Slide 1- Population Growth When a population increases in size.

Slide 2 Population Growth Question Population A 2000 = 10 Cats 2010 = 12 Cats 2012 = 16 Cats Population B 2000 = 20 Cats 2010 = 20 Cats 2012 = 20 Cats

Slide 3 Another Population Growth Question Population A 2000 = 10 Cats 2010 = 12 Cats 2012 = 14 Cats Population B 2000 = 20 Cats 2010 = 21 Cats 2012 = 22 Cats

Slide 4 – Types of Graphs Ecologists study graphs to see how population size changes. Graphs are named by how they are shaped! Linear Graph J-Shaped Graph S-Shaped Graph

Slide 5 - Linear Graph Populations would grow at the same rate over time. E.g. $3/Hour Amount that you make every hour doesn’t change!

Slide 6 J-Shaped Graph Looks like a “J” (aka Exponential Growth Graph) Growth exponentially increases! Every hour you would make more and more money!  1 st hour = $3  2 nd hour = 3 2 = $9  3 rd hour = 9 2 = $81  4 th hour = 81 2 = $6561

Slide -7 J-Shaped Graph Question A B

Slide 8 Limiting Factors (aka Resources) What an organisms needs to stay alive. If these are not available, individuals will die!  No Food  Too Hot or Too cold  No shelter  No Water.  Etc.

Slide 9 How do populations grow in the wild? Stage 1 = Grow exponentially. Stage 2 = Too many individuals, resources in short supply. Stage 3 = Population stops growing (levels off) “K” = Carrying Capacity

Slide 10 - Carrying Capacity The # of individuals the environment can support/carry. More Resources = More Births Less Resources = More Deaths

Slide 11 Demography The study of human population size.

Slide12 - Human Population We are still growing exponentially! 1800 = 1 Billion People 2015 = 6 Billion People 2052 = 10 Billion People

Slide 13 - Human Limiting Factors We don’t have as many limiting factors as other species! We have not reached carrying capacity yet! Because we have:  Medicine (get rid of diseases)  Clothing (to keep us warm)  Houses (protect us from weather)  Agriculture (massive amounts of food)

Slide 14 Calculating A Country’s Growth Rate Growth Rate = (Births + Immigration) – (Deaths + Emmigration)  Birth rate: # of Births  Death Rate: # of Deaths  Immigration: Individuals moving in a country.  Emigration: Individuals moving out of a country.

Slide 15 - Doubling Time Time needed for a population to double in size.

Slide 16 - Age Structure % of people in each age group. Countries with high % of young people, will grow faster Countries with high % of old people, will grow slower.

Slide 17 Some populations of species grow faster than others! Fast Life-History Grow fast Slow Life-History Grow slow

Slide 18 Rapid vs. Slow Life History ConditionFast Life HistorySlow Life History ExampleBacteria or BugsAnimals (e.g. Elephant) Body SizeSmallBig Birth to AdultVery Quick (hours to days)Very Slow (Years) Good ConditionsPopulation increases rapidlyPopulation stays the same Bad ConditionsPopulation declines rapidlyPopulation stays the same Life SpanShort (Hours to Days)Long (Years)

Slide 19 - Population Density # of individuals in an area. Density-Dependent Factors  Disease  Competition  Predators  Parasites  Food  Crowding/Stress Density-Independent Factors  Volcanic Eruptions  Temperature  Storms  Flood  Drought  Chemical Pesticides Note: Most are abiotic!

Slide 20 - Patterns of Dispersal Dispersal = movement of species Some like to move close together, far apart, or don’t care either way.

Slide 21 - Crowding and Stress Most organisms get stressed when forced to live close. Symptoms of Stress:  Aggression  Decrease in ability to care for children.  Decreased fertility (ability to have kids)  Lower Immune systems, get sick more often!