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Published byKory Holt Modified over 9 years ago
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http://www.youtube.co m/watch?v=6WS7naoE H5o
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Characteristics of Populations O Geographic distribution- the area inhabited by a population O Population density- the number of individuals per unit area O Ex: 73 persons per square mile in the U.S.
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What factors affect population growth? Number of births Number of deaths Emigration/Immigration
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O Immigration- the movement of individuals moving into an area O Emigration-the movement of individuals moving out of an area
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O A decrease in birth rates and an increase in death rates may lead to a ______ in population growth.
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O A decrease in birth rates and an increase in death rates may lead to a decrease in population growth.
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Exponential Growth O Occurs when the individuals in a population reproduce at a constant rate. O Ideal Conditions with unlimited resources O Produces a J-Shaped Curve
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Logistic Growth O As resources become less available, growth slows down or stops O S-shaped curve
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Phases of Logistic Growth O Lag phase O Exponential growth phase O Deceleration O Stable equilibrium
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Carrying Capacity O The maximum number of individuals of a given species that the environment can support O The closer a population is to carrying capacity: the more likely resources become scarce birth-rate expected to decline death-rate expected to increase
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Limiting Factors O Factors that cause population growth to decrease O Includes: O Density-dependent O Density-independent
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Density-dependent factors O Become limiting only when the population density reaches a certain level O The percentage of the population affected increases as density of population increases O Examples: O Predation, Competition, Parasites, Disease
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Density-independent factors O Affect all populations in similar ways, regardless of population size O Intensity of effect does not increase with increased population density O Examples: O Droughts, freezes, hurricanes, floods, forest fires
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Activity O This activity will demonstrate exponential growth of a virus while demonstrating a factor that limits population growth of humans
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Instructions O Each person will get a cup with a liquid O 1 st Round O Find a partner and mix the contents of your cup with partner. Make sure the contents are mixed thoroughly O Evenly distribute the contents to cups of both partners
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O 2 nd Round O Find a new partner O Repeat Steps from 1 st Round O 3 rd Round O Find a new partner (different from 1 st and 2 nd rounds) O Repeat Steps from 1 st Round O 4 th Round O Find new partner O Repeat Steps from 1 st Round
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O http://www.youtube.com/watch?v=VcSX4yt EfcE http://www.youtube.com/watch?v=VcSX4yt EfcE
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Human Population Growth O The size of human population tends to increase with time. O Demography is the scientific study of human populations.
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O Human population growth started out very slowly O What were some limiting factors that kept the human population low? O Food scarcity O Diseases
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O What advances helped lead to the increase in human population growth? O Agricultural O Industrial O Improved Sanitation O Improved medicine and healthcare
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O Demographic transition- a dramatic change in birth and death rates O Age-structure diagrams- population profile
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Demographic Transition O More-developed countries doubled population between 1850 and 1950 O Caused by decline in death rate O This was followed by decline in birthrate O Only modest growth between 1950 and 1975 O Stable Growth
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Demographic Transition O Yearly growth of less-developed countries peaked between 1960 and 1965 at 2.5 % O Since then, death rate and birthrate have fallen O Collective birthrate now 1.5% O But many LDCs have not participated in this decline
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United States Rwandan Population Percentage of Population
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More-developed vs. Less Developed Countries O More-developed countries O North America, Europe, Japan, Australia O Low growth O Higher standard of living O Less-developed countries O Some countries in Latin America, Africa, and Asia O Population growth is expanding rapidly O Many in poverty
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Peppered Moth O Melanistic moth became increasingly common near areas of industry O Pale or typical moth prevails in areas absent of heavy industry
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Human Activities O What are some human activities that have affected the environment? O Hunting and Gathering O Agriculture O Industrialization /Urbanization
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Hunting and Gathering O Early hunters and gatherers caused extinction of animals. O Examples: Woolly mammoths, giant ground sloths, saber tooth cats
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Hunting and Gathering O Early human populations in the Mediterranean region ate large quantities of tortoises and shellfish O Depleted these sources O Were then forced to eat hares, partridges, and other small mammals and birds
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Agriculture O Green Revolution O Specialized Crops, pesticides, irrigation O Industrialized agriculture
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Agriculture O Clearing of large portions of land O Increased erosion O Runoff O Loss of biodiversity O Pest Resistance O Soil and water pollution
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