5.1 and 5.3-Populations. Essential Question: What factors can be used to describe populations in an ecosystem?

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Erica Wade
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1 Warm up: Kahoot

2 5.1 and 5.3-Populations Essential Question: What factors can be used to describe populations in an ecosystem?

3 Describing Populations Researchers study populations : geographic range density and distribution growth rate age structure Markerboards: What would happen to the population s density if the population size stayed the same while its geographic range decreased? Which of the four characteristics above most directly determines if a population increases or decreases in size over time?

4 Density and Distribution Population density refers to the number of individuals per unit area Distribution refers to how individuals are spaced out Random Uniform Clumped

5 Growth Rate and Age Structure Growth rate-determines whether the size of the population increases, decreases or stays the same Age Structure-how many males/females of each age there are

Population Growth The factors that affect population size are: birthrate deathrate immigration: when individuals move into a new area emigration: when individuals leave an area Using

6 Population Growth The factors that affect population size are: birthrate deathrate immigration: when individuals move into a new area emigration: when individuals leave an area Using marker boards: Increase death rate Increase immigration Decrease emigration Decrease birth rate Which factors add individuals to a population? Which factors remove individuals from a population?

7 More Marker Boards! If the birth rate > death rate, what can be determined about the overall population size? Marker Boards: The population grows when the birthrate is > than the death rate, or if immigration is > than emigration = The population stays the same if birthrate is to death rate, or if immigration is = to emigration

8 Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially Population Time

9 Discussion Invasive species often experience exponential growth when introduced into a new environment. Why do you think that is? (Think about what sort of things limit growth that invasive species aren t experiencing) 1. Write 2. Share with group 3. Discuss as class

10 Logistic Growth Exponential growth does not last forever. Logistic growth occurs when a population's growth slows then stops, following a period of exponential growth. Eventually reaches its carrying capacity or maximum number of individuals that an environment can support

11 Marker boards! When a population has reached its carrying capacity: birth rate = death rate immigration = emigration Growth = 0

12 Discussion Why, in natural settings, doesn t exponential growth continue indefinitely for any species?

13 Human Population Growth The human population has increased over time, but the rate of the increase has changed For most of human existence, the rate of growth was slow due to lack of food, predators and disease Advances in civilization led to lower death rates and higher birth rates thus increasing the population

14 On paper: Read The Predictions of Malthus at the bottom of page 142 What limiting factors, according to Malthus, affect the human population? How are these similar/different to limiting factors affecting other populations? Explain how the size of the global human population can increase while the rate of growth decreases.

while other countries have low growth rates Demographic

15 Age Structures Birth rates, death rates and the age structure of a population help predict why some countries have high growth rates while other countries have low growth rates Demographic transition-change from high birthrates and death rates to low birthrates and death rates

16 How to read age structure diagrams

17 Marker Boards! 1. Which country will have the highest growth rate? 2. Which country will have a negative growth rate?

18 Closure: Populations kahoot

19 Why are invasive species so bad for ecosystems? Give some examples. What methods of control are in place already? What more can we as humans do?

Chapter 8. Population Ecology. Chapter Overview Questions. Ø What are the major characteristics of populations?

Chapter 8. Population Ecology. Chapter Overview Questions. Ø What are the major characteristics of populations? Chapter 8 Population Ecology Chapter Overview Questions Ø What are the major characteristics of populations? Ø How do populations respond to changes in environmental conditions? Ø How do species differ