Take a seat, Get out your PENCIL!

Take your HW out (finished lab)

Changes to Populations

4 factors that effect the size of a population

Increase Population– 1) Birth– 2) Immigration (entering a population)

Decrease Population– 3) Death – 4) Emigration (leaving a population)

See if you can create an equation using these 4 terms for Population Growth, Population Decrease, Population Stability

Is the population increasing or decreasing?

Populations Increase: – When Immigration + Births > Death + Emigration

Population Remains Stable:– When Immigration + Births = Death + Emigration:

Populations Decrease: – When Immigration + Births < Death + Emigration

What are Limiting Factors?

Anything that prevents the growth of a population

What would happen without limiting factors?

Carrying Capacity (k)

The maximum population a species can maintain in a certain area without damaging the ecosystem.

Population can stabilize at K

What happens when a population goes above carrying capacity?

Populations can crash if #s go above K

29 introduced in 1944

More than 6,000 by 1963

Down to 42

Seasonal Fluctuations

What will happen with World Population?

Everybody Out of Their Seats

Go to the back of the room… You are all the population of deer in PA. Lets progress through the year, and test the

effects of limiting factors on a population. Ideally we will have 5 deer at the end of the

year before breeding.

Limiting Factor #1: Space

Territorial Animals need a large amount of space.

Loss of Habitat causes the decline of many species.

Who took my towel?

Loss of Space/Habitat Example: Bluebirds

Loss of trees/wooden posts caused a huge decline

Between 1935-1985 numbers declined by 90%

Limiting Factor #2Food and Water

Leads to death via dehydration, starvation

Some animals will emigrate

Organisms that rely on one type of food are severely affected

Food and Water Example: Snowshoe Hare and Lynx

Limiting Factor #3: Climate and Weather

Temperature changes can affect plants and animals

Floods and storms can cause death & destruction of habitat

Climate Changes Example:Mosquito Populations

Mosquitoes breed in standing water

Rainfall creates puddles of standing water

Temperature Changes: Coffee Habitat

Impact of Temperature

Rise on Robusta Coffee

in Uganda.

*Developing countries,

whose economies often

rely heavily on one or two

agricultural products, are

especially vulnerable to

climate change.

*This graphic shows that

With an increase of only

2 degrees Celsius, there

would be a dramatic

decrease in the amount

of land suitable for

growing Robusta coffee

in Uganda.

Limiting Factor #4:Cover

Protection from predators

Protection from weather

Cover Example:Ruffed Grouse

Ruffed Grouse- Requires brushy forests for cover and food. Most of Pa’s forest were logged (cut down) 80 to 100 years ago. They grew into brushy forest allowing grouse populations to increase. Forests are now maturing reducing cover and food causing populations to decline. Land development has also reduced populations

Limiting Factor #5:Increase Predation

An increase in the number of predators to an area will impact prey species.

Predation Example: House Cats!

Predicted that in one year house cats kill 1 billion songbirds!

Limiting Factor #6:Disease

Spread quickly through high density populations

Can devastate populations with low genetic diversity

Disease: West Nile Virus

Mosquito born disease

5,697 crows reported dead in NYS in 1999

White Nose Syndrome

Fungus that has killed over one million bats 90-100% of some species of hibernating bats

are in danger of being killed.

Limiting Factor #7:Light

Plants that cannot tolerate too much or too little light can be affected

Light Example:Tree Growth and Shade

Aspen Pine Poplar = intolerant, will dominate young forests

Beech, Fir, Hemlock, Maple = tolerant will dominate older forests

Limiting Factor #8:Human Presence

Close proximity to humans causes some species to emigrate

Other species thrive

Reflection

Think of an example where an organism does not have enough limiting factors.

What is the organism, how does this affect the habitat around that organism?

Changes in Population

Competition

Limiting factors lead to competition among organisms for available resources

A loss in a limiting factor can contribute to a decline in populations

Increased due to exotic species

Exotic Species- Introduced species not native or endemic to the area in question.