Chapter 3: The Biosphere

What is ecology?

Ecology• Ecology –study of interactions

among organisms, between organisms, and their environment

• Interdependence – Life depends on other living things and natural resources (air, water, land)

Levels of Organization 1. Species

Individual living thing

Levels of Organization 2. Population

• Groups of individuals of same species in an area.

Levels of Organization 3. Community

• Different populations that live together in an area.

• Several populations interacting together.

• Collection of all organisms (biotic) in a particular place together with the abiotic (physical) environment.

Levels of Organization 4. Ecosystem

Levels of Organization

5. Biomes

• Groups of ecosystems with similar climate and communities.

Levels of Organization 6. Biosphere

• The highest level of organization.

• The portion of the Earth that supports

life.

SPECIES

POPULATION

COMMUNITY

ECOSYSTEM

BIOSPHERE

BIOME

Levels of Organization

BIOSPHERE

BIOME

ECOSYSTEM

COMMUNITY

POPULATION

SPECIES

Biotic and Abiotic Factors• Biotic – living

– Plants, Animals ,Mold, Fungi, Bacteria, Protist

• Abiotic – Nonliving– Sunlight, soil, wind, water,

temperature

Ecological Methods1. Observation –

1st step to designing an experiment

2. Experiment – test hypotheses

3. Modeling – make models based on observation & experiment

• Helps make future predictions

3.1 Review

1. Many populations together is called a…

2. Combination of biotic and abiotic factors in an environment make up the…

3. What’s the different between biotic and abiotic?

Community

Ecosystem

Biotic – living factorAbiotic – nonliving factor

3.1 Review Picture• Pick any animal you want and draw a picture

similar to the one below. Include “species, population, community, and ecosystem”

3.2 ENERGY FLOW (Autotrophs and Heterotrophs)

• One of the most important factors to determine capacity to sustain life is Energy Flow

Autotrophs (producers)• Trap light energy to produce food

– Plants– Some protists– Some bacteria

• Photosynthesis – Converts light into chemical energy

6CO2 + 6H2O C6H12O6 + 6O2

• Chemosynthesis – Converts chemical energy into carbohydrates

SUN

Heterotrophs (consumers)

• Must acquire energy from consuming other organisms– Herbivores – plants– Carnivores – animals– Omnivores – both– Detritivores –

eat dead plants & animals– Decomposers – break down

organic matter

3.2 Review

1. Another name for autotroph is…

2. What are the two processes autotrophs use to make energy?

3. What are the four types of –vores?

Producer

Photosynthesis and Chemosynthesis

Carnivore, herbivore, omnivore, detritivore

3.3 Energy Flow in Ecosystems

• Food Chains and Food Webs

Food Chains and Food WebsSUN Autotrophs Heterotroph

1. Food Chain – shows simple energy transfer

2. Food Web – shows possibilities of energy transfer

Trophic Levels

• Trophic Levels – each step in a food chain/web

T Level 1

T Level 2T Level 3

T Level 4?

Ecological Pyramids

• Ecological Pyramids – shows relative amount of energy at each level (10% rule)

• Biomass – total amount of living tissue within a trophic level

3.3 Review

1. Which is more complex – food chain or web?

2. Grass rabbit fox alligator – Which is T2?

3. What is biomass?

Food web

Rabbit

Amount of living tissue in each trophic level

4.2 Niches and Community Interactions

ToleranceSpecies ability to survive and reproduce under a

range of environmental circumstances.

Intolerance Zone

Habitat

• General place an organism lives.• Determined by species tolerance.

Niche

Range of physical and biological conditions in which a species lives and

the ways the species obtains what it needs to survive and reproduce.

Niches• Resources – Things needed for life

– Plants- sunlight, water and soil nutrients– Animals- nesting, space, shelter, food, places to feed

• Physical resources– Abiotic factors required for survival. – Ex- amphibians lose and absorb water through skin::must

live in moist places.

• Biological resources– Biotic factors required for survival. – E.g. when/how reproduces, food, way obtains food.

Competition

• Different organisms attempting to use essential resources.

• Same resources at same time and place = competition– Intraspecific competition-same species competing– Interspecific competition- different

species competing

What do you think these two males are fighting over?

Competitive Exclusion Principle

-No two species can occupy exactly the same niche at the same time.

-One species will win and survive.-One will lose and die.

Dividing Resources

• Helps determine the number and kinds of species in a community and the niche each species occupies.

Review so far… (14 points)• Pick an animal. Any animal.• On a blank piece paper draw or write a paragraph

using COMPLETE SENTENCES:– It’s habitat– Some things that would give it optimal tolerance.– Some things that would cause the habitat to be

intolerable.– It’s niche (list two physical and two biological factors

it interacts with)– When might it come into competition?– What could it do to divide resources with competition?

Predation, Herbivory, and Keystone Species

Predation

Where one animal (the predator) captures and feeds on

another animal (the prey)

Predation• Predators affect size of prey population

and determine the places prey can live.– E.g. birds can play important role in regulating

mouse population sizes

Herbivores• Herbivory - Animal (herbivore) feeds on

producers (plants) • Affect size and distribution

of plants.• E.g- Many white-tailed

deer are eliminating their favorite food plants across US.

