How Many People Can Live on Planet Earth?

7 Billion Videos7 Billion Agree or DisagreeIntro to Populations - NotesPopulationshttps://www.youtube.com/watch?v=4B2xOvKFFz4

https://www.youtube.com/watch?v=VcSX4ytEfcEhttp://www.youtube.com/watch?v=sc4HxPxNrZ0Population: all the members of a species living in the same place at the same time. Understanding Populations3 words to describe a population:Size (7 billion people on the planet)Density (people per square mile)Dispersion (distribution or arrangement of its individuals within a given amount of space)EvenClumpedRandom

DensityDispersion

How Does a Population Grow?Growth rate: change in the size of a population over a given period of time.

Positive (+): birth rate > death rateZero (0): birth rate = death rateNegative (-) = birth rate < death rate

Change in population sizeBirthsDeaths=-How Fast Can a Population Grow?Reproductive potential: the maximum number of offspring that a given organism can produce.

Examples:It would take elephants 750 years to produce 19 million descendentsIt would take bacteria a few days to produce 19 million descendents.

What is another organism with a low reproductive rate?How Fast Can a Population Grow?High reproductive potential when individualsProduce more offspring at a timeReproduce more oftenReproduce early in life

Examples:Insects can reproduce when they are a few hours or days oldHumans reproduce after a number of yearsHow Fast Can a Population Grow?Exponential Growth: when populations grow faster and fasterOccurs when a population has:Plenty of food and spaceNo competition or predators

What Limits Population Growth?Carrying Capacity: the largest population that an environment can support in any given time

What Limits Population Growth?Limiting resources: a natural resource that is consumed at the same rate at which the ecosystem produces the resource

Example:Limiting FactorsFoodWater Sunlight (producers)SpaceDiseaseCompetitionPredationTwo Types of Population RegulationDensity DependentDensity IndependentSame species close togetherDisease spreads from one to the nextDeath occurs quicklyPortion of a population dies regardless of population densityExample: Natural disasters (hurricane)If humans have no natural predators, how is our population controlled? Human Carrying Capacity?Current human population: approx 7.12 billion peopleRanges estimated from 4-16 billion people Hard to estimate how many people this world can holdTechnological innovationsMedical breakthroughshttp://www.census.gov/popclock/

What caused this rapid growth?What sparked our growth?Industrial Revolution (~1750)Modern medicine (20th century)Death rates DROPPED due to better careAgricultural AdvancesTransportation AdvancesHuman Population GrowthPopulation (in billions)123456789Year180419271960197419871999201220272046Years elapsed between milestones-- 12333141312131619Source: U.S. Census Bureau- World POPclock ProjectionWhat takes us out?Pair and Share (2 min):Humans are at the top of any food web resulting in no natural predators to keep our populations in checkWhat are the limiting factors of the human population?How are we different than other species in regards to population control? Whats our limiting factor?Disease: Bubonic Plague, AIDS, Flu, MalariaAccess to foodAccess to clean waterCompetition (a.k.a. War)

EventCasualtiesAmerican War Deaths, all-time600,000India Famine (1769-70)3,000,000AIDS deaths in 20111,700,000Influenza Epidemic (1918)21,000,000Indonesian Tsunami/Earthquake (2004)230,000Bubonic Plague (1347-51)75,000,000Populations ReviewWhat is growth rate?What is reproductive potential?High reproductive potential?Low reproductive potential?What are the two reasons that cause a population to have exponential growth?What is carrying capacity?What is an example of a limiting factor?How Many People Can Live on Planet Earth?http://www.youtube.com/watch?v=dN06tLRE4WEHuman population growthWaterFood