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PowerPoint on human popula0on Read Ch. 4 in textbook See other PowerPoint for more help Read other resources & answer prac0ce ques0ons
• Popula'on: Individuals inhabi0ng the same area at the same 0me • Popula'on Dynamics: Popula0on changes due to: • Popula'on size: # of individuals • Popula'on density: popula0on size in a certain space @ a certain 0me • Age structure: Propor0on of individuals in each age group in a popula0on
• Bio'c Poten'al: Factors that allow a popula0on to increase under ideal condi0ons, poten0ally leading to exponen0al growth • Abio'c factors: light, temperature, nutrients in the environment • Bio'c factors: reproduc0ve rate, ability to migrate, defense mechanisms, ability to cope with adversity
• Popula'ons show 2 types of growth: • Exponen0al • Logis0c • Exponen'al • J-‐shaped curve • Growth is independent of popula0on density • Logis'c • S-‐shaped curve • Growth is not independent of popula0on density
• Early hunter gatherers • Nomadic • Rise of agriculture • Necessary for survival • Animals become ex0nct via preda0on & altered habitat • Humans began to cul0vate their own food
• Agriculture gives rise to ci'es • Food produced in country; consumed by city • Food wastes aren’t returned to soil • Soil become less produc0on • Waste is concentrated in the city • Popula'on control in medieval socie0es due to plagues
• Industrializa'on • Children are viewed as a source of cheap labor • Led to exponen0al growth of popula0ons • By 1900s, birth rate in the industrialized world dropped • Rise in standards of living • Safe & inexpensive birth control • Increase in cost of child rearing
10000
developed countries less developed countries
8000
6000
4000
2000
0 1750
1950
1995
2025
2100
Popula'on Projec'ons
Over 95% of this increase" will take place in “Developing" Countries”"
• Current world popula'on is
7,301,602,108
• There are just three source of change in popula0on size: • Fer'lity • Mortality • Migra'on • Immigrants vs. emigrants
• What will happen if we con0nue to grow in popula0on size? • What will happen if developing countries con0nue to grow? • What’s the solu0on?
• What are the 3 most populated countries?
CHINA, INDIA, UNITED STATES
• What type of countries are growing most rapidly?
DEVELOPING COUNT RIES • What is the current world popula0on?
7 BILLION PEOPLE
• We do not know how long we can con0nue increasing the earth’s carrying capacity for humans without seriously degrading the life-‐support system that keeps us & many other species alive
• Reasons for human popula'on increase: • Movement into new habitats & climate zones • Early & modern agriculture methods • Control of infec0ous diseases
• Popula0on growth in developing countries is increasing 9 'mes faster than developed countries • 2050 • 95% of growth in developing countries
• Thomas Malthus considered the consequences of human popula0on growth on the Earth’s resources in “An Essay on the Principle of Popula0on” (1798) • Paul Ehrlich wrote the Popula'on Bomb in 1968
• Popula0on size increases because of births & immigra'on • Popula0on size decreases because of death & emigra'on • The average # of children born to women in a popula0on (total fer'lity rate) is the KEY factor that determines popula0on size
CBR (Crude birth rate) = # of births/1000 persons CDR (Crude death rate) = # of deaths/1000 persons Growth Rate = (b + i) – (d + e)
• Net migra'on is the # of immigrants minus emigrants
• Total Fer'lity Rate (TFR)
• The avg. # of children born to a woman • Avg. in developed countries = 2 • Avg. in developing countries = 3.8
• Replacement Fer'lity Rate (RFR)
• The # of children a couple must have in order to replace themselves
• What is family planning?
