populations. populations: groups of individuals that belong to the same species and live in the same...
TRANSCRIPT
![Page 1: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/1.jpg)
Populations
![Page 2: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/2.jpg)
Populations
• Populations: groups of individuals that belong to the same species and live in the same area
![Page 3: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/3.jpg)
Characteristics Of A Population
• There are three important characteristics of a population: 1. Geographic Distribution, 2. Density, and 3. Growth- Geographic distribution, or range, is the area in which a population lives- Population density is the number of individuals per unit area. An example is the number of people per square kilometer.- Growth rate is how quickly a population increases or decreases in size.
![Page 4: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/4.jpg)
Geographic Distribution Of Termites
![Page 5: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/5.jpg)
Population Density
![Page 6: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/6.jpg)
Population Density
• Dispersal patterns– Random– Clumped– Uniform
Random
Clumped
Uniform
![Page 7: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/7.jpg)
Patterns
• Reproductive pattern = life-history pattern– Two main types of patterns:
• Rapid life-history patterns• Slow life-history patterns
![Page 8: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/8.jpg)
Patterns
• Rapid life-history patterns– Changing or
unpredictable environment
– Small species– Mature rapidly– Reproduce early– Short life span
![Page 9: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/9.jpg)
Patterns
• Slow life-history pattern– Large species– Stable environments– Reproduce slowly– Matures slowly– Long life span– Stay at or near carrying
capacity
![Page 10: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/10.jpg)
Factors That Affect Population Size
• Three factors can affect population size: 1. the # of births, 2. the # of deaths, and 3. the # of individuals that enter and leave the population.
• Populations increase through births and immigration. Populations get smaller through deaths and emigration.– Immigration is the movement of individuals into an
area.– Emigration is the movement of individuals out of an
area
![Page 11: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/11.jpg)
How Populations Grow• Exponential growth occurs when members of a
population reproduce at a constant rate. (This growth pattern is shown by a J-shaped curve.)– As the population grows, the number of reproducing
members keeps rising. Thus the population grows faster and faster.
– Under ideal conditions with unlimited resources, a population will grow exponentially.
– In nature, exponential growth does not go on for long. • Resources are used up in time. • This causes population growth to slow or stop. • Predators and disease also slow exponential
growth.
![Page 12: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/12.jpg)
Exponential Growth Graph
![Page 13: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/13.jpg)
How Populations Grow• As resources become less available, the growth of a
population slows or stops. This is called logistic growth. (Logistic growth is shown by an S-shaped curve.)– Logistic growth occurs when a population's growth
slows or stops following a period of exponential growth. Example, if food resources start to run out or space becomes limited, a population that was growing exponentially may start to exhibit logistic growth.
– The population size when growth stops is called carrying capacity.
![Page 14: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/14.jpg)
Carrying capacity is the number of individuals of a specific species that a given environment can support.
![Page 15: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/15.jpg)
Limits To Growth
• A limiting factor is anything that slows population growth. There are two kinds of limiting factors.– Density-dependent limiting factors – Density-independent limiting factors
![Page 16: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/16.jpg)
Limiting Factors
• Density-dependent limiting factors rely on population size. They include competition, predation, parasitism, and disease.– Competition occurs when organisms are using the
same ecological resources at the same time.– Predation occurs when one organism captures and
feeds on another organism. The organism that gets eaten is the prey. The organism that eats the prey is the predator.
• Predator-prey relationships can affect the size of both the predator population and the prey population.
![Page 17: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/17.jpg)
Limiting Factors
– Parasitism is a symbiotic relationship in which one organism benefits at the expense of another species
– Disease is an abnormal condition affecting the body of an organism.
• Diseases can come from bacteria, viruses, and genetics– Examples: cancer, heart disease, AIDS
![Page 18: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/18.jpg)
Limits To Growth• Limiting factors continued
– Density-independent limiting factors do not rely on population size.
• They include natural disasters and human activities such as damming rivers.
• When such factors occur, many species show a rapid drop in population size.
![Page 19: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/19.jpg)
Human Population
![Page 20: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/20.jpg)
Human Population Growth
• The size of the human population tends to increase with time.• For most of human existence, the population grew slowly.• About 500 years ago the population began growing faster.
– Agriculture and later industry made food more available.– Improved sanitation and medicine reduced death rates.– However, birthrates stayed high in most places. This led
to exponential growth. Today, the human population continues to grow exponentially.
![Page 21: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/21.jpg)
Agriculturebegins
Plowingand irrigation
Bubonicplague
IndustrialRevolutionbegins
Human Population Growth
![Page 22: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/22.jpg)
Human Population Growth
![Page 23: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/23.jpg)
Human Population Explosions
The Population Explosion– Around 1650, improvements in hygiene, diet, and
economic conditions further accelerated population growth.
– After World War II, the human population grew at the fastest rate in history, largely because of better sanitation and medical care in poorer countries.
![Page 24: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/24.jpg)
Human Population Growth Due To Medicine Practices And Sanitation
![Page 25: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/25.jpg)
Advances in Human Technology = Growth
![Page 26: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/26.jpg)
Human Population Growth Vs Species Extinction
![Page 27: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/27.jpg)
Study Of Population Growth
• Demography is the scientific study of human populations.
• Demographers try to predict how human populations will change over time.
• 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.
![Page 28: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/28.jpg)
Study Of Human Population Growth
• Over the past century, population growth in the U.S., Japan, and much of Europe slowed greatly.
• Demographers call this shift a demographic transition.– The transition began as death rates fell, causing a
brief rise in population growth. Then birthrates fell, slowing population growth.
– Most people live in countries that still have high population growth.
![Page 29: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/29.jpg)
Human Population Growth
![Page 30: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/30.jpg)
Human Population Growth
![Page 31: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/31.jpg)
![Page 32: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/32.jpg)
Study Of Human Population Growth
• Demographers use age-structure diagrams to help predict population growth. An age-structure diagram is a bar graph.
• An age-structure diagram shows how many people of each gender are in each age group in the population.
• To predict how the world population will change, demographers need to think about the age structure of each country as well as the number of people with fatal diseases, including AIDS.
![Page 33: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/33.jpg)
U.S. Population Rwandan PopulationMales MalesFemales Females
Age Distribution
![Page 34: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/34.jpg)
![Page 35: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/35.jpg)
![Page 36: Populations. Populations: groups of individuals that belong to the same species and live in the same area](https://reader035.vdocuments.net/reader035/viewer/2022062423/56649d755503460f94a55c3b/html5/thumbnails/36.jpg)
YouMe