Ch. 11 Lecture

Question 1

Populations can grow _____ when conditions are favorable, but this growth cannot continue _____.

Answer 1

populations can grow EXPONENTIALLY when conditions are favorable, but this growth cannot continue INDEFINITELY.

Question 2

Human population reached ___ in 2016, more than double the population in ___.

Answer 2

Human population reached 7.3 BILLION in 2016, more than double the population in 1970.

Question 3

From _______ human population _____ in size, and energy consumption increased _______.

Answer 3

From 1860 TO 1991 human population QUADRUPLED in size, and energy consumption increased 93-FOLD.

Question 4

Human population reached 1 billion for the first time in ___.

Answer 4

Human population reached 1 billion for the first time in 1825.

Question 5

Human population adds ____ people every ____.

Answer 5

Human population adds 1 BILLION people every 13 YEARS.

Question 6

In 1975, the population was growing at an ________ of ____. At this rate, a population will ____ in size every ___. If this growth rate were sustained, we would reach ______.

Answer 6

In 1975, the population was growing at an ANNUAL RATE of NEARLY 2%. At this rate, a population will DOUBLE in size every 35 YEARS. If this growth rater were sustained, we would reach 32 BILLION BY 2080.

Question 7

Geometric Growth

Answer 7

When a population reproduces in SYNCHRONY at regular TIME INTERVALS (discrete time periods), and growth rate remains the same. The population increases by a CONSTANT PROPORTION, so the number of individuals added to the population becomes larger with each time period.

Question 8

Geometric Growth: graph

Answer 8

J-shaped set of points, straight line when on log scale

Question 9

Exponential Growth

Answer 9

When a population reproduces CONTINUOUSLY, and GENERATIONS can OVERLAP. These populations increase by a CONSTANT PROPORTION.

Question 10

Exponential Growth: graph

Answer 10

J-shaped curve, straight line when on log scale

Question 11

lambda=1 or r=0

Answer 11

population stays the same

Question 12

lambda<1 or r<0

Answer 12

population size will decrease

Question 13

lambda>1 or r>0

Answer 13

population grows geometrically or exponentially. ideal conditions.

Question 14

Why don’t populations expand infinitely?

Answer 14

1. run out of resources
2. other species consume their resources
3. disturbances happen

Question 15

Resources

Answer 15

features of the environment that are in SHORT SUPPLY that are required for growth, survival, or reproduction, and which can be CONSUMED to the point of DEPLETION.

Question 16

Physical Factors

Answer 16

affect population growth rates but are NOT consumed or depleted (i.e. temp, wind, pH)

Question 17

Density-Independent Factors

Answer 17

factors that are not dependent on density.

-floods, fires, drought, irregular growth bursts, hurricanes

Question 18

Density-Dependent Factors

Answer 18

cause birth rates, death rates, and dispersal rates to change as the density of the population changes.

density ^ = birth rates v = death rates ^ = emigration ^ = population size v

Question 19

Population Regulation

Answer 19

occurs when density-dependent factors cause populations to increase when density is low and decrease when density is high.

-food, space, or other essential resources in short supply, then population size decreases.

Question 20

Allee Effects

Answer 20

population growth rate decreases as population density decreases; individuals have difficulty finding mates at low population densities.

“extinction vortex”.

• american passenger pigeon
• northern right whales
• shearwaters

Question 21

Logistic Growth

Answer 21

population increases rapidly at first, then stabilizes at the carrying capacity, because resources such as food, water, or space begin to run short.

Question 22

Carrying Capacity

Answer 22

maximum population size that can be supported indefinitely by the environment. growth rate=0, so population size does not change.

Question 23

Logistic Growth: graph

Answer 23

S-shaped curve in natural population

Question 24

Populations show “boom and bust” dynamics: r- or k-selected species?

Answer 24

r-selected species

Question 25

Populations exist at carrying capacity: r- or k-selected species?

Answer 25

k-selected species

Question 26

Environments which benefit r-selected species

Answer 26

Highly disturbed environments

Question 27

Environments which benefit k-selected species

Answer 27

Stable environments

Question 28

Environments where r-selected species may evolve to k-selected species (poison arrow frogs)

Answer 28

Highly Stable environments

Question 29

What will limit human populations?

Answer 29

(RODS-FLY)

• Resources
• Overgrazing
• Disease
• Sahel region
• Firewood and deforestation
• Loss of top soil
• Your ecological footprint

Question 30

Geometric Growth: equation

Answer 30

N_t+1=lambdaN_t

OR

N_t=lambda^tN₀

Question 31

lambda

Answer 31

geometric growth rate; (per capita) finite rate of increase

Question 32

Exponential Growth: equation

Answer 32

dN/dt=rN

dN/dt: rate of change in population

r: exponential population growth rate; (per capita) intrinsic rate of increase

Question 33

relationship between lambda and r

Answer 33

lambda=e^r

r=ln(lambda)

Question 34

Logistic Growth: equation

Answer 34

dN/dt=rN(1-(N/K))

OR

dN/dt=rN(K-N/K)

N: population density

r: per capita growth rate

K: carrying capacity