Organization Response to environment Homeostasis – maintaining an

internal level of stability even though external environment is changing

Energy use Growth and Development Reproduction Changes through time

The study of interactions that take place between organisms and their environment.

It explains how living organisms affect each other and the world they live in.

Habitat is the place an organism lives Niche is an organism’s total way of life

Abiotic factors - the nonliving parts of an organism’s environment.•Examples:air currents, Temperature, moisture, light, Soil nutrients

Biotic factors - all the living components of an environment.

All organisms are affected by both biotic and abiotic factors in their niches

•Ecologists have organized the interactions an organism takes part in into different levels according to complexity.

Organism: An individual living thing

Population: A group of the same species, which live in the same area

Biological Community: All the populations of different species that live in the same place at the same time.

Ecosystem: Populations of organisms that interact with each other in a given area ALONG with the abiotic components of that area.

Biosphere: The portion of Earth that supports life.•It is about 20 km (13 mi) wide from deepest parts of ocean to 8-10 km above the surface•The Earth is 600 times as thick as the biosphere•If Earth was an apple, the biosphere would be the skin

So, from smallest to biggest:•Organism•Population•Community•Ecosystem •Biosphere

Important words to know Transpiration- when plants lose water

(usually through stomata) Evaporation- water turns from liquid

to gas Condensation – Water vapor

condenses into clouds Precipitation – any sort of water

falling from the sky (rain, sleet , snow) Runoff- when water runs across land

Carbon dioxide is a greenhouse gas and traps heat in the atmosphere.

Without it and other greenhouse gases, Earth would be a frozen world.

But humans have burned so much fuel that there is about 30% more carbon dioxide in the air today than there was about 150 years ago. The atmosphere has not held this much carbon for at least 420,000 years according to data from ice cores.

The way that carbon is fixed into an environment – PHOTOSYNTHESIS• From the plants, animals receive carbon (up the food chain – discussed later)

Carbon is released into the atmosphere• Burning of fossil fuels/forest fires/etc• Decomposing matter• Respiration (breathing out