#26 Population dynamics

Warm-up: Trophic Level Autotroph or heterotroph Producer, primary consumer, secondary consumer, tertiary consumer Human Snake Giraffe Deer Algae Owl

No population can grow forever No population can grow forever. Every population has a limit to its growth based off the number of available resources. *A limiting factor prevents the continuing growth of a population within an ecosystem. There are several things that can limit a population, we will learn the terminology in the following slides

*Population limiting factors Population growth rate is how fast a given population grows Factors that influence this are: Natality ( _________ rate) Mortality ( _________ rate) Emigration (the number of individuals moving _____________ a population) Immigration (the number of individuals moving ____________ a population) birth death away from to

*Population Characteristics Population Density: The number of organisms per unit area Spatial Distribution: Dispersion: The pattern of spacing a population has within an area 3 main types of dispersion Clumped Uniform Random The primary cause of dispersion is resource availability

*Population Limiting Factors Density-independent factors Factors that limit population size, regardless of population density. These are usually abiotic factors They include natural phenomena, such as weather events Drought, flooding, extreme heat or cold, tornadoes, hurricanes, fires, etc.

*Population Limiting Factors Density-dependent factors Any factor in the environment that depends on the number of members in a population per unit area Usually biotic factors These include Predation Disease Parasites Competition

Clarifying classification shows organisms that share a common ancestor. These organisms are closely related shows similarities between evolved organisms

The world population continues to grow due to the average life expectancy increasing from 68 year old in 1950 to 80 years old in 2012. In addition to people living longer, people are continuing to reproduce and have offspring.

What is density? How would you calculate the population density of… Total Area: Washington D.C. 68.34 Population: Washington D.C. 646,449 Which states do you predict will have the 20 largest densities?

Population Density assignment questions

Label all the states Create a legend and color the top 20 states with the highest population density one color Color the 20 lowest density states another color and add to your legend Which states surprised you about their population density? Why? The square mileage listed accounts for land and water miles, do you think any of the rankings would change if you just calculated land mass only? If so which states? If you say no explain why If you had to calculate the population density of the entire United States, where do you think it will fall in your rankings from largest to smallest? Around what number? (This is a prediction) Do you think it will be larger or smaller then the pop Density of NC? Explain why? Find the 2012 population of USA (use BYOT) and the total square miles and find the pop density How correct were your #6 and #7? Explain mistakes you made and why those new numbers you found are logical? This week’s theme of reading across the board is “Main Idea,” why do you think it’s important to understand population density? What does it tell us about people, location, and resources?

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What population do you think this is?

Understanding Exponentials Put your pens down for a minute & think about this: An employer offers you two equal jobs for one hour each day for fourteen days. The first pays $10 an hour. The second pays only 1 cent a day, but the rate doubles each day. Which job will you accept? 15

Understanding Exponentials Population Ecology: Population Growth Rate Understanding Exponentials Now, how much would your employer owe you if you stayed at this job for another 2 weeks? Job 2 lags for a long time before exponential growth kicks in! What would happen if this type of growth took place within a population?

Creative Writing Each group will work together to develop the beginning of a story. Introduce your characters, setting, problem (limiting factor), and size of population in that characters community Pass your story to the next group 2. Each group will read the introduction of the their new story, and: Explain how the characters are being affected by the problem introduced in Part 1 (what fears/concerns does this organism have for his/herself and his population 3. Each group will read their new story, and write its ending: Explain what happened to the character and his/her population as a result of the problem; will they be doing anything to re-build their population? Explain the impact this problem had on the overall population size?

The most straightforward chain of argument goes… As the # of organisms increase Resources Become more limited Competition Among Individuals for Resources increases Competition has Effects on Birth and Death Rates SO… Does this “regulate” or just limit population size?