Ecolo

gy

WHAT IS ECOLOGY?

Ecology- the scientific study of interactions between organisms and their environments, focusing on energy transfer

Ecology is a science of relationships

Organism

Population

Community

Biosphere

Ecosystem

Organism - any unicellular or multicellular form exhibiting all of the characteristics of life, an individual.•The lowest level of organization

POPULATION a group of organisms of one species living in the same place at the same time that interbreed

Produce fertile offspring

Compete with each other for resources (food, mates, shelter, etc.)

Community - several interacting populations that inhabit a common environment and are interdependent.

Ecosystem - populations in a community and the abiotic factors with which they interact (ex. marine, terrestrial)

Biosphere - life supporting portions of Earth composed of air, land, fresh water, and salt water.•The highest level of organization

•All organisms found here

II. Biomes and Aquatic Life Systems

A. Biomes:Land portion of the biosphereDistinct climate and specific life-forms

adapted for life within that climate.Climate - long-term patterns of weather is

the primary factor determining the type of life

B. Aquatic life zones:Marine and Freshwater

15,000 ft10,000 ft5,000 ft

Coastalmountainranges

SierraNevadaMountain

GreatAmericanDesert

RockyMountains

GreatPlains

MississippiRiver Valley

AppalachianMountains

Coastal chaparraland scrub

DesertConiferousforest

Coniferousforest

Prairiegrassland

Deciduousforest

Average annual precipitaion

100-125 cm (40-50 in.)

75-100 cm (30-40 in.)

50-75 cm (20-30 in.)

25-50 cm (10-20 in.)

below 25 cm (0-10 in.)

Ecosystem Concepts and Components

Fig. 4.9, p. 76

C. Ecotone• Transitional zone between two

ecosystems• A mixture of species found in both

ecosystems as well as organisms that are unique to the ecotones.

Ecosystem Boundaries: Ecotones

Land zone Transition zone Aquatic zone

Numberof species

Species in land zoneSpecies in aquatic zone

Species in transition zone only

Fig. 4.10, p. 77

List the factors affect the survival of the organisms in this aquarium?

WHAT DO YOU MEAN BY ENVIRONMENT?

The environment is made up of two factors:

• Biotic factors- all living organisms inhabiting the Earth

• Abiotic factors- nonliving parts of the environment (i.e. temperature, soil, light, moisture, air currents)

Abiotic Factors

• The non living factors, called abiotic , are the physical and chemical characteristics of the environment

• Examples: Temperature, humidity, pH, salinity, oxygen concentration, amount of sunlight, available nitrogen, and precipitation

Habitat vs. NicheNiche - the role a species plays in a community; its total way of life

Habitat- the place in which an organism lives out its life

Habitat vs. NicheA niche is determined by the tolerance limitations of an organism, or a limiting factor.

Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

•Each population has a “Range of Tolerance” to abiotic factors.•These are the minimum and maximum levels that can be tolerated by an organism. *Limiting Factors of Water;

D.O. SalinityLight Penetration Nutrients

*Limiting Factors of Land;Precipitation Temp.Latitude Sunlight

A. Major Non-Living Components

Examples of limiting factors -

•Amount of water•Amount of food•Temperature•Amount of space•Availability of mates

Habitat vs. Niche

Popu

latio

n si

ze

Low High Temperature

Zone ofintolerance

Zone ofphysiological stress

Optimum range Zone ofphysiological stress

Zone ofintolerance

Noorganisms

Feworganisms

Lower limitof tolerance

Abundance of organismsFew

organismsNo

organisms

Upper limitof tolerance

Feeding Relationships• There are 3 main types of

feeding relationships1. Producer - Consumer

2. Predator - Prey3. Parasite - Host

Feeding RelationshipsProducer- all

autotrophs (plants), they trap energy from the sun

• Bottom of the food chain

Feeding RelationshipsConsumer- all heterotrophs:

they ingest food containing the sun’s energy

HerbivoresCarnivoresOmnivoresDecomposers

Feeding Relationships

CONSUMERS 1. Primary

consumers• Eat plants• Herbivores

• Secondary, tertiary … consumers

• Prey animals• Carnivores

Feeding RelationshipsConsumer-Carnivores-eat

meat• Predators

–Hunt prey animals for food.

