Chapter 13 Part 1

Question 1

how do populations fluctuate?

Answer 1

naturally, over time

Question 2

Wild population numbers undergo significant

amounts of variation from year to year

Answer 2

variations
that occur in invertebrates as well as vertebrates ….
in plants as well as bacteria, fungi and even viruses

Question 3

wild population numbers are dependent on

Answer 3

changing environmental conditions over time (weather/climatic conditions) - these factors can influence such things and competitive interactions, predation rates, herbivory, parasitism

Question 4

variation in the density of a population depends on:

Answer 4

1. the amoung of environmental fluctuation (both density dependent and density independent factors)
2. the inherent stability in the population

Question 5

all populations experience fluctuations due to factors such as

Answer 5

availability of resources, predation, competition, disease, parasites, and climate

Question 6

Fluctuations include

Answer 6

random and cyclic changes through time

Question 7

Some populations tend to remain

Answer 7

relatively stable over long periods

Question 8

In contrast, some populations exhibit

Answer 8

much wider fluctuations

Question 9

Small organisms (e.g., algae) tend to reproduce much faster than larger organisms (e.g., red deer), so their populations often respond

Answer 9

faster to favorable and unfavorable conditions (high surface areas)

Question 10

Larger organisms have a lower surface-area-to-volume ratio, which allows them to

Answer 10

maintain homeostasis in the face of unfavorable environmental changes

Question 11

some of the most pronounced population fluctuations in nature are the predictable cycles of certain

Answer 11

mammal and bird species at high latitudes

Question 12

When an age group contains a high or low number of individuals, the population likely experienced

Answer 12

high birth or death rates in the past

Question 13

Long-term fluctuations in age structure can be determined for a forest by

Answer 13

examining tree rings

Question 14

Populations in nature rarely follow a smooth approach to their

Answer 14

carrying capacity

Question 15

overshoot

Answer 15

when a population grows beyond its carrying capacity

Question 16

when does overshoot occur

Answer 16

often when the carrying capacity of a habitat decreases from one year to the next

Question 17

die-off

Answer 17

a substantial decline in density that typically goes well below the carrying capacity

Question 18

when do die-offs often occur

Answer 18

when a population overshoots its carrying capacity

Question 19

Populations With High Growth Rates Track
Environmental Fluctuations More Closely
Than

Answer 19

Those With Low Growth Rates

Question 20

Environmental changes continually increase and
decrease the carrying capacity of the environment
for each population. How a population responds to such
changes through density-dependent effects, depends on …

Answer 20

the intrinsic capacity of the population to increase
in size … that is, its r value (which ultimately is
influenced by the extent to which the species is “r”
or “k” selected)..

Question 21

The faster the potential rate of growth or decline
of the population – i.e., the higher the fecundity and
the shorter the life span of individuals

Answer 21

the greater is
its capacity to track change in its environment (e.g.
r-selected species).

Question 22

Populations with r > 1 tend to

Answer 22

track environmental

changes

Question 23

populations with r < 1 may

be

Answer 23

unresponsive to short-term environmental change

Question 24

A population

with a higher growth rate (r = 0.5) tracks

Answer 24

a population with

a lower growth rate (r = 0.1)

Question 25

Population Cycles May Result From

Answer 25

Intrinsic

Demographic Processes

Question 26

Environmental changes generally tend to be

Answer 26

irregular rather than predictable

Question 27

biological responses to environmental changes are also frequently

Answer 27

random and unpredictable

Question 28

The sizes of many populations do, however,

change with

Answer 28

periodic frequency

Question 29

a number of small mammal cycles have become part of the

Answer 29

lore of population ecology

Question 30

Charles Elton, in 1924, showed that the lynx, and its

main prey, the snowshoe hare, display

Answer 30

large, regular fluctuations in population size - with each cycle lasting about 10 years

Question 31

Fluctuations in population numbers may result in

Answer 31

a time delay

Question 32

Fluctuations in population numbers may result in a

time delay in the response of

Answer 32

births and deaths to changes in the environment - just as the momentum imparted to a pendulum

Question 33

The momentum provided to a population with
high birth rates at low densities or high death
rates at high densities …. results in

Answer 33

the population
“swinging” past its equilibrium point when
demographic responses are time-delayed

Question 34

Times delays are inherent in models based on

Answer 34

discrete generations

Question 35

Population cycles

Answer 35

regular oscillation of a population over a longer period of time

Question 36

Some populations can exhibit

Answer 36

highly regular fluctuations in size

Question 37

Cyclic populations can occur among

Answer 37

related species and across large geographic areas (e.g., the synchronous cycles of the capercaillie, black, and hazel grouses in Finland).