Ecology Part 2Chapter 5-6

1. Explain and identify the factors that affect population growth. (5.1)

What was our definition of population?

Researchers study populations in the following ways:

Geographic RangeDensity and DistributionGrowth RateAge Structure

Geographic Range

Definition: The area inhabited by a population

Range can differ depending on the speciesBacteria vs. Humans vs. Cod

Density and Distribution

Population Density is the number of individuals per unit area

It is like a class roster, we have so many people in this room at this time.

Populations of different species can be different even in the same environment

Density and Distribution

Distribution is how individuals are spaced out across the range.

The three are Random, Uniform, or Clumped

Growth Rate

Growth rate determines whether the population increases, decreases, or stays the same.

What could lead to increases?Decreases?Staying the same?

Increases Decreases

Birth

Immigration: moving into the area

Death

Emigration: moving out of the area

Age Structure

Age structure is the number of males and females of each age in a population

Why would we need to know this?

2. Distinguish between exponential growth and logistic growth. (5.1)

If you provide a group of animals with food, shelter, healthcare, and everything else they need to survive, how will they grow?

Exponential Growth

Growth pattern where the population reproduces at a constant rate

The larger the population gets, the faster it grows

With unlimited resources, a population will grow exponentially

Reproducing Rapidly (Hours)

Bacteria Graph

Reproducing Slowly (100’s of years)

Graph example

New Environment

Graph example

What did you notice about each situation?

Eventually they all created a “J-shape” curve at the end

This is the key characteristic of the exponential growth curve graph.

Logistic Growth

So what happens if an animal does not have ideal conditions and protection from everything?

It slows or even stops growing!

Logistic growth: occurs when a population’s growth slows and then stops, following a period of exponential growth

What can slow population growth?

All of these contribute to creating the carrying capacity

This makes the line have an “S-shape” curve

OBJECTIVE # 5!!!!!Carrying capacity: the max number of individuals of a particular species that a particular environment can support.

6. Describe the factors that determine a carrying capacity. (Limiting Factors) (5.2)

Limiting factor is a factor (something) that controls the growth of a population

We’ve mentioned one of the types at the end of last chapter…

Limiting factors determine the carrying capacity

Population G.O. from book

7. Compare and contrast density-dependent and density-independent limiting factors. (5.2)

Density-Dependent: operates when population density (# of species in the area) reaches a certain level.

Types of Density-Dependent factors

Competition… Why?More individuals living in the area, the sooner they use up resources which leads to decrease of both species

Parasitism and Disease… Why?The more individuals (hosts), the easier it is for the parasites to spread. This can cause lower births of host and sometimes death from disease

Density-Dependent factors

Overcrowding…. Why?Too many leads to not very many food source, shelters, etc… which will cause lower births and higher deaths

Predator-Prey…. Why?Both predator and prey will go up and down over the course of the years. Each one keeps the other in balance.Easier to look at a graph.

Pred-Prey Graph

Density-Independent Factors

These factors happen to all populations regardless of population size and density.

Can be things like weather conditions (hurricanes, tornadoes, droughts) and natural disasters (wildfires)

11. Describe human activities that can affect the biosphere. (6.1)

Agriculture: produces a dependable supply of food that can be stored for later use.

Critical to our survivalIt has led to doubling the worlds food over 50 years

Impacts natural resources like water and soilHow?

Fertilizers and Farm Equipment use Fossil FuelsWhy is this bad?

Development

The development of cities and housingCities led to suburbs developing on the outside

Why is this bad?

Human communities produce lots of wasteIf not disposed, can affect air, water and soilHousing splits farmland and divides natural habitats

Industry

Provides us with all of our modern gadgets and gizmos

How would this be bad?

Take a lot of energy to produce (burns fossil fuels)Usually discards waste directly in air, water, or soil

12. Distinguish between resource use and sustainable development. (6.1)

Much like our Economy, Ecosystems provide us with “good and services”

This is anything that benefit the human economy

These are classified as renewable resources and nonrenewable resources

Renewable Nonrenewable

Can be produced and replaced by a health ecosystem

Ex: TreesWe can cut one down and another one can grow in its place

Natural processes cannot replenish them within a reasonable amount of time

Ex: Fossil fuels like coal, oil, and natural gas

These are formed from buried organic materials over millions of years.When they are gone, its essentially forever.

Sustainable Development

This provides for human needs while preserving the ecosystems that produce natural resources

What would we want it to look like?No long term damage to soil, water, and climateFlexible to survive environmental stressesIt must no only help us survive, but improve our lives

13. Explain how humans affect soil, water sources, and air sources. (6.2)

Healthy soil helps both agriculture and forestry

Bad things that we can do to the soilDesertification: over farming, overgrazing, seasonal drought, and climate change that turns a farmland into desert.

Deforestation: loss of forestsBad because trees help keep soil in place with roots

Water sources

We need it for: drinking water, industry, transportation, energy, and waste disposal

How we affect it:Pollutants: harmful material that can enter a biosphere

EX: DDT

How we try to fix it:Pollution control, Water Cycle, conservation

Badness of DDT

Air SourcesWe need it for: Breathing, Greenhouse effect

How we affect it:Smog: a gray-brown haze formed by pollutants in airAcid Rain: Burning fossil fuels causes this and will damage buildings and plant lifeGreenhouse GasesParticulates

How we are fixing it:Filters, unleaded gasoline