Populations This trio of sea otters is part of the population that lives near Monterey, California. Sea otters often rest by wrapping themselves in kelp.

Populations This trio of sea otters is part of the population that lives near Monterey, California. Sea otters often rest by wrapping themselves in kelp to keep from drifting away.

5-1: How Populations Grow
K-selected population r-selected population Time Time K= _______________ Characteristic K-selected r-selected . Lifespan ………………____…………….. ______ Mortality rate……….. ____…………….. _____ Offspring/episode…... ____……………... _____ Sexual Maturity…….. ____……………... _____ Offspring size………. _____……………. _____ Parental Care……….________ …………. _____ Population Population Carrying capacity long short low high few many late early large small extensive none

5-1: How Populations Grow
When the population increases rapidly due to a lack of environmental resistance. (B) Exponential Growth- ____________________________________________ _______________________ Carrying Capacity- _____________________________________________ ____________ Environmental Resistance- _______________________________________ ___________________________________________ The population density that can be supported by the environment. When the population encounters resistance to exponential growth due to environmental factors. E) Fluctuations- The number of organisms tends to rise above and below the carrying capacity. D) Carrying Capacity- The environment cannot support more organisms. If the population size is above the carrying capacity, organisms die. A) Beginning Growth- The population increases, the few starting members have offspring, and the population grows B) Rapid Growth- There are many organisms, each reproducing, resulting in a fast increase in the number of individuals. Growth is exponential. C) Leveling Off- As the population grows, it becomes more difficult for each organism to meets its needs. Growth slows. The graph resembles the letter ‘S’. The population suffers from environmental resistance.

5-2: Limits to Growth Limits to Population Growth:
-_________________________________________________________ There are two types of factors that keep populations in check. ____________________________________ Q: What would cause a population to decrease in numbers if the population was crowded (dense)? A) Density-Dependent Factors (______________): 1) __________ 2) _________ 3) _________ 4) ____________________ A limiting factor is a factor that causes population growth to decrease. It is based upon how dense the population is. dense population Competition Predation Parasitism Disease (can spread easy)

5-2: Limits to Growth Q: How would you explain a decrease in population when individuals are spread out (not dense)? B) Density-Independent Factors: -______________________________________ 1) _______________________________ 2) ______________ 3) _________________________ This affects populations, regardless of size. Natural disasters/Catastrophic events Human activities Seasonal cycles/Physical factors How would you classify war?

5-2: Limits to Growth How are the increases and decreases in the moose population related to the changes in the wolf population? Density Dependent or Density Independent

5-3: Human Population Growth
-Natural populations grow and decline until a balance is reached between biotic potential and environmental resistance. Humans defeat environmental resistance with intelligence and technology. Will we reach a natural limit??

Reasons for population growth: The population boom is NOT due to increased birth rate. The world birth rate is actually declining. - Medicinal advances Childhood survival (vaccines for diseases) Fatal epidemics minimized (Bubonic plague) Increased number of women reaching reproductive age (15-44). Demographics: -Birthrates, death rates, and the age structure of a population help predict why some countries have high growth rates while other countries grow more slowly. - Demographers can predict future growth using models called age-structure diagrams, or population profiles, which graph the numbers of people in different age groups in the population.

The figure below shows typical age-structure diagrams for countries that have different rates of growth Countries that have high rates of growth usually have more young people than older people. In contrast, countries that have slow growth or no growth usually have an even distribution of ages in the population.

Fertility Rates: -Demographers calculate the total fertility rate as ___________________ ________________________________________ the average number of children a woman gives birth to in her lifetime.

Current U.S. fertility rate is at a replacement level, which is 2.1 If the U.S. is at a replacement level, why does the U.S. population continue to rise? Immigration Reproductive years This pyramid reflects data from 1999

Current fertility rate in Rwanda is 4.1, which is much higher than the replacement level. From this profile, can you tell how many people live in this country? No Reproductive years This pyramid reflects data from 1999

The factors most clearly related to a decline in birth rates are increasing education and economic independence for women. -____________________________________________________________ ________________________________________ Educated women find that they do not need to bear as many children to ensure that some will survive. They may also learn family planning techniques. Women are able to contribute to their family’s increasing prosperity while spending less energy bearing and caring for children. -____________________________________________________________ _____________________________________________________________________________________ All of these reasons contribute to lower birth rates in both developed and developing countries. As countries modernize, parents are more likely to work away from home. If parents must pay for child care, children may become a financial burden rather than an asset.

How would you describe the dynamics of a country that has this as a classroom?

How would you describe the dynamics of a country that has this for agriculture?

Examples: Mexico U.S.A Japan

Mexico -1995 Total Population: 92,880,353 Fertility Rate: 2.6
Reproductive Ages Compare yourself to that of the population pyramid above. In 1995, you were in the 0-4 age bracket, but in the neighboring U.S. Imagine living in Mexico at this time and the people you would be around.

Reproductive Ages

Total Population (est.):
118,689,157 Mexico Fertility Rate: 2.2 Reproductive Ages

135,172,155 Mexico Fertility Rate: 2.0 Reproductive Ages Notice what will happen to the male-to-female ratio when the fertility rate reaches 2.0.

United States -1995 Total Population: 266,557,091 Fertility Rate: 2.1
Reproductive Ages In 1995, you belonged to the bottom bar in the population pyramid above. As the 5-year intervals progress follow the light blue bar as we approach the year Notice the changes that occur to the graph as well.

Reproductive Ages

325,539,790 United States Fertility Rate: 2.1 Reproductive Ages

Japan -1995 Total Population: 125,341,354 Fertility Rate: 1.2
Reproductive Ages Compare yourself to that of the population pyramid above. In 1995, you were in the 0-4 age bracket, but in the U.S. Imagine living in Japan at this time and the people you would be around.

Reproductive Ages

124,719,937 Japan Fertility Rate: 1.3 Reproductive Ages

Examples: Mexico U.S.A Japan

Populations This trio of sea otters is part of the population that lives near Monterey, California. Sea otters often rest by wrapping themselves in kelp.

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Populations This trio of sea otters is part of the population that lives near Monterey, California. Sea otters often rest by wrapping themselves in kelp.

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Presentation on theme: "Populations This trio of sea otters is part of the population that lives near Monterey, California. Sea otters often rest by wrapping themselves in kelp."— Presentation transcript:

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