2 PopulationsPopulation- A group of organisms of the same species that live in a particular area.Three important characteristics of a population are its geographic distribution, density, and growth rate.
3 POPULATIONSPopulation Growth- the change in the size of a population with time.Population Density- is the number of individuals per unit area.Geographic Density is how the population is distributed.
4 POPULATION SIZE Three factors can affect population size. Number of birthsNumber of deathsNumber of organisms that enter or exit the population
5 POPULATION SIZEImmigration- The movement of organisms into a population.Emigration- The movement of organisms out of a population.
6 POPULATION GROWTHExponential growth- occurs when the individuals in a population reproduce at an ever increasing rate.
7 POPULATION GROWTHLinear Growth- increase of a population at a constant rate.
8 Maintaining a BalanceFor a population to survive, a balance must exist between producers/consumers, predator/prey, growth and decay, water use and rainfall…etc.
9 Limiting FactorsLimiting Factors- Any condition of the environment that limits the size of a population.Some can happen naturally and some are caused by humans.Ex: Food, water, shelter and space availability, Predation, Climate, Disease, Pollution, Competition,….
10 HUMAN IMPACT Humans have disrupted this balance through…. Building of roads, industry, homesPollutionHunting/poachingGlobal Warming, Excess CO2
12 Carrying CapacityThe number of organisms a given ecosystem can support.S-shaped curve
13 Predicting Carrying Capacity Because ecosystems change, carrying capacity is difficult to predict and calculateHowever, islands are the ideal place to study (clear boundaries)
14 Rabbits in Australia no rabbits in native ecosystems of Australia introduced in 1859number increased rapidly plenty of vegetation; no predators; no competitiondisease and starvation caused the rabbit pop. to crashover time, vegetation recovered and rabbit pop. increased againcontinues to increase and decrease, but less dramatically
17 Rabbits reduced Phillip Island to a wasteland Rabbits reduced Phillip Island to a wasteland. Photos: Department of the Environment and HeritageRecovery was spectacular after the rabbits were eradicated Photos: Department of the Environment and Heritage
19 Reindeer near Alaska25 reindeer introduced to one of Pribilof Islands near Alaska in 1911by 1938, herd had grown to 2,000reindeer ate mostly lichens, which grow back very slowlyby 1950, only 8 reindeer alive on the island
22 Predator/Prey This is an example of a predator/prey relationship. As one increases the other will as a result decrease.….which in turns causes the other to decrease.A normal cycle
23 Two Types of Population Regulation Cause of death may be density dependent or density independent
24 Density Dependent Factors Density Dependent Factors have an increasing effect as populations increasesdeaths are caused due to density (population too many)
25 Density Dependent Factors Competition,PredationParasitismDiseaseCrowding
26 Population is growing rapidly and there are limited resources, predation, or disease
27 Density Independent Factors Density Independent Factors are factors that affect a population or cause death regardless of density.Severe weather, natural disasters, etc. cause death that did not result due to density.
28 DEMOGRAPHY DEMOGRAPHY- The study of population. You can study charts of the age structure of a population and determine if it is growing or not.
33 HUMAN POPULATION Currently at 6.5 Billion People Growing Exponentially Industrial Revolution and Agriculture advancements are the reason for the drastic increase since the 1800’sThe population trends differ depending on Developing and Developed Countries.
34 Developed Countries Higher Average Incomes Slower Population Growth Diverse Industrial EconomiesStronger social supportUses a large % of available resourcesEx: US, Canada, Japan, and countries of Western Europe
35 Developing Countries Lower Average Incomes Simpler and agriculture-based economiesRapid Population GrowthUses small % of available resourcesEx: Indonesia andcountries in Africa.