apes unit 3

Question 1

r-selected - “quantity”

Answer 1

Many offspring, little to no parental
care

May reproduce only once, but
generally reproduce many times
throughout lifespan

Ex: insects, fish, plants

Shorter lifespan, quick to sexual
maturity = high biotic potential = high
population growth rate

More likely to be invasive

Better suited for rapidly changing
environmental conditions

Question 2

K-selected - “quality”

Answer 2

Few offspring, heavy parental
care to protect them

Generally have fewer
reproductive events than
r-strategists

Ex: most mammals, birds

Long lifespan, long time to
sexual maturity = low biotic
potential = slow population
growth rate

More likely to be disrupted
by environmental change or
invasive species

Question 3

k selected usually live in habitats…

Answer 3

Usually live in habitats with
higher competition for resources

Populations that reach carrying
capacity (K) usually remain at
stable size, near K

Hence, K-selected or
K-strategist

Question 4

r selected usually live in habitats….

Answer 4

Usually live in habitats with lower
competition for resources

Population are more likely to fluctuate
above and below carrying capacity
(overshoot and die-off)

“r” is the variable used to
represent maximum reproductive
rate in ecology

Hence, r-selected or r-strategist

Question 5

Type 1(K selected)

Answer 5

High survivorship early in life
due to high parental care

High survivorship in mid life due
to large size & defensive
behavior

Rapid decrease in survivorship in
late life as old age sets in

Ex: humans

Question 6

Type 2 (between K and R selected)

Answer 6

Steadily decreasing survivorship

Question 7

Type 3 (mostly r-selected)

Answer 7

High mortality (low survivorship)
early in life due to little to no parental
care

Few make it to midlife; slow, steady
decline in survivorship in mid life

Even fewer make it to adulthood; slow
decline in survivorship in old age

Ex: insects, fish, plants

Question 8

Carrying Capacity (K):

Answer 8

the max. Number
of individuals in a pop. that an ecosystem can
support (based on limiting resources)

Question 9

Overshoot:

Answer 9

when a population briefly
exceeds carrying capacity

Ex: deer breed in fall, give birth all at
once in spring; sudden spike in pop. =
overshoot

Question 10

Consequence of overshoot:

Answer 10

resource
depletion ex: overgrazing in deer

Question 11

Die-off Example

Answer 11

Reindeer of St. Paul Island

25 introduced in 1910

Growth was gradual (10’-30’),
then exponential (30’-37’)

Carrying capacity was
overshot

Sharp die-off lead to pop. crash
as food resource (lichen) were
severely depleted

Real pops. don’t always fluctuate
around carrying capacity. If resource
depletion is severe enough, total pop.
crash can occur

Question 11

Die-off:

Answer 11

sharp decrease in pop. size
when resource depletion
(overshoot) leads to many
individuals dying

Ex: many deer starve with too
many new fawns feeding in
spring

Question 12

Predator-Prey example

Answer 12

Hare pop. increase due to
low predator pop. (lynx)

Lynx pop. increase due to
increase in food (hare)

Increasing lynx pop.
limits hare pop; leads to
die-off

Hare die-off decreases
lynx food source, leading
to die-off

Hare pop. increase due to
low predator pop. (lynx)

Question 13

Size (N):

Answer 13

total # of individuals in a given
area at a given time

Larger = safer from population decline

Question 14

Density:

Answer 14

of individuals/area

Ex: (12 panthers/km2)

High density = higher competition,
possibility for disease outbreak,
possibility of depleting food source

Question 15

Distribution:

Answer 15

how individuals in population
are spaced out compared to each other

Random (trees)

Uniform (territorial animals)

Clumped (herd/group animals)

Question 16

Sex Ratio:

Answer 16

ratio of males to females.
Closer to 50:50, the more ideal for
breeding (usually)

Die-off or bottleneck effect can lead
to skewed sex ratio (not enough
females) limiting pop. growth

Question 17

Density-Dependent Factors:

Answer 17

factors that
influence population growth based on
size:

Ex: food, competition for habitat,
water, light, even disease

All of these things limit pop. growth
based on their size; aka - small pop.
don’t experience these, large do

Question 18

Density-Independent Factors:

Answer 18

factors that influence population
growth independent of their size

Ex: natural disasters (flood,
hurricane, tornado, fire)

It doesn’t matter how big or
small a pop. is, natural
disasters limit them both

Question 19

Ex. of Density-Dependent Factor

Answer 19

Food is a density dependent factor.
(also a limiting resource)

When twice as much food was
added to the dish, both species
increased carrying capacity
by about 2x

Question 20

Biotic potential

Answer 20

= exponential
growth (like a /)

Question 21

Logistic growth

Answer 21

= initial rapid
growth, then
limiting factors
limit pop. to K ( like in precalc)

Question 22

intrinsic rate of
increase

Answer 22

maximum potential growth rate, with
no limiting resources

Question 23

Calculating Population Change

Answer 23

Population Size = (Immigrations + births) - (immigrations + deaths)

Ex: An elk pop. of 52 elk has 19 births and 6 deaths in a season, and 5
new elk immigrate to the herd and 0 elk emigrate from the herd

(19+5) - (6+0) = +18 elk

52 + 18 = 70 elk

Question 24

Total Fertility Rate (TFR):

Answer 24

avg.
number of children a woman in a
population will bear throughout her
lifetime

Higher TFR = higher birth rate,
higher pop. growth rate (generally)

Question 25

Replacement Level Fertility:

Answer 25

the TFR
required to offset deaths in a pop. and
keep pop. size stable

About 2.1 in developed countries
(replace mom & dad)

Higher than 2.1 in less developed
countries due to higher infant

Question 26

Infant Mortality Rate (IMR):

Answer 26

1 year per 1,000 people in a pop.

Higher in less developed
countries due to lack of access
to: health care, clean water,
enough food

Higher IMR = higher TFR, due to
families having replacement
children

Question 27

Malthusian theory (what Malthus theorized):

Answer 27

Earth has a human carrying capacity, probably based on
food production

Human population growth is happening faster than
growth of food production

Humans will reach a carrying capacity limited by food

Question 28

Technological Advancement

Answer 28

Humans can alter earth’s carrying capacity with tech.
Innovation

Ex: synthetic fixation of Nitrogen in 1918 leads to
synthetic fertilizer, dramatically increasing food
supply

Question 29

Crude Birth Rate & Crude Death Rate (CBR & CDR)

Answer 29

Births & deaths per 1,000 people in a population

Ex: Global CBR = 20 & CDR = 8

Question 30

Rule of 70:

Answer 30

The time it takes (in years) for a population to double is equal
to 70 divided by the growth rate

Ex: Global growth rate = 1.2%

70/1.2 = 58.3 years

Global pop. will double in 58.3
years

Question 30

Calculating growth

Answer 30

(cbr - cdr) / 10 = growth rate %

Question 31

Industrialization:

Answer 31

the process of
economic and social transition from an
agrarian (farming) economy to an
industrial one (manufacturing based)

Question 32

Pre-industrialized/Less developed

Answer 32

A country that has not yet made
the agrarian to industrial transition

Typically very poor (low GDP)

Typically high death rate & high
infant mortality

High TFR for replacement children
& agricultural labor

Question 33

Industrializing/developing

Answer 33

part way through this
transition

Decreasing death rate & IMR

Rising GDP

Question 34

Industrialized/developed:

Answer 34

completed the transition

Very low CDR & IMR

Very High GDP

Low TFR