population Ecology

Population ecology is the study of ____________________ interactions- organism/s interacting

with member/s of the ____________ species in relation to their __________________; how both

biotic and abiotic factors affect ___________, distribution, size, and age structure of populations.

Density is the _____________ of individuals per unit area or volume (e.g. the number

of _____ trees per square kilometer in Troy). Dispersion is the pattern of ______________

among individuals within the population.

To measure density, population ecologists can:

A) _______________ individuals; can also count nests, burrows, tracks, or _________.

B) _____________ sampling– e.g. count the number of oak trees in several __________

located 100 m x 100 m plots in Troy and calculate an average for the city.

C) __________-______________ method (also called capture-recapture method)- Take

a sample from the population, mark those individuals and release them back into the

population. After the individuals have mixed freely with unmarked individuals, take new

samples, and record the ratio of marked to un-marked individuals.

1st catch X 2

nd catch total

Number of recaptures in 2nd

catch

Q: Approximately how many oak trees

are in this 100 m x 100 m plot? Note:

each sample quadrant is 10 x 10 meters

(100 square meters).

Q: Using this technique, how can you

get a more accurate approximation?

10,000

square

meters

Q: Label the factors in this image that can

increase or decrease population density.

Q: Aside from immigration and emigration,

what else causes a population to grow or

decline?

Populations ↑ when births ____ deaths;

populations ↓ when births ____ deaths.

There are 3 types of dispersion for populations.

______________________ ______________________ ______________________

(Most common) (Most rare)

Demography- studies vital _________________ of populations and how they change over time.

Demographers use _________ tables- age-specific summaries of the survival pattern of a

population which tracks ________________ (individuals of the same age) from birth to death.

The data from a life table is then put into a _______________________ curve.

Q: According to the life table, which gender of ground squirrels has a shorter life expectancy?

Q: The 3 general types of survivorship curves are shown on the right above. Which survivorship curve type

has high death rates early in life due to large numbers of offspring, but little or no parental care?

Q: Which survivorship curve type has a constant death rate over the organism’s life span?

Q: Do most species exhibit a Type I, Type II, or Type III survivorship curve or something in between these

types?

_______________________ table is based on female cohorts producing offspring from birth

to death.

___________________ time- the amount of time between the birth of an individual and the

birth of their ______________________/ offspring. Small organisms typically have _________

generation times (e.g. some bacteria can divide asexually by _____________ fission every _____

minutes), while large organisms typically have longer generation times (e.g. giant coastal

_______________ trees are the __________________ trees in the world, up to 378 feet tall with

a base up to 22 feet in diameter, and do not reproduce until they are _______ years old; the same

is true for giant inland ____________________ trees which are one of the _________________

trees in the world [Montezuma Cypress and African Baobab trees are wider], up to 311 feet tall

with a base up to 40 feet in diameter).

Q: At what age do ground squirrels start having offspring?

Q: At what age range is reproductive output at its peak for

ground squirrels?

Q: How many days on average are many female squirrel

species fertile each year?

Q: Humans have menstrual cycles (shed the endometrial

lining) when not pregnant. What cycle do squirrels and most

other mammals have that reabsorbs the endometrial lining

when not pregnant?

Q: Most mammals (excluding humans) have a bone in the

penis to aid in copulation (mating). What is this called?

20 minutes = 2

40 minutes = _______

80 minutes = _______

120 minutes = _______

Q: While some bacteria can reproduce this quickly, what are some limiting factors that affect their colony

size?

Limited _______________ (food, water, nutrients, energy, & space), toxic ____________ accumulation,

____________________, and ______________ that infect bacteria (called ________________________).

Q: Based on this image of a bacteriophage. What are the two things a virus

must minimally have?

population growth (also called geometric population growth)- a

population whose members all have access to abundant ___________________ and reproduce

without limits. This produces a ____-shaped curve.

population growth- a population with ___________ resources

(limiting factors such as: energy, shelter, refuge from predators, nutrient availability, water, and

suitable nesting sites) that cause a population to reach a ________________ / leveling off point

as the population increases. This produces an ____-shaped curve or sigmoid curve.

There are 2 types of reproductive efforts an organism can make: ______________________ (a

single, large reproductive effort) and ______________________ (repeated reproduction).

Q: Which population is growing faster exponentially?

Q: When does exponential growth occur?

When a population is introduced into a ______ environment,

after a catastrophic event (e.g. a fire destroys a forest), or in a

_______________ situation (_______________ = “in glass”).

A B

Q: What is the name of the plateau in a logistic growth curve?

Q: What letter do population ecologists use to represent the carry capacity?

Q: Circle on the logistic growth curve the inflection point (where the acceleration switches from positive

to negative).

Q: The Daphnia water flea graph is a more realistic depiction of a logistic growth curve. How does it

differ from the first graph’s “S-shaped curve”?

Q: These 2 pictures show an agave (Agave

americana) plant which grows in desert

climates and send up its large flowering

stalk to produce seeds and die. What type

of reproduction is this?

Q: Fermented agave (Agave tequilana)

produces what alcoholic drink?

Life ____________________- (do not confuse this with a “life table” used to create a

survivorship curve)______________ that affect an organism’s schedule of reproduction and

survival. Life histories include: A) when reproduction _____________, B) how often an

organism reproduces, and C) how ____________ offspring per reproductive episode.

r-selected- reproductive success in ___________________ (density-independent) environments

(e.g. weeds growing in a large field). K-selected- reproductive success in __________________

(density-dependent) environments (e.g. African savanna elephants).

