Populations

What is a population?A group of organisms of one species that can

breed and live in the same place at the same time deer population

CommunityA group of organisms of different species

occupying a particular area, usually interacting with each other and their environment. community of a pondOnly the living organisms

EcosystemAll living organisms (biotic factors) in an area

as well as its nonliving environment(abiotic factors) functioning together as a unit.

Living or nonliving?Biotic-LivingAbiotic-Nonliving

What makes up the ecosystem?Think about the picture you just saw……..

Think about 1 fish-now, what other things would have to join in to make up its population?

What would make up its community?What would make up its ecosystem?

What do organisms need to survive?What are the things that organisms need to

survive in any ecosystem?

How do they get those things?

CompetitionWhen more than one organism tries to get

the same food, shelter, or space, they compete for it

Competition is when organisms are all trying to win the same food, space, shelter or mates

Who would survive?Would it be easier to survive if you were

competing for the same place to live as other populations or if you lived someplace different?

What about food-easier if you ate one type of food or ate a few different things in your ecosystem?

NicheThe specific area where an organism

inhabits. The role or function of an organism or

species in an ecosystemThe interrelationship of a species with all the

biotic and abiotic factors affecting it.

What things could cause an organism not to survive?

Limiting FactorsLimiting Factors (LFs) = things that prevent

a population from growing any larger. THINK CARRYING CAPACITY!

2 types of limiting factorsDensity DependentDensity Independent

Density Dependent Limiting FactorsThese are factors that exist when there are

large numbers of organisms in an areaWhat are some examples?

FoodShelterSpaceWaterOxygenNutrientsYOU CAN RUN OUT OF THEM!!!

Density Independent Limiting FactorsDoesn’t matter if there are a small or large

number of organisms in an areaExamples:

Fire Tornado Earthquake NATRUAL DISASTERS Disease

Carrying CapacityThe highest number of organisms that a

certain environment can hold

Carrying CapacityAs the graph begins, it is

increasing at an exponential growth rate (acceleration)

At the midpoint between 0 and the carrying capacity, the graph hits its fastest growth rate, or inflection point

The line then begins to show logistic growth (deceleration) or growth that slows as it reaches its maximum (carrying capacity

Practice ProblemsA deer population inhabited a local park. The

park has enough food, shelter, water, and space to inhabit 40 deer.

The deer population was 12 deer. Each pair of deer (2) can have one offspring per year. How long will it take for the population to reach carrying capacity?

Draw a graph and show your work

Practice ProblemsRead the graphWhat is the carrying capacity of the population?

When was the first time that was reached?

How many times was the population exactly at its carrying capacity?

How many times was it above? Below?

Increase PopulationsWhat things cause a population to increase?

More food (energy) Less predation More resources (money, jobs) More shelter More females More space

Birth rate = number of births (babies born)

Emigration = people coming into an area

Decrease PopulationsWhat causes a population to decrease?

More predatorsNatural disastersDiseaseLack of food, shelter, space, jobs, waterLack of females

Death Rate = number of deaths (people dying)

Immigration = leaving an area