• Family planning are measures enabling parents to control their # of children
• Goals of Family Planning: • • • •
Not to limit births For couples to have healthy kids For couples to be able to care for their kids For couples to have the # of kids they want
• Influen'al popula'on factors:
• Birth control/access to contracep0ves
• • • • • •
Status of women Level of poverty Availability of educa0on Restric0ons on immigra0on Benefits for lowered reproduc0on Access to affordable health care
• China’s program is the best known popula0on control program • Government perks:
Free educa0on & health care Increased personal & family incomes Increased legal marrying age for women Contracep0ves, abor0ons, & steriliza0ons free of charge • Preferen0al housing & re0rement income • • • •
• Family planning efforts began in 1970 • TFR fell from 5.7 to 1.8 • Popula'on control is extensive, intrusive, & strict
• Popula0on s0ll growing but the rate of growth has slowed • Changes in lifestyle in the US during the 20th century influenced this drop
Married women working outside home Cost of raising & educa0ng children Availability of contracep0ves/abor0ons Educa0onal & employment opportuni0es for women • Cultural norms/religious beliefs • • • •
• Empowering women to reduce births
• Women tend to have fewer & healthier children when: • They have access to educa'on & paying jobs outside of the home • Their society doesn’t suppress their rights
• People in industrialized countries enjoy fairly easy access to contracep0ves while those is less developed countries do not • In the US, teens & poor women are the LEAST likely to use contracep0ves • Severe problems are associated with teen pregnancy
• Popula'on pyramids are bar graphs that show the age & gender composi0on of a region • Horizontal axis: gender • Male: lem • Female: right
• Ver'cal axis: age
• 5-‐year or 10-‐year age groups
• The # of males & females in young, middle, & older age groups determine how fast a popula0on grows or declines
• Age structure categories:
• Prereproduc0ve ages (0-‐14) • Reproduc0ve ages (15-‐44) • Postreproduc0ve ages (45-‐up)
• Seniors are the fastest-‐growing age group
• 3 most populated countries? CHINA, INDIA, UNITED STATES • Which type of countries are growing most rapidly? DEVELOPING COUNT RIES
• What is the avg. # of children people in developed countries have? ~2
• What is TFR? Total Fertility Rate – the avg. #
of children born to a woman
• What is RFR? Replacement Fertility Rate – the # of children a couple must have to replace themselves • What 2 factors cause a popula0on to increase? BIRTHS AND IMMIGRAT ION
• What 2 factors cause a popula0on to decrease? DEATHS AND EMMIGRAT ION
• You should be able to ID the rate of popula0on growth/decrease based on chart
• What can you interpret from the histogram?
1. A group of individuals of the same species located in the same geographical area are known as a ______________ POPULAT ION
2. Several popula0ons living in the same area are known as a _COMMUNITY __________ 3. Living & nonliving factors of a community’s environment is called its ______________ ECOSYSTEM
• Life expectancy is the # of years a person is expected to live based on sta0s0cal probability • Life expectancy for a specific person is not set
• Life span describes the longest interval of 0me a certain species is es0mated to live • The maximum human life span is about 120 years
• When a popula0on experiences a growth spurt right before it runs out of resources/ space, exponen'al growth has occurred • Formula: ΔN rate of growth x # of individuals = ΔT Change in the # of Rate of growth x individuals # of individuals Change in time
ΔN rN = ΔT
rate of growth formula
• Researchers use the rule of 70 to es0mate popula0on doubling • By dividing 70 by the annual % growth rate, you get a popula0on’s approximate doubling 'me in years
• The peak # of individuals of a species supported in a sustainable manner by an CAPACITY ecosystem is called its _CARRYING __________________
• Some popula0ons grow more slowly for internal & external reasons • Internal reasons may include: hormone regula0on; maturity; body size • External reasons may include: food & habitat accessibility; predator popula0on
• Dense popula0ons increase pressure on resources like food & water • Density-‐dependent factors are related to the extra pressure on food & water due to so many individuals living in one area • Compe00on • Preda0on • Disease • Density-‐independent factors such as drought, early frost, fires, hurricanes, etc.
1. Which term is used to describe the longest 0me interval a certain species is es0mated to live? A. Mortality B. Nutri0on C. Decades D. Life span E. Fer0lity
2. When popula0ons experience an unrestricted overshoot before limited resources, space, or disease cause a dieback, it is known as... A. Logarithmic growth B. a p curve C. Exponen0al growth D. Proven reserves E. Bio0c exponen0al
3. The rule of 70 is used to es0mate A. entrepreneurial species B. popula0on doubling C. density-‐dependent species D. infant development E. poten0al of a new Starbucks in a neighborhood
4. The # of years of individual is sta0s0cally likely to live is called his or her A. species dura0on B. natality C. life expectancy D. mortality E. gene0c drim
