispersion

Answer 7

• clumped dispersion
• uniform
• random dispersion

Question 8

• the study of the vital statistics of a population and how they change over time
• death rates and birth rates are of particular interest to demographers

Answer 8

demography I

Question 9

• an age-specific summary of the survival pattern of a population
• it is best made by following the fate of a cohort (a group of individuals of the same age)

Answer 9

life tables

Question 10

a graphic way of representing the data in a life table

Answer 10

survivorship curves

Question 11

what are the three types of survivorship curves?

Answer 11

• type1: low death rates during early and middle life and an increase in death rates among older age groups
• type2: a constant death rate over the organism’s life span
• type 3: high death rates for the young and a lower death rate for survivors (large number of offspring, little to no care to offspring)

Question 12

age-specific summary of the reproductive rates in a population
it describes the reproductive patterns of a population
often concentrate on females in the population

Answer 12

reproductive table or fertility schedule

Question 13

Per Captita rate of increase

Answer 13

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

Question 14

results when population increase is under idealized conditions
growth results in a j-shaped curve
ex: rebounding populations

Answer 14

exponential growth

Question 15

the maximum population size the environment can support

Answer 15

carrying capacity (K)

Question 16

the per capita rate of increase ________ as carrying capacity is reached

Answer 16

declines

Question 17

the ________ of population growth produces a sigmoid (s-shaped) curve

Answer 17

logistic

Question 18

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

• the age at which reproduction begins
• how often the organism reproduces
• how many offspring are produced during each reproductive cycle

Answer 18

life history

are evolutionary outcomes reflected in the development, physiology, and behavior of an organism

Question 19

species that reproduce once and die

ex: salmon and some plants

Answer 19

semelparity or big-bang reproduction

Question 20

species that produce offspring repeatedly

Answer 20

iteroparity

Question 21

organisms have finite resources, which may lead to ________ between survival and reproduction

Answer 21

trade-offs

ex: survival and parental care in European kestrel birds. the more offspring the less chance of survival

Question 22

• when birth and death rates do not change with population density
• selects for life-history traits that are sensitive to population density and favored at higher density*
• operates in populations near the limit imposed by their resources (the carrying capacity, k)

Answer 22

K-selection or density-dependent selection

Question 23

• selects for life history traits that maximize reproduction
• occurs in environments in which population densities that are bellow carrying capacity*, and there is little competition

Answer 23

r-selection or density-independent selection

Question 24

two general questions about regulation of population growth…

Answer 24

• what environmental factors stop a population from growing indefinitely? (carrying capacity)
• why do some populations show radical fluctuations in size over time, while others remain stable?

Question 25

in density-_______ populations, birth rate and death rate do not change with population density
ex: temperature, precipitation

Answer 25

independent

Question 26

In density-_______ populations, birth rates fall and death rates rise with population density
ex: food resources
example of negative feedback that regulates population growth

Answer 26

dependant

Question 27

density-dependent birth and death rates are affected by what factors?

Answer 27

• competition for resources
• toxic wastes
• predation
• intrinsic factors (physiological factors)
• territoriality
• disease

Question 28

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

Answer 28

population dynamics

Question 29

what can influence population dynamics?

Answer 29

• the population of large mammals can fluctuate over time and are not always relatively stable
• weather and predator population can change over time
• some populations undergo regular boom-and-bust cycles

Question 30

a group of Dictyostelium amoebas can emigrate and forage _______ than individual amoebas.

Answer 30

better

Question 31

groups of populations linked by immigration and emigration

-high levels of immigration combined with higher survival can result in greater stability in populations

Answer 31

metapopulations