Ecology

What is Ecology?

• The scientific study of interactions among organisms and their environment or surroundings
• The interdependence of life on earth contributes to an ever changing world

Levels of Organization

(Largest to Smallest)

Biosphere

Biome

Ecosystem

Community

Population

Individual

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Levels of Organization

• Individual: A single organism
• Population: groups of individuals that belong to the same species and live in the same area
• species: a group of organisms that can breed and produce fertile offspring

Levels of Organization

• Community: Different populations that live together in a defined area
• Ecosystem: The community plus their nonliving or physical environment
• Biome: A group of ecosystems that have the same climate and similar dominate communities

Biotic vs. Abiotic

• Biotic factors: All the biological or living influences on organisms within an ecosystem
• Examples: plants, fungus, insects, birds, bacteria

Biotic vs. Abiotic

• Abiotic factors: All the physical or nonliving factors on an environment
• Examples: rocks, water, sunlight, temperature, humidity

The scientific study of interactions among organisms and their environment

1. Species
2. Environment
3. Ecology
4. Community

What is the correct order (smallest to largest)

1. Individual-community-population-ecosystem-biome
2. Individual-population-biome-ecosystem-community
3. Community-population-biome-ecosystem-individual
4. Individual-population-community-ecosystem-biome

An ecosystem includes all the

1. Members of one species
2. Living and nonliving factors in an environment
3. Parts of the earth where life exists
4. Members of a species in the same area

Which level of organization includes all the other levels?

1. Organism
2. Ecosystem
3. Population
4. Community

What is the term for a group of organisms of one type living in the same place?

1. Ecosystem
2. Population
3. Community
4. Species

A group of organisms that can interbreed to produce fertile offspring are called a ______.

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All the living factors in an environment are ______ factors.

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Abiotic factors in an ecosystem can include

1. Plants
2. Animals
3. microorganisms
4. sunlight

Energy flow

• Sunlight is the main source of energy for life on earth.
• Energy flows in one direction from the sun to the producers to the consumers

Energy flow

• Autotrophs use the energy from the environment to create organic molecules (photosynthesis)
• Autotrophs are also called producers since they have the ability to produce their own food

Energy flow

• Animals that cannot produce their own food are called heterotrophs.
• Heterotrophs are also called consumers since they get nutrients from other sources

Types of Heterotrophs

• Herbivores: eat only plants
• Ex: cows, grasshopper, deer
• Carnivores: eat only other animals
• Ex: snakes, tigers, owls
• Omnivores: eat both plants and animals
• Ex: humans, bears, crows

Types of Heterotrophs

• Decomposers: break down organic matter and return nutrients to the soil
• Fungi and bacteria
• Detritivores: a type of decomposer that feeds on dead remains of plants and animals
• Ex: mites, earthworms, snails

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All the energy in an ecosystem starts with the

1. plants
2. sun
3. producers
4. consumers

Individuals that produce their own food are called _______.

1. heterotrophs
2. decomposers
3. consumers
4. producers

Heterotrophs that only eat other animals.

Consumers that eat both producers and other consumers are called____.

Food Chains

• The energy stored by producers is passed through the ecosystem along a food chain
• Food chain: line of organisms which food energy is passed through
• Ex: grass mouse snake hawk
• Only 10% of the energy available in one level moves to the next level
• Ex: 100% 10% 1% .1%

Food webs

• Food webs link all of the food chains in an ecosystem together.

Food webs

• Every individual in a food web is linked to the other individuals either directly or indirectly.

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What happens if all the mice leave this ecosystem?

Food webs

• Each level of a food web is called a trophic level
• Lowest food web level = producers
• 2^nd level = primary consumers (herbivores)
• 3^rd level = secondary consumers
• 4^th level = tertiary consumers
• 5^th level = quaternary consumers

Food webs

5^th level

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4^th level

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3^rd level

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2^nd level

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1^st level

Ecological Pyramids

• A diagram representing the relative amounts of energy, mass or number of individuals at each trophic level.

Ecological Pyramids

Ecological Pyramids

• The lower the trophic level, the more individuals, biomass and available energy
• Ex: there are always more individual producers than there are herbivores (primary consumers)

The energy stored by producers is passed through the ecosystem along a _____.

How much available energy gets passed onto the next level of a food chain?

1. 100%
2. 75%
3. 25%
4. 10%

Which will have the most individuals?

1. algae
2. crayfish
3. minnows
4. ducks

If hunters kill most of the ducks, how does that affect the population of algae and floating plants?

1. increases
2. decreases
3. Remains the same
4. Varies with no pattern

What level consumer are herbivores?

1. primary
2. secondary
3. tertiary
4. quaternary

As you go from the grass to the hawk, the amount of energy ____.

1. increases
2. decreases
3. stays the same
4. goes up then down

Biogeochemical Cycles

• Water cycle (review from t-sci)
• Carbon cycle
• Nitrogen cycle

Water cycle

• Movement of water from the atmosphere to the earth and back to the atmosphere
• Evaporation
• Transpiration
• Condensation
• Precipitation
• Respiration
• Perspiration

1

2

3

4

5

6

1- evaporation

2- transpiration

3- condensation

4- precipitation

5- respiration

6- perspiration

Carbon Cycle

• Process in which carbon is cycled through the biosphere.
• Carbon enters the atmosphere as CO2 through:
• Respiration , combustion, decomposition
• CO2 leaves the atmosphere through
• Photosynthesis

Nitrogen Cycle

• Carried out by bacteria found in the soil and on some plant roots
• Nitrogen Fixation: Changing nitrogen gas from the atmosphere into ammonia
• Nitrification: Changing the ammonia into nitrate compounds the plant can use
• Denitrification: Nitrates are broken down to nitrogen gas

Nitrogen

fixation

nitrification

Denitrification

In the nitrogen cycle, bacteria that live on the roots of plants

1. Break down nitrogen compounds into nitrogen gas
2. Remove nitrogen compounds
3. Change gas into plant proteins
4. Change nitrogen gas into ammonia

Carbon dioxide is released into the atmosphere by

1. Vehicle emissions
2. Photosynthesis and respiration
3. Denitrification
4. Nitrification

Carbon Dioxide is removed from the air by

1. The burning of fossil fuels
2. The burning of trees
3. Plants during photosynthesis
4. Animals during respiration

Community Interactions

• All organisms in a community occupy their own niche.
• The niche is all the physical and biological conditions in which an organism lives and the way it uses those conditions
• No two species can occupy the same niche in the same habitat.

