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Ecology

Study of interactions among organisms…. & between organisms with their environmental factors3-The Biosphere

Biosphere• The portion of the Earth that supports life

• Composed of two parts:

1. Biotic factors – the living organisms that inhabit an environment

• All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection

2. Abiotic factors – the nonliving parts of an organisms environment

• Air currents, temperature, light, moisture

• Have effect on living things and often determine which species can survive in an area

Levels of organization in an organism

• Chemicals make up cells…

• Which make tissues…

• Organs…

• Systems…

• And finally, the individual organism

Levels of organization in ecology

• In Ecology, we begin with the individual and move through the levels to the planet, Earth

Species

• Group of organisms with similar characteristics

• Able to breed and produce fertile VIABLE offspring

Species Hybrid

Populations

• Group of individuals (of the same species) that live in the same area

• Example?

• All the fire ants in a pasture

Community

• Groups of different populations that live together

• Examples?

• All the ants, birds, grass, cows, etc in

a pasture

Ecosystem

• Collection of all organisms (biotic) that live in a particular area, together with their non-living (abiotic) parts of an environment

• Examples of abiotic factors??

• Climate, soil type, amount of rainfall, etc

Southern Pine Ecosystem

Fort Bragg, North Carolina

Community Ecology

• Habitat – a specific place where an organism lives out his life

• Niche – the role an organism

plays in the environment

Symbiotic Relationships – two organisms living

in close association with one another

1. Competition (-/-)• compete for limited resource

• Food, mate, territory

2. Predation (+/-) – Hunt and kill your prey

3. Parasitism (+/-)

4. Mutualism (+/+)• lichens (algae & fungus)

5. Commensalism (+/0)• barnacles attached

to whale

Symbiosis – two organisms living in close association with one another

Mutualism

The act of two organisms utilizing one another. Both thrive and help each other.

Commensalism

The act of one organism utilizing another living organism. One thrives and the other is neither harmed nor helped

Parasitism

The act of one organism feeding upon another living organism. The parasite thrives to the host’s detrimentand the host is harmed.

commensalism

predation competition

mutualism

+/0

+/+

+/-

-/-

Symbiotic Relationships

Herbivores(a.k.a. primary

consumers)

feed directly on

producers

Types of Consumers:

Carnivores (a.k.a.

secondary consumers)

feed on other animals

Types of Consumers:

Omnivores • feed on both plants and

animals

• can be either primary or secondary consumers, depending on food chain

Types of Consumers:

Scavenger

• An animal or other organism that feeds on

dead organic matter

• Decomposers/Saprophyte/Detritivores

• feed on (and recycle) dead or decaying matter

• completing the chain, by returning nutrients needed by producers to the environment

Scavengers eat dead

things but do not recycle

Decomposers feed on dead

things AND recycle them

Types of Consumers:

Energy flow through the biosphere

• Autotrophs (producers) • organisms that make their own food

• Heterotrophs (consumers)• Rely on other organisms for their food supply

AUTOTROPHS

Water + CO2 Sugar + O2

HETEROTROPHS

Sugar + O2 water + CO2

What’s the ultimate source of energy for all life?

Food chain

• Series of steps in which organisms transfer energy by eating and being eaten

• Arrow always points the direction of energy flow…..to the consumer

Food Chain

• The pathway of energy that DECREASES as it passes through the trophic (feeding) levels

• Trophic level of an organism is the position it occupies in a food chain

Food web

• Network of complex interactions, linking all of the food chains together

• Show ALL the possible feeding relationships

• Many connections throughout ecosystem

Ecological Pyramids• Energy

Pyramid

• BiomassPyramid

• Numbers Pyramid

Hawk-eye Question: Why are all three shaped as a pyramid?

Energy

Lost as

Heat

What is the relationship between the numbers of

producers and Consumers?

How does this relate to the energy flow through the

ecosystem?

pyramid of numbers

So fewer and fewer

organisms can be

supported at each level

ONLY 10% of energy is passed on to next levelEnergy Pyramid

Biogeochemical cycles:

• Water (hydrologic) cycle

• Driven by solar energy

• Recycles water, which is primary component of all life

• Phosphorus Cycle • driven by decomposing

bacteria & fungi

• phosphorus is an important component of ATP, Nucleic acids, & phospholipids

Carbon Cycle• The Carbon Cycle is driven

mainly by TWO processes:

• Photosynthesis the process by which producers convert sunlight into a useable form of energy

• Cellular Respiration overall process by which the body gets and uses oxygen and gets rid of carbon dioxide

CO2 in

Atmosphere

CO2 in Ocean

Nitrogen Cycle• driven by decomposition by nitrifying bacteria and fungi

• atmospheric nitrogen must be converted to a usable form that plants can use NITRATE

N2 in Atmosphere

NH3

NO3–

and NO2–

What form of nitrogen can plants use?

