1. MRS. PITTALUGA – 8 TH GRADE SCIENCE POPULATION ECOLOGY

2. NC ESSENTIAL STANDARD 8.L.3 – Understand how organisms interact with and respond to the biotic and abiotic components of their environment 8.L.3.1 – Explain how factors such as food, water, shelter, and space affect populations in an ecosystem I can classify examples of factors that limit a population’s growth as either density-independent or density-dependent.

3. WHAT IS A POPULATION? A group of organisms belonging to the same species that live in a particular area. Described based on size, density, or distribution.

4. POPULATION DISTRIBUTION Dispersion is the pattern of spacing among individuals within the boundaries of the population Clumped – individuals are grouped in clusters Uniform – individuals are evenly distributed Random – each individual is positioned independent of the others

5. POPULATION DENSITY Result of the processes that add individuals to a population and those that remove individuals. Immigration – individuals moving into an area Emigration – individuals moving away from an area Birth rate – number of births in a population Death rate – number of deaths in a population Determined by finding the number of individuals in a given area Pop. Density = # of individuals ÷ unit of area Affected by limiting factors

6. Births Births and immigration add individuals to a population. Immigration Deaths and emigration remove individuals from a population. Deaths Emigration

7. LIMITING FACTORS Factors that can cause a population size to decrease. Density-dependent factors – only affect a population when the density reaches a certain level Competition Predation Disease Density-independent factors – affect a population regardless of the density Natural disasters Temperature Human activities

8. SOMETHING TO THINK ABOUT Suppose your parents offer you a choice for allowance this month: You may have $5 a week OR you will get a penny on the 1 st and each day afterward, they will double the amount from the day before. Which do you choose, and why?

9. POPULATION GROWTH Exponential Growth (J-curve) Shows populations growing unrestricted and very rapidly Resources are plentiful, birth rate and immigration are high Unrealistic and unstainable Human population is currently growing at an exponential rate Logistic Growth (S-curve) Shows populations growing rapidly but then leveling off Resources are limited Carrying capacity – the maximum number of organisms that the environment can support based on available resources More realistic growth model

10. POPULATION GROWTH