1. 7 Billion – Videos 2. 7 Billion – Agree or Disagree 3. Intro to Populations - Notes Populations

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Population: all the members of a species living in the same place at the same time. Understanding Populations

3 words to describe a population: 1. Size – (7 billion people on the planet) 2. Density – (people per square mile) 3. Dispersion – (distribution or arrangement of its individuals within a given amount of space) Even Clumped Random

Density

Dispersion

How Does a Population Grow? Growth rate: change in the size of a population over a given period of time. Positive (+): birth rate > death rate Zero (0): birth rate = death rate Negative (-) = birth rate < death rate Change in population size Births Deaths = -

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 descendents It 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 individuals… Produce more offspring at a time Reproduce more often Reproduce early in life Examples: Insects – can reproduce when they are a few hours or days old Humans – reproduce after a number of years

How Fast Can a Population Grow? Exponential Growth: when populations grow faster and faster Occurs when a population has: Plenty of food and space No 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 Factors Food Water Sunlight (producers) Space Disease Competition Predation

Two Types of Population Regulation Density Dependent Density Independent Same species close together Disease spreads from one to the next Death occurs quickly Portion of a population dies regardless of population density Example: Natural disasters (hurricane)

If humans have no natural predators, how is our population controlled?

Human Carrying Capacity? Current human population: approx 7.12 billion people Ranges estimated from 4-16 billion people Hard to estimate how many people this world can hold Technological innovations Medical breakthroughs

What caused this rapid growth?

What sparked our growth? Industrial Revolution (~1750) Modern medicine (20 th century) Death rates DROPPED due to better care Agricultural Advances Transportation Advances

Human Population Growth Population (in billions) Year Years elapsed between milestones Source: U.S. Census Bureau- World POPclock Projection

What 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 check… 1. What are the limiting factors of the human population? 2. How are we different than other species in regards to population control?

What’s our limiting factor? Disease: Bubonic Plague, AIDS, Flu, Malaria Access to food Access to clean water Competition (a.k.a. War)

EventCasualties American War Deaths, all-time600,000 India Famine ( )3,000,000 AIDS deaths in 20111,700,000 Influenza Epidemic (1918)21,000,000 Indonesian Tsunami/Earthquake (2004)230,000 Bubonic Plague ( )75,000,000

Populations Review 1. What is growth rate? 2. What is reproductive potential? 1. High reproductive potential? 2. Low reproductive potential? 3. What are the two reasons that cause a population to have exponential growth? 4. What is carrying capacity? 5. What is an example of a limiting factor?

How Many People Can Live on Planet Earth? N06tLRE4WE Human population growth Water Food