Feeding RelationshipsConsumer- Carnivores- eat

meat• Scavengers

–Feed on carrion, dead animals

Feeding Relationships

Consumer- Omnivores -eat both plants and animals

Feeding Relationships

Consumer- Decomposers

• Breakdown the complex compounds of dead and decaying plants and animals into simpler molecules that can be absorbed

Symbiotic RelationshipsSymbiosis- two species living

together3 Types of symbiosis:1. Commensalism2. Parasitism3. Mutualism

Symbiotic RelationshipsCommensalism-

one species benefits and the other is neither harmed nor helped

Ex. orchids on a treeEpiphytes: A plant, such as a tropical orchid or a bromeliad, that grows on another plant upon which it depends for mechanical support but not for nutrients. Also called xerophyte, air plant.

Symbiotic RelationshipsCommensalism-

one species benefits and the other is neither harmed nor helped

Ex. polar bears and cyanobacteria

Symbiotic RelationshipsParasitism- one species benefits (parasite)

and the other is harmed (host)

• Parasite-Host relationship

Symbiotic RelationshipsParasitism- parasite-hostEx. lampreys, leeches, fleas,ticks, tapeworm

Symbiotic RelationshipsMutualism-

beneficial to both species

Ex. cleaning birds and cleaner shrimp

Symbiotic RelationshipsMutualism-

beneficial to both species

Ex. lichen

• This relationship enables each to tolerate harsh conditions where neither could survive alone. In this partnership, the fungus furnishes the alga with water, prevents overexposure to sunlight, and provides simple mineral nutrients, while the photosynthesizing alga supplies food to the fungus even if no other organic material is available.

Type of relationship

Species harmed

Species benefits

Species neutral

CommensalismParasitism

Mutualism

= 1 species

Trophic Levels

• Each link in a food chain is known as a trophic level.

• Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem.

Trophic LevelsBiomass- the amount of organic

matter comprising a group of organisms in a habitat.

• As you move up a food chain, both available energy and biomass decrease.

• Energy is transferred upwards but is diminished with each transfer.

Trophic Levels

Producers- Autotrophs

Primary consumers- Herbivores

Secondary consumers-small

carnivores

Tertiary consumers-

top carnivores

ENERGY

Pyramid of Energy – Diagram used to show the flow of energy from one trophic level to another.

Ecological Efficiency:• % of usable energy transferred from level to

level• Typically 5-20%• Measured as Biomass – the dry weight of tissue

and other organic matter

The shape of the Pyramid of Energy Flow Explains why:

1.) So few top carnivores2.) Why these species are the first to suffer when

there is disruption3.) Why they are vulnerable to extinction

Trophic LevelsFood chain- simple model

that shows how matter and energy move through an ecosystem

Trophic Levels

Food web- shows all possible feeding relationships in a community at each trophic level

• Represents a network of interconnected food chains

Food chain Food web(just 1 path of energy) (all possible energy

paths)

Nutrient CyclesCycling maintains homeostasis (balance) in the environment.

•5 cycles to investigate:1. Water cycle2. Carbon cycle3. Nitrogen cycle4. Phosphorus5. Oxygen

Water cycle-

•Evaporation, transpiration, condensation, precipitation

Water cycle-

Carbon cycle-

•Photosynthesis and respiration cycle carbon and

oxygen through the environment.

Carbon cycle-

Nitrogen cycle- Atmospheric nitrogen (N2) makes up nearly 78%-80% of air. Organisms can not use it in that form.Lightning and bacteria convert nitrogen into usable forms.

Nitrogen cycle- Only in certain bacteria and industrial technologies can fix nitrogen.Nitrogen fixation-convert atmospheric nitrogen (N2) into ammonium (NH4

+) which can be used to make organic compounds like amino acids.

N2 NH4+

Nitrogen cycle-Nitrogen-fixing bacteria:Some live in a symbiotic relationship with plants of the legume family (e.g., soybeans, clover, peanuts).