• Atmospheric Nitrogen… N2?

• Proteins?

• Amino Acids?

• Ammonia… NH3?

• Ammonium… NH4?

• Nitrite… NO2?

• Nitrate … NO3?

Day 2

Ecological Succession

IV. Ecological Succession

• transition in species composition over time • SLOW process, can take years or decades

• usually occurs after a disturbance

• Two types: Primary and Secondary

Mt. St. Helens

1. Primary Succession

• Takes place over land where there are NO living organisms.

• Ex. Bare rock, volcano created new island

Succession of Species

lichens & mosses grasses

treesbushes & small trees

pioneer species

climax forest

compete well in high sunlight

more shade tolerant species

shade tolerant species

stable community

2. Secondary Succession

• Existing community cleared, but base soil is still intact• Ex. Forest fire, harvesting, hurricane

burning releases

nutrients formerly

locked up in the

tissues of tree

the disturbance

starts the process

of succession

over again

Mt St Helens Vid Clip

Bastrop Fire

Bastrop Fire Vid of Bastrop Sept 2015

IIV. Species diversity• Greater diversity = greater stability

• Greater biodiversity offers:

more food resources

more habitats

more resilience in face of environmental change

Populations• members of the same species that reside in the same

area

Characteristics of populations

a. Geographic distribution:

Where do they live?

b. Density:

How many are found in a given unit of area

c. Growth rate:

How quickly do they grow?

Daisy population

Factors affecting population growth?

1. Birth rate:

number of offspring per time period

2. Death rate:

number of deaths per time period

3. Migration rate

movement in and out of populations in a period of time

• Immigration: in• Emigration: out

Exponential growth

• Occurs when individuals in a population reproduce at a constant rate

• Only under ideal conditions

Exponential growth activity

• White flies have a 21 day life span

• During their life span the female will lay approx. 120 eggs

• Calculate the exponential growth of one pair of flies for 6 generations.

• For this experiment we will assume that no death occurs

Logistic growth• Occurs when a population’s growth rate slows or stops,

following a period of exponential (geometric) growth

• Carrying capacity: largest number

that a given environment

can support

Click image to play video.

Limiting factors• cause population growth to stop

• Density-dependent factors depend upon population size:

• Competition

• Predation

• Parasitism

• Disease

Competition• Occurs when 2 species occupies the same niche &

habitat

• What are some things they compete for?

Competition

• Using this 1990 census map of US population densities, what can one deduce at resource competition between the different parts of the country?

How can competition explain

population size in nonhuman

species?

Predation

• Predator: one that consumes or exploits a particular species for self gain

• Prey: one that is consumed or exploited

• What would you expect to happen to prey populations if the predator numbers increased or if predator numbers decreased?

Figure 5-7 Wolf and Moose Populations on Isle Royale

60

50

40

30

20

10

01955 1960 1965 1970 1975 1980 1985 1990 1995

2000

1600

1200

800

400

0

2400

Moose Wolves

Describe the relationship between the wolf and

moose populations shown in the graph.

Predator-Prey relationships

Parasitism and Disease

• Both deplete the host organism of vital minerals and nutrients to sustain life.

• Death of the organism results in the decline of population size.

Heart worms (roundworms) as

exposed by a veterinarian

Density-independent factors

• Limiting factors on population size,

regardless of the

number of individuals

in the population• Weather

• Natural disaster

• Seasonal cycles

• Human activities (habitat destruction)

Corals that have died from weather

changes, leading to increased

water temperature and pollution.

Day 3

Historical Human Population Growth

Agriculturebegins

Plowingand irrigation

Bubonicplague

IndustrialRevolutionbegins

It took 500,000 years to reach 1 billion

& less than 200 years to reach 5 billion.

What might be some reasons why?

What’s the carrying capacity for the human

population?