Keystone Species• A single species that can

dramatically change in a community

• Ex- Sea otters eat large amounts of sea urchins, which eat kelp.

• Sea otters almost eliminated by hunting; urchins population increased; ate all the kelp.

• Other organisms also disappeared.

Symbioses

Any relationship in which two species live closely together•Three main classes:

1.Mutualism

2.Parasitism

3.Commensalism

Mutualism

• Relationship in which both species benefit• E.g. – Sea anemone and clownfish • Sea anemone-offers shelter; clownfish protects for

preditors.

ParasitismRelationship where one

organism lives inside or on

another organisms and harms it.

Commensalism

Relationship where one organism benefits and the other is

neither harmed or helped

4.2 Review1. What could be a physical and biological resource

for a flower?

2. When does competition occur?

3. Ants protecting a tree that gives the ants shelter is an example of…

Phys – Sun Bio – Roots, insects, etc.

Need for same resources at same time

Mutualism

Symbiosis Review• A : Find an example of each type of symbiosis and

explain why it is that type.• B: Draw a picture of one type of symbiosis.

Chapter 5Populations

5-1

How Populations Grow

How Populations Grow

• Characteristics of Populations• 4 important characteristics of a population

–Geographic distribution–Density–Growth rate

–Age structure

Geographic Distribution

–Geographic distribution – Area inhabited by a population.

–Ranges can vary enormously in size

Population Density• Population Density - number of

individuals per unit area. • This picture shows the population

density of people.

Populations Growth• Three factors affect population size:

–number of births–number of deaths–number of individuals that

enter or leave the population. * Simply put, a population will increase or decrease

in size depending on how many individuals are added to it or removed from it

Immigration & Emigration• Immigration–movement of individuals into an area

• causes growth. • Emigration–movement of individuals out of an area

• causes decrease.

Age Structure• Number of males and females of

each age a population contains.• Age structure greatly effects reproduction

Exponential Growth• Exponential growth – When the

offspring generation is larger than the generation before.

• Population size will increase if there is abundant space and food, and protected from predators and disease

• Under ideal conditions with unlimited resources.

Logistic Growth• Logistic growth- occurs when

growth slows or stops following a period of exponential growth.

  • As resources decrease,

the growth of a population slows or stops.

• The general, S-shaped curve of this growth pattern, is called logistic growth.

Carrying CapacityMaximum number of

individuals of a particular species that a given environment can support.

1. List the four characteristics of population.

2. What factors can change a population's size?

3. What is carrying capacity?

Review 5.1

Geographic distribution, population density, growth rate, age structure

Birthrate, death rate, immigration and emigration

Max number of a population an environment can support

5.2 Limits to Growth

• Limiting factor – factor that controls the growth of a population.–Density dependent–Density independent

• Limiting factors determine the carrying capacity of an environment for a species.

Density- Dependent Factors

• Limit size when the number of individuals reach a certain level1. Competition for food, water,

space, sunlight, etc.

2. Predation and Herbivory – populations cycle up and down

Wolf/Moose graph

Moose Wolves

Density- Dependent FactorsContinued

3. Disease – the denser the population, the easier it spreads

4. Stress from overcrowding –can lower birth rates, higher death rates, can cause parents to neglect young, lead to emigration

Density -Independent Factors

• Affect all populations regardless of size and density

• Weather, natural disasters, seasonal change, human interventions (dams, logging, housing developments)

1. What are the two types of limiting factors?

2. What are the four density-dependent factors?

3. Define density-independent factors.

Review 5.2

Density-dependent, density-independent

Competition, predation, disease, stress

Affect population regardless of size.

5.3 - Historical Overview– For most of human existence, the

population grew slowly because life was harsh. Food was hard to find. Predators and diseases were common and life-threatening.

Historical Overview– Limiting factors kept human death rates high.

Until fairly recently, only half the children in the world survived to adulthood.

– Because death rates were so high, families had many children, just to make sure that some would survive.

Exponential Human Population Growth

– As civilization advanced, life became easier, and the human population began to grow more rapidly. • What types of things made life easier?

The Predictions of Malthus – Exponential growth cannot continue – Two centuries ago, English economist Thomas

Malthus suggested that only war, famine,and disease could limit human population growth.

– Malthus’s work was vitally important to the thinking of Charles Darwin.

The Demographic Transition

– Three stages – Stage I, birthrates and death rates are

high for most of history.

The Demographic Transition

– In Stage II, advances in nutrition, sanitation, and medicine lead to lower death rates.

– Birthrates remain high• Births exceed deaths• Population increases exponentially.

The Demographic Transition

– During Stage III, as education and living standards increase, families have fewer children; population growth slows.

– When the birthrate meets death rate, growth stops.

The Demographic Transition

– So far, the United States, Japan, and Europe have completed the demographic transition.

– Parts of South America, Africa, and Asia are passing through Stage II.

– A large part of ongoing human population growth is happening in only ten countries, with India and China in the lead.

1. What are three things Malthus suggested would decrease population size?

2. Which demographic stage has advances that result in higher birthrates and lower death rates?

3. In Stage III, why would families have fewer children?

Review 5.3

War, famine, and disease

Stage II

Higher education and living standards