Life History Chart r-selected (r = per capita rate of increase)

K-selected (K = carrying capacity)

Maturation Time Life Span Death Rate of Offspring Brood size (# of offspring) # of Reproductions Per Lifetime Timing of the First Reproduction Parental Care Size of the Offspring

There is a “trade off” between reproduction and __________________ survival.

Q: Are petunias annual (live for one growing season) or

perennial plants (longer lives, come back each year,

invest energy into roots and freeze resistant buds)? What

type of reproductive effort do petunias have?

Q: Are roses annual or perennial plants? What type of

reproductive effort do roses have?

Q: Is an r-selected or K-selected life history associated with logistic population growth?

Q: Is an r-selected or K-selected life history associated with exponential population growth?

Q: Are most organisms r-selected, K-selected, or somewhere between these two types?

Q: A normal clutch size (# of baby birds) for this bird species is 5

chicks. The researchers transferred chicks among nests to see the

effects of larger and smaller clutch sizes on parental survival the

following winter. What can you conclude about this bird species?

___________ offspring = _____________ lifespan for parents.

Q: Why is this the case?

________ offspring = more _______________ invested in

reproduction and ________________ of the offspring. Energy

beyond what is used for maintenance and growth of the parents.

The “principle of __________________” states an organism only has limited ______________

so if it uses energy for one function (e.g. reproduction) it will have less energy for other

functions (e.g. its own growth).

Most organisms “allocate” their energy by mating during a breeding __________________

(e.g. Canada geese mate in March).

Density-____________________- factors that affect populations as the number of individuals

____ / the population becomes more “dense”. Density-____________________- factors that

affect population size ____________________ of the number of individuals (e.g. weather or

climate related events such as a _________________, a _______________, cold weather, etc).

Density-Dependent Effects Will the factor increase or decrease as

the population density increases? Parasites

Reproduction / Birth rates

Nutrient Availability

Diseases

Food Availability

Toxic Wastes

Territoriality

Smaller Body Size of Organisms

Competition

Monet keeps complaining that his garden flowers are not as

large as he would hope for in creating his paintings. What can he

do to produce larger, healthier plants in his garden?

__________ the plants out and ________ (trim) them regularly.

Q: The “Black Death” / Bubonic plague (Greek root

word bubo, “swollen gland”) originated in China, but

spread throughout Europe in the 14th century and killed

~75 million people. Is this a density-dependent or

density-independent factor?

Q: Bubonic plague was caused by a bacterium. What

organism was the vector transmitting the bacterium to

humans?

Q: The plague caused death of epithelial (skin) tissue

due to blood not flowing to the skin. What is death of

tissue called?

Q: Which children’s nursery rhyme is now linked to

the plague (despite being written long before)?

Q: Monarch butterflies normally live ~2 months. Those born

at the end of summer need to migrate south to warmer

climates so they live 7+ months. They partition / “allocate”

their energy by entering a non-reproductive phase until

spring. What is this phase called?

Q: Name 3 animals who copulate regardless of the season / not necessarily for the purpose of fertilization.

Some populations of organisms fluctuate in density with regular ___________-and-

____________ cycles (e.g. __________________ insects which have cycles in ____ to ____

years depending upon the species that emerge from the ground at once).

The global human population is no longer growing _____________________, but it is still

increasing rapidly.

Q: The classic example of a “boom-and-bust” cycle is the snowshoe

hare and lynx population of Canada and Alaska. Approximately

how long is this cycle?

Q: What is the cause of the hare population cycling? A

combination of:

#1) Food supply ______ in winter.

#2) Other predators (aside from lynx) eat hares.

#3) ____________ activity- when this is low, less ________ / O3 is

produced so more ____ radiation reaches Earth. Plants respond by

instead of making chemicals to deter _______________, they make

chemicals to block UV light so this ____ the hares food supply.

Q: What is the cause of the lynx population cycling? Is this a

density-dependent or density-independent factor?

Lynx feed almost _______________ on the hares. This is a

density-____________________ example.

Q: How often is the population census taken?

Q: Approximately how many people are there currently

worldwide?

Q: Which country has the most people (~1.3 billion)?

Q: Which country has the second most people (~1.2

billion)?

Q: What are the exoskeletons of

cicadas made of?

Q: How rare is a blue-eyed cicada?

- the relative number of individuals of each age in the

population. This is graphed into age-structure ________________________.

Ecological __________________- the land and water required by each person, city, or nation to

produce all the _______________ it consumes and to absorb all the _____________ it generates.

One benchmark established by ecologists is that the planet can sustain ___ hectares (1 ha = 2.47

acres) per person. A typical American uses about ___ ha, which is ________________________

for Earth’s resources.

Q: The human population skyrocketed after the

Industrial Revolution (~1760-1830) and slowed in

1962. What happened that year?

Q: What is causing the human population to depart

from true exponential growth?

__________________ (including AIDS) and

________________ population control.

Q: Which age structure pyramid has lots of young people who will most likely grow up and sustain

explosive growth with their own reproduction?

Q: Explain the bulge in the United States age structure pyramid.

Q: What is the current reproductive rate in the U.S. per female?

Q: Why is Italy projected to have no growth in their population?

The pyramid has a _________ base (people younger than reproductive age are underrepresented in the

population).

Q: By looking at the US and Italy’s age structure pyramids, which gender tends to live longer?

Q: Why do people in industrialized nations live longer lives?

Better quality ___________ care, _____________________, and improved access to

____________________ (especially for women).

Q: What limiting factors could lead to the Earth reaching

its carrying capacity?

___________ (malnutrition and famine).

#2) Sustainable _________________.

#3) Running out of resources (nonrenewable_________ and

fossil fuels and renewable fresh _______).

#4) Environment unable to absorb its waste.