1. Question Would you rather be paid $100 a day for a month or 1 penny the first day, 2 pennies the second day, 4 pennies the next day, 8 pennies the next day…etc. for the rest of the month? EXPLAIN YOUR ANSWER

2. $100 a day equals $3,000 for the month. Starting with one penny, two pennies on the second day, 4 on the third day, 8 on the fourth day, etc. 1x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2 x2x2x2x2x2x2x2x2x2x2x2x2=

3. Population Growth I will call on a student to give me a beginning population (# between 10-1000) I will call on another random student to give me a birth rate (Crude birth rate is the number of births per year per 1000 adults) (# between 5-40) We’ll put the data into a spread sheet to see what kind of growth occurs

4. population growth.xls

5. Exponential Model of Population Growth Population increases rapidly with no limit What will a graph look like? Rare in nature. Why? “J” shaped curve Limit on the amount of resources (food / space)

6. limiting factors Populations can’t grow exponentially forever because of limiting factors. Limiting Factors can be: BIOTIC– predators, food availability, disease, competition from their own species ABIOTIC– space, water, shelter, nutrients, salinity, temperature.

7. How populations change Immigration (coming in) Emigration (going out/leaving) Growth rate = (births + immigration) – (deaths + emigration) If (births + immigration) > (deaths + emigration), population INCREASES If (births + immigration) < (deaths + emigration), population DECREASES If (births + immigration) = (deaths + emigration), population stays the same INCREASE size DECREASE size Births Deaths (mortality)

8. logistic growth AKA “S-curve” or sigmoidal More realistic model than exponential. Populations reach carrying capacity. Carrying capacity- the number of individuals the environment can support over a long time period What alters the carrying capacity of an environment?

9. Logistic Model of Population Growth Accounts for influence of limiting factors What will the graph look like? Stretched out “S” When population is small, birth rate is higher than death rate As population reaches carrying capacity, the difference between birth rate and death rate decreases When at carrying capacity, birth rate is equal to death rate

11. Wrap Up In the Oh Deer activity we learned about biotic and abiotic factors, how they are part of an ecosystem and how they influence the deer population. In a sentence or two, explain (in general terms) what a limiting factor is and its effect on a population.