POPULATION DYNAMICS….7billion & Counting

Essential Questions

What are the factors that affect population growth?

What are some of the effects that overpopulation can have on an environment?

http://en.wikipedia.org/wiki/Paul_R._Ehrlich#mediaviewer/File:2008_Summer_Olympics_torch_relay,_Shenzen.jpgSteve JervestonCC BY 2.0

LEVELS OF ORGANIZATIONsmallest unit of living thingsgroup of similar cells organized to work together

group of different kinds of tissues working together

group of organs working togetherone individual living thingall organisms of the same kind living in one area

all interacting populations in an ecosystem

all living and nonliving things interacting within a certain area

large region with characteristic plants and animals that includes several ecosystems

cell

Population

Dynam

ics

Populations in Ecosystems Vocabulary

• Abiotic Factors – Non-living components of an area (rocks, weather, sunlight, etc.).

• Biotic Factors – Living organisms as well as the products of living organisms.

• Carrying Capacity – The maximum size of a population that can be sustained by any given ecosystem.

• Ecosystem – Living and non-living factors interacting within a specific area.

• Organism – A living thing.

Populations in Ecosystems Vocabulary

• Environment – The area around an organism including living and nonliving things.

• Limiting Factor – Any biotic or abiotic factor that controls population size.

• Population – All of the interacting individuals of one species in a given area.

• Birth Rate – Number of individuals born per 1000 individuals in a population.

• Death Rate – Number of individuals that died per 1000 individuals in a population.

Population Dynamics

How populations change in size over time – four major factors

Birth Rate:(number of live births per 1000

individuals)

How can the birth rate

affect population

size?

Death Rate (number of

deaths per 1000 individuals)

How can the death rate

affect population

size?

Immigration: (movement into

an area)

How can immigration

affect population

size?

Emigration:(movement out

of an area)

How can emigration

affect population

size?

Population Size

What goes up must come down

•Increases in population: through birth or immigration

•Decreases in population: through death or emigration.

Change in Population =

Birth Rate +

Immigration

- Death Rate +

Emigration

Logistic or Exponential Growth Curve?

“Boom and Bust” “Boom then Stable”

Can you think of something in nature that exhibits exponential growth? Logistic growth?

Populations will follow two general paths: • When faced with unlimited resources, it will grow exponentially.

• When faced with limited resources, it will grow logistically.

https://www.boundless.com/biology/population-and-community-ecology/environmental-limits-to-population-growth/exponential-growth/

CC By 3.0

• Populations grow rapidly with ample resources (biotic potential), but as resources become limited (environmental resistance), population growth rate slows and levels off.

• Carrying Capacity (K) is the maximum number of organisms that an area can support for longer lengths of time.

Logistic GrowthCan you think of some resources that could limit population growth? Characterize these resources as abiotic or biotic.

Exponential and Logistic Population Growth: J-Curves and S-Curves

• As a population levels off, it often fluctuates slightly above and below the carrying capacity.

Overpopulation Video

By the year 2020, 9 to 10 billion humans are expected to inhabit the planet. Do you think the world is overpopulated?

Check out the link below for a great video on the topic!

http://overpopulationisamyth.com/