Bell Work 2/8/18 Get all 8 handouts (Population Ecology) from the front table and paste them into the appropriate page on your notebook (105-112) If you did not finish your exam yesterday or did not start it due to being absent/late, come talk to me. If you are finished with your exam, please start the activity on pages 105-106 of your notebook “How do populations grow?”—includes three questions. Bring it to me when you are finished so I can grade it!

How do populations grow? Assume that a pair of rabbits produces 6 offspring and that half the offspring are male and half are female. Assume that no offspring die. If each pair of rabbits breeds only once, how many offspring would be produced each year for 5 years? Make a graph! Plot time on the x-axis and population on the y-axis.

How do populations grow? Describe the shape of your graph. Use your graph to predict the population of rabbits in 10 years and in 20 years. How can you explain that the Earth is not covered by rabbits? When you are finished answering the questions, bring it to me so I can check you off—you will be graded!

1000 900 800 NUMBER OF RABBITS 700 600 500 400 300 200 100 1 2 3 4 5 6 7 8 9 10 TIME (YEARS)

Populations

Objectives I can identify trends in population growth. I can describe the factors that affect population. I can identify density-dependent limiting factors.

Vocabulary Population density Immigration Emigration Exponential growth Logistic growth Carrying capacity Limiting factors Density-dependent limiting factors Predator-prey relationships Demography

What are the three characteristics of a population? Geographic distribution Density Growth rate Population density is the number of individuals per unit area.

What are three factors that influence population size? Number of births Number of deaths Movement Immigration is movement of an individual into an area Emigration is movement of an individual out of an area

What happens under ideal conditions? Exponential growth occurs when the individuals in a population reproduce at a constant rate. Is this a reasonable assumption for most populations?

Why does population growth slow or stop? Resources become less available Logistic growth occurs when a population’s growth slows or stops following a period of exponential growth.

When does the population slow or stop? Carrying capacity is the point where a population will cease to increase in growth due to environmental factors.

Critical Thinking Questions What factors might cause the carrying capacity of a population to change? What is the difference between logistic growth and exponential growth? What factors can change a population’s size? When you are finished answering the questions, bring it to me so I can check you off—you will be graded!

What decreases the rate of population growth? Competition Predation Parasitism and disease Drought and other climate extremes Human disturbances Limiting factors are factors that cause population growth rates to decrease.

Are any of those factors dependent on the size of the population? Competition Predation Parasitism and disease Density-dependent limiting factor (DDLF) is a limiting factor that depends on population size.

Competition as a DDLF All organisms in any ecosystem have some effect on every other organism in that ecosystem. Any resource in an ecosystem exists in a limited supply. When these two conditions appear together, competition takes place.

Competition as a DDLF Competition can occur in two ways Two members of different species Two members of the same species

Predation as a DDLF Predator-Prey relationships regulate population by predation.

Parasitism and Disease as DDLF Parasites and disease are similar to predators—they kill off segments of a population Ex. Cordyceps on grasshopper

Isle Royale Case Study https://prezi.com/xbvw9arjntee/case-study-the-wolves-of-isle-royale/

Critical Thinking Questions Give an example of a density-dependent limiting factor that has affected a human population. Describe how this factor changed the human population. If an entire lynx population disappears, what is likely to happen to the hare population on which it preys? How can a limited resource affect the size of a population? Give an example. When you are finished answering the questions, bring it to me so I can check you off—you will be graded!

How do these patterns look for humans? What was the catalyst for the sharp increase in human population? The Industrial Revolution (ca. 1750-1850)

What three factors predict/affect the growth rates in human populations? Birth rates Death rates Age structure of a population Some countries have high growth rates, while some countries have low growth rates. The scientific study of human populations is demography.

Critical Thinking Questions Why might a contagious virus that causes a fatal disease be considered a density-dependent limiting factor? How is the carrying capacity of a city’s roads similar to the carrying capacity of an ecosystem? What will happen to a population of predators if there is a sudden increase in food for the prey? Explain. How is the relationship between parasites and their hosts similar to a predator-prey relationship? If the water level of a river drops, how might that affect a fish population living in that river? When you are finished answering the questions, bring it to me so I can check you off—you will be graded!