5. Human popula0on control A. has never worked B. has reaped substan0al benefits in China C. is impossible in developed na0ons D. is not needed E. is not possible with today’s technology
• Carrying Capacity refers to the # of organisms that can be supported ina given area sustainably • Popula0on size cannot be sustained above carrying capacity, eventually it will crash • In equa0ons, carrying capacity is represented by the lerer K
• A popula0on’s bio'c poten'al is the maximum rate at which a popula0on can grow • Occurs when resources are unlimited • If unchecked, will result in a J-‐curve
• Malthus – 19th century England • Concerned about the overpopula0on of the young; inability of resources to keep up with popula0on; irresponsibility of lower classes • Charles Darwin – On the Origin of Species (1859) • Incorporated some of Malthus’ ideas • Limited resources results in compe''on • Organisms that survive pass on gene adapta0ons to their offspring
• Organisms have adapted either to: • Maximize growth rates in environments that lack limits • Maintain popula'on size @ close to carrying capacity in stable environments
• Species that have high reproduc0ve rates are known as r-‐strategists • Species that reproduce later in life & with fewer offspring are called K-‐strategists
• r-‐strategists • • • • • • •
Mature rapidly Short lived Tend to be prey Low parental care Tend to be small creatures Type III survivorship curve Examples? Insects, algae, bacteria, rodents & annual plants
• K-‐strategists • • • • • • • • •
Mature slowly Long lived Tend to be both predator & prey Have few offspring High parental care Popula0on size stabilizes near K Tend to be larger creatures Type I or II survivorship curve Examples? Humans, elephants, cac0, & sharks
• Survivorship curves show age distribu0on characteris0cs of species, reproduc0ve strategies, & life history • Type I: late loss • Type II: constant loss • Type III: Early loss
Popula0on change = (crude birthrate + immigra0on) – (crude death rate + emigra0on) Crude birth rate =
RULES T O DO WELL WITHOUT A CALCULAT OR: • Use scienti*ic notation whenever #s are large or small 650,000 = 6.5 x 105 0.000543 = 5.43 x 10-‐4
RULES T O DO WELL WITHOUT A CALCULAT OR: • When adding or subtracting #s with exponents, the exponents of each # must be the same before you can do the operation
Example: (1.9 x 10-3) - (1.5 x 10-4 ) (19 x 10-4 ) - (1.5 x 10-4 ) = 17.5 x 10-4
RULES T O DO WELL WITHOUT A CALCULAT OR: • When multiplying #s with base 10 exponents, multiple the 1st factors, & then add the exponents
Example: (3.1 x 105) (4.5 x 105) = 13.95 x 1010 or 1.4 x 1011
RULES T O DO WELL WITHOUT A CALCULAT OR: • When dividing #s with base 10 exponents, multiple the 1st factors, & then subtract the exponents
Example: 9 x 10 5 = 3 x 10 2 3 x 10 3
RULES T O DO WELL WITHOUT A CALCULAT OR: • Show ALL of your work & steps of calculations, even if they are too simple • Show ALL of your UNITS
• Species that have high reproduc0ve rates are known as _r__-‐strategists • Species that reproduce later in life & with fewer offspring are called _K __-‐strategists • Type III (early loss) survivorship curve represents a _r__ -‐ strategist • A species that has few offspring & high parental care are _K __-‐strategists
1. Humans 2. Sharks 3. Rodents 4. Plants
____ K
K ____ ____ r ____ r
5. Elephants ____ K 6. Insects
____ r
• Many different factors affect human population: • Historical population rates • Population distribution • Fertility rates • Growth rates • Doubling times • Demographic transition
• The rapid growth of the world’s human population over the past 100 years has been due primarily to a decrease in deaths • In 1900, the overall death rate in the US was 1.7% • In 2000, the overall death rate had dropped to 0.9%
• Increased food production & more efIicient distribution • Improvements in medical & public health technology • Improvements in sanitation/personal hygiene • Safer water supplies
• The human population has had 3 surges of growth: • Occurred when tools & *ire began to be used • Occurred during the agricultural revolution • Occurred during the industrial revolution
• ___________________-‐level fertility (RLF) is Replacement the level of fertility @ which a couple has only enough children to replace themselves • About 2 children per couple
Total fertility rate is the avg. # of • _______ children that each woman will have during her lifetime • Highest in Niger @ 7.68
• Niger = 7.68 • India = 2.65 • Israel = 2.72 • Mexico = 2.31 • USA = 2.06
1. Calculate the percentage growth rate for a country with a population of 6 million: in a year in which it had 100,000 births, 70,000 deaths, 30,000 immigrants, and 50,000 emigrants 1st step: find crude birth rate (b+i)/6mil & convert to % 2nd step: find crude death rate (d+e)/6mil & convert to % 3rd step: birth rate – death rate = growth rate
2. One thousand two hundred & seventy deer are living on an island that is eight hundred and thirty square kilometers in size. What is the population density of the deer per square kilometer? 1st step: population/area
3. A city with 53,340 people has 876 births. What is the birth rate (as a %/1000) 1st step: births/population & turn into percentage 2nd step: turn percentage into # out of 1,000
4. A village of 23,473 people has 2,342 births & 473 deaths. What is the growth rate for this village? 1st step: births - deaths 2nd step: # / population 3rd step: turn into %