Nitrogen cycle- •Some nitrogen-fixing bacteria live free in the soil.

•Nitrogen-fixing cyanobacteria are essential to maintaining the fertility of semi-aquatic environments like rice paddies.

Atmospheric nitrogenLightning

Nitrogen fixing

bacteria

Ammonium Nitrification by bacteria

Nitrites Nitrates

Denitrification by bacteria

Plants

Animals

Decomposers

Nitrogen Cycle

Phosphorus Cycle

Phosphorus moves from phosphate deposited in rock, to the soil, to living organisms, and finally to the ocean.

Oxygen Cycle

• A plant does photosynthesis to let off Oxygen for organisms to use

• The humans use up the oxygen through respiration and let off CO2.

• The CO2 is then passed from the humans to the plants again.

Toxins in food chains- While energy decreases as it moves up the food chain, toxins increase in potency. •This is called biological magnification

Ex: DDT & Bald Eagles

Population Dynamics• The study of short‐ and long‐term

changes in the number of individuals for a given population, as affected by birth, death, immigration, and emigration

• birth, death, immigration, and emigration.

Battle at Kruger

• Kruger National Park is one of the largest game reserves in Africa. It covers an area of 19,485 square kilometres (7,523 sq mi)

• http://www.youtube.com/watch?v=LU8DDYz68kM

I. Population Dynamics

A. Characteristics of a population

1. Size - number of individuals2. Density - number of

individuals per space3. Age Distribution – portions

of individuals of each age

4. Dispersion – spatial patterns of organisms

B. Factors that govern population size

Births

Emigration

Immigration

Deaths

Models for Population Growth RatesA. Exponential Growth Model:

Observed in populations with few or no resource limitations.

Starts slow and then increases “J-shaped curve”

CHOICE B

• $18,446,74 4,073,709,551,615 dollars!!

Exponential Growth

Exponential Growth (J-shape Curve)

Often described in terms of…1. Biotic Potential: How large a population could grow to if there were unlimited

resources

Populations typically can’t grow exponentially forever.

2. Environmental Resistance:All of the living and non-living factors working to hold a population size down.

Carrying Capacity “K”Number of individuals of a given species that can be

sustained in a given space indefinitelyDetermined by biotic potential and environmental resistance

working against each other

2.0

1.5

1.0

.5

Num

ber

of sh

eep

(mill

ions

)

1800 1825 1850 1875 1900 1925

Populations can Crash

• Limiting factors restrain the growth of a population

• As the population grows, competition for resources increases. Thus, reproduction shrinks over time.

• This may lead to species extinction

Reindeer in Alaska

Fig. 9.6, p. 201

2,000

1,500

Num

ber o

f rei

ndee

r

1910 1920 1930 1940 1950

Year

1,000

500

http://www.youtube.com/watch?v=-hO-vCPuuQQ

http://www.youtube.com/watch?v=gfbQA-Krx9Q

What is Ecological Succession?

• Natural, gradual changes in the types of species that live in an area

• Can be primary or secondary • The gradual replacement of

one plant community by another through natural processes over time

Primary Succession• Begins in a place without any

soil: »Sides of volcanoes»Landslides»Flooding

• First, lichens that do not need soil to survive grow on rocks

• Next, mosses grow to hold newly made soil

• Known as PIONEER SPECIES

Pioneer Species

Lichens break down rock to form soil.

Low, growing moss plants trap

moisture and prevent soil

erosion

Primary Succession• Simple plants like mosses and

ferns can grow in the new soil

Primary Succession• The simple plants die, adding

more organic material (nutrients to the soil)

• The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

Primary Succession• These plants die, and they add

more nutrients to the soil• Shrubs and trees can survive

now

Secondary Succession• Begins in a place that

already has soil and was once the home of living organisms

• Occurs faster and has different pioneer species than primary succession

• Example: after forest fires

Climax Community• A stable group of plants

and animals that is the end result of the succession process

• Does not always mean big trees–Grasses in prairies–Cacti in deserts