population growth how do communities change over time?
TRANSCRIPT
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Population GrowthPopulation Growth
How do communities change over time?
How do communities change over time?
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Characteristics of PopulationsCharacteristics of Populations• Geographic distribution- describes the
area inhabited by a population• Distribution density- the number of
individuals per unit area• Growth rate- increase/decrease per unit
time• Age Structure-how many people of
different ages make up a given population
• Geographic distribution- describes the area inhabited by a population
• Distribution density- the number of individuals per unit area
• Growth rate- increase/decrease per unit time
• Age Structure-how many people of different ages make up a given population
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Population GrowthPopulation Growth• Number of births (birth rate)• Number of deaths (death rate)• Movement into a population (immigration) and
movement out of a population (emigration)Examples:
• Number of births (birth rate)• Number of deaths (death rate)• Movement into a population (immigration) and
movement out of a population (emigration)Examples:
• ↑ birth rate + ↓ death rate= ↑ pop. growth• ↑ birth rate + ↑ death rate = ↔ pop. Growth• ↑ immigration = ↑ pop. Growth• ↑ emigration = ↓ pop. Growth• Immigration = emigration = ↔ pop. growth
• ↑ birth rate + ↓ death rate= ↑ pop. growth• ↑ birth rate + ↑ death rate = ↔ pop. Growth• ↑ immigration = ↑ pop. Growth• ↑ emigration = ↓ pop. Growth• Immigration = emigration = ↔ pop. growth
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Population growthPopulation growth
• Populations will grow until they reach their biotic potential, unless they are limited by factors in the environment
• This type of growth is known as a J-curve
• Populations will grow until they reach their biotic potential, unless they are limited by factors in the environment
• This type of growth is known as a J-curve
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Exponential GrowthExponential Growth
• Occurs when the individuals in a population reproduce at a constant rate– Under ideal conditions with
unlimited resources
• Occurs when the individuals in a population reproduce at a constant rate– Under ideal conditions with
unlimited resources
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Fill It In …Fill It In …
Define “exponential growth”:Define “exponential growth”:
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Population growthPopulation growth
• Limiting factors, such as availability of food, water, and space establish a carrying capacity for populations
• This type of growth is known as a S-curve.
• Limiting factors, such as availability of food, water, and space establish a carrying capacity for populations
• This type of growth is known as a S-curve.
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Logistic GrowthLogistic Growth
• Occurs when a population’s growth slows or stops following a period of exponential growth
• Occurs when a population’s growth slows or stops following a period of exponential growth
•As resources become less available, the growth of a population slows or stops
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Fill It In …Fill It In …
List limiting factors for a population of dandelions:
List limiting factors for a population of dandelions:
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Population growthPopulation growth
• Carrying capacity is defined as the number of individuals an environment can support.
• Carrying capacity is defined as the number of individuals an environment can support.
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Population growthPopulation growth
• Limiting factors in the environment help to maintain ecosystem stability by allowing populations to fluctuate around the carrying capacity.
• This is called dynamic equilibrium.
• Limiting factors in the environment help to maintain ecosystem stability by allowing populations to fluctuate around the carrying capacity.
• This is called dynamic equilibrium.
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Population growthPopulation growth• Density dependent
factors have a greater effect on a population when there is a higher population density (the number of individuals in a given space).
• For example, competition, predation, and the spread of infectious diseases are density-dependent factors.
• Density dependent factors have a greater effect on a population when there is a higher population density (the number of individuals in a given space).
• For example, competition, predation, and the spread of infectious diseases are density-dependent factors.
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Population growthPopulation growth• Density independent
factors influence the size of a population regardless of its density.
• For example, natural disasters such as forest fires are density independent factors.
• Density independent factors influence the size of a population regardless of its density.
• For example, natural disasters such as forest fires are density independent factors.
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Age StructureAge Structure
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Check Yourself!Check Yourself!
1. What kind of curve illustrates exponential growth?
2. What determines the carrying capacity of the environment?
3. List 3 examples of limiting factors.
1. What kind of curve illustrates exponential growth?
2. What determines the carrying capacity of the environment?
3. List 3 examples of limiting factors.
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Population growthPopulation growth• Succession is the
idea that communities will replace other communities in a predictable, orderly way; this happens because every community alters the physical factors of the environment.
• Ex. As trees grow, they produce shade.
• Succession is the idea that communities will replace other communities in a predictable, orderly way; this happens because every community alters the physical factors of the environment.
• Ex. As trees grow, they produce shade.
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Check Yourself!Check Yourself!
1. What kind of curve illustrates exponential growth? J-CURVE
2. What determines the carrying capacity of the environment?
3. List 3 examples of limiting factors.
1. What kind of curve illustrates exponential growth? J-CURVE
2. What determines the carrying capacity of the environment?
3. List 3 examples of limiting factors.
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Check Yourself!Check Yourself!
1. What kind of curve illustrates exponential growth? J-CURVE
2. What determines the carrying capacity of the environment? LIMITING FACTORS
3. List 3 examples of limiting factors.
1. What kind of curve illustrates exponential growth? J-CURVE
2. What determines the carrying capacity of the environment? LIMITING FACTORS
3. List 3 examples of limiting factors.
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Check Yourself!Check Yourself!
1. What kind of curve illustrates exponential growth? J-CURVE
2. What determines the carrying capacity of the environment? LIMITING FACTORS
3. List 3 examples of limiting factors. FOOD, WATER, AND SPACE
1. What kind of curve illustrates exponential growth? J-CURVE
2. What determines the carrying capacity of the environment? LIMITING FACTORS
3. List 3 examples of limiting factors. FOOD, WATER, AND SPACE