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

Limiting Factor #1: Space/Loss of Habitat 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 numbers declined by 90%

Limiting Factor #2 Food 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 % 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

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. OTHER NAMES: non-native & invasive