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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.

What factors affect population growth? Number of births Number of deaths Emigration/Immigration

O Immigration- the movement of individuals moving into an area O Emigration-the movement of individuals moving out of an area

O A decrease in birth rates and an increase in death rates may lead to a ______ in population growth.

O A decrease in birth rates and an increase in death rates may lead to a decrease in population growth.

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

Logistic Growth O As resources become less available, growth slows down or stops O S-shaped curve

Phases of Logistic Growth O Lag phase O Exponential growth phase O Deceleration O Stable equilibrium

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

Limiting Factors O Factors that cause population growth to decrease O Includes: O Density-dependent O Density-independent

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

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

Activity O This activity will demonstrate exponential growth of a virus while demonstrating a factor that limits population growth of humans

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

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

O EfcE EfcE

Human Population Growth O The size of human population tends to increase with time. O Demography is the scientific study of human populations.

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

O What advances helped lead to the increase in human population growth? O Agricultural O Industrial O Improved Sanitation O Improved medicine and healthcare

O Demographic transition- a dramatic change in birth and death rates O Age-structure diagrams- population profile

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

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

United States Rwandan Population Percentage of Population

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

Peppered Moth O Melanistic moth became increasingly common near areas of industry O Pale or typical moth prevails in areas absent of heavy industry

Human Activities O What are some human activities that have affected the environment? O Hunting and Gathering O Agriculture O Industrialization /Urbanization

Hunting and Gathering O Early hunters and gatherers caused extinction of animals. O Examples: Woolly mammoths, giant ground sloths, saber tooth cats

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

Agriculture O Green Revolution O Specialized Crops, pesticides, irrigation O Industrialized agriculture

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