Competition

• Because of limited resources, (food, water, nutrients, light, space) all organisms must compete with each other.
• This often means there are winners and losers

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Predation

• An interaction in which one organism (predator) captures and feeds on another organism (prey)

Symbiosis

• Any relationship in which 2 species live closely together
• 3 types of symbiosis
• Mutualism
• Commensalism
• Parasitism

Mutualism

• Both species benefit.

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• Ex: Flower and a bee
• The flower needs the pollinator to help spread pollen so it can reproduce. The bee gets food by drinking the nectar in the flower

Commensalism

• One species benefits and the other is neither helped or harmed.

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• Ex: Whale and Barnacles
• Barnacles attach to the skin of the whale and benefit from the moving water. No effect to the whale

Parasitism

• One organism lives on or inside the other and harms it
• Ex: Tapeworms and humans, Ticks and dogs

Succession

• Ecosystems are always changing in response to natural and human disturbances. Older species die out and new species move in.

Primary succession

• When there is no nutrients in the soil.
• Have to wait for nutrients in order to sustain life
• Ex: After a volcanic eruption

Secondary Succession

• New life forms after a disturbance where there is still nutrients in the soil
• Can be big or small
• Ex: After a forest fire, or a tree falling over

Pioneer Species

• The first species to colonize an area after an ecological disturbance
• Usually very simple plants like moss and lichens

What is a relationship in which one organism is helped and another organism is neither helped nor hurt?

1. Mutualism
2. Parasitism
3. Competition
4. Commensalism

A bee drinks a flower’s nectar and the flower is pollinated. Both benefit from their relationship. What type of relationship is this?�

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1. Mutualism
2. Parasitism
3. Commensalism
4. Predation

What is a type of symbiosis in which one organism benefits and the other is harmed?

1. Mutualism
2. Parasitism
3. Commensalism
4. Succession

How will an environment respond to natural disturbances, such as fires or hurricanes?

1. Commensalism
2. Competition
3. Parasitism
4. succession

Population Growth

• 3 important factors of population growth
• Geographic distribution: The area inhabited by a population
• Density: The number of individuals per unit area
• Growth rate: How fast or slow the size of the population changes

Population Growth

• 3 Factors affect population size
• The number of births (birth rate)
• The number of deaths (death rate)
• The number of individuals that enter or leave the environment. (immigration and emigration)

Consider the following:

• Would you rather:
• receive a penny a day doubled every day for the month of April
• Receive $10,000 every day for the month of april

Exponential Growth

• Assuming a population has abundant space and food and is also protected from predators and disease, it will experience exponential growth.
• J-shaped

curve

Logistic Growth

• In real life, resources are limited so growth slows as the population reaches the carrying capacity.
• Carrying capacity: The number of individuals an environment can support
• Results in a S shaped curve

Limiting Factors

• Factors that cause the population growth to decrease
• These factors are either density dependent or density independent

Density Dependent Factors

• Only become limiting when the population numbers reach a certain level
• These include:
• Competition
• Predation
• Parasitism
• Disease

Density Independent Factors

• Affect all populations in similar ways regardless of the population size
• These include:
• Unusual weather
• Natural disasters
• Seasonal cycles
• Human activities such as damming rivers or clear cutting forests

Human Population Growth

Human Population Growth

• Human populations growth has accelerated in the last few centuries due to the scientific and industrial revolutions
• Improvements in hygiene
• Increases in food production

Human Population Growth

• Demography is the study of populations
• Demographers try to predict population trends using data
• Age structure
• Survivorship: % of age group likely to survive
• Fertility rates
• Migration (immigration and emigration)
• Life expectancy: average # of years likely to survive

Age structure

• A population with more young people than older people will likely increase in population size
• More old people than young people will see a decrease in population size
• An even distribution of ages will see little or no population growth

Fertility Rates

• Factors most clearly related to decline in birth rates are:
• Increasing education
• Economic independence for women

Fertility Rates

• In developed countries, fertility rate is ~ 1.6 children per woman
• In developing countries, fertility rate is ~ 3.1 children per woman
• The theory is that women learn family planning techniques and learn that they can contribute to their families earning while spending less energy bearing and caring for children

Growing populations may use resources faster than they can be renewed.

• Resources that are most affected are:
• Fuel wood – many of the poorest countries use wood as their main fuel source
• Water
• Arable land – land used to grow crops

• Human population growth does not currently show density effects that typically characterize natural populations.
• Human population growth rate has been growing more than exponentially.
• Limited resources eventually will cause human population growth to slow, but global human carrying capacity is not known.

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Conservation

• Renewable resources can be replenished
• Ex: water, plant products
• Nonrenewable resources cannot be replenished
• Ex: coal, oil, natural gas

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• Preservation is the maintaining or protecting of wildlife.
• Introduction of non-native species into an area:
• increases biodiversity of non-native species
• decreases stability of native species

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• Biggest problem with conservation is cost
• Companies are forced to find new ways of processing and dealing with waste
• these added costs get passed on to the consumer.