What if it’s right here? ---------------------------

But, what if it’s right here? ---------------------------

(We do know it lowers when pollution occurs)

Age structure diagrams (population profiles):

graphs showing numbers of people in different age groups in the population

U.S. Population Rwandan PopulationMales MalesFemales Females

What conclusions can be drawn from these graphs?

Human activities that affect the biosphere

• Hunting& Gathering

• Agriculture

• Industry

• Urban development• Austin Smart Growth Initiative

Types of resourcesNonrenewable resources:

• unable to be replenished through natural means

• Ex: fossil fuels, natural gas

Renewable resources:

• able to be replenished but is not unlimited

• Ex: freshwater

Sustainable development

• A way to use natural resources without causing long term environmental problems

• This plan takes into consideration environmental, economic, and community demands

Problems land resources face

Desertification

• the process of overusing land and drought leading to the formation of arid, desert lands that cannot sustain agriculture

Soil erosion • loss of topsoil layer from over farming (plowing) lands

Deforestation• The process of cutting down (logging) forests for lumber and land.

• Leads to severe erosion during heavy rains.

• Which can lead to permanent changes to local soils and microclimates.

Overfishing• Harvesting fish faster than they can be replaced by

reproduction.

• What happens to aquatic food webs if overfishing continues to occur?

Aquaculture• raising water animals for

human use

• Pictured to the right are tilapia fish farms in Australia that then export the fish to markets.

Air pollution• Combustion of carbon

fuels released nitrogen and sulfur that combine with water to form acid rain.

• Pollutant:

• any harmful substance that enters the biosphere from land, air, or water

Acid rain

Why should we preserve biodiversity?

Biodiversity:

• sum total of genetically based variety of all organisms in the biosphere• Ecosystem diversity• Species

diversity

Why should we preserve biodiversity?

• Biodiversity is one of Earth’s greatest natural resources.

• Species of many kinds have provided us with foods, industrial products, and medicines – including painkillers, antibiotics, heart drugs, antidepressants and anticancer drugs.

Threats to species biodiversity

• Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments.

Threats to species biodiversity

• Endangered: species that is declining in population size

• Extinction: species that disappears from all or part of its range

Endangered status:

Ailuropoda melanoleuca

Dodo Bird

• The dodo has been extinct since the mid-to-late 17th century.

• Its extinction occurred during recorded human history and was directly attributable to human activity

Habitat fragmentation• When land is developed through or around

ecosystems, the species residing within are impacted in what way?

Central Park in New

York City is a perfect

example of habitat

fragmentation.

DDT

• First synthesized in 1874, DDT's insecticidal properties were not discovered until 1939, and it was used with great success in the second half of World War II to control malaria and typhus among civilians and troops.

• After the war, DDT was used as an agricultural insecticide, and soon its production and use skyrocketed

• DDT was banned in most countries in 1972

Biomagnification / BioAccumulation :

• Increasing the concentration of harmful materials up the food chain

Introduced species• Humans transport animal and plant species from one

part of the world to another.

• Many of these species can become invasive. They reproduce rapidly and lack parasites and predators that helped control their populations “back home.”

Nutrias are native

to South America

but have become

pests in coastal US

cities.

Water Hyacinth

Hydrilla

Kudzu

Fire Ants

Conserving Biodiversity

• To conserve biodiversity and multi faceted approach is best:

• Protection of species

• Protection of habitat

• Protection of biodiversity

Conserving Biodiversity Challenges

• Balancing :• Public need and economics

• Public policy

• Conservation

Charting a Course for the Future• Researchers are gathering data to monitor and

evaluate the effects of human activities on important systems in the biosphere.

• Issues:

• Ozone depletion

• CO2 emissions

• Global warming

• Alternative fuels

• Alternative food sources

Ozone depletion

• Ozone: layer of concentrated gas that protects the Earth from harmful UV rays

• O3

• 1970s, scientists found a gap in the ozone layer near Antarctica.

NASA image

Global warming

• Compounding the ozone depletion was the buildup of CFCs (chlorofluorocarbons) from aerosols and AC units with Freon.

• CFCs trap heat, leading to a rise in the global temperature.

Ozone

Click on image to play video.

Value of a Healthy Biosphere

• More complex and diverse ecosystems are the more stable they are.

• Complexity + Diversity = Stability

• All ecosystems play a role in the health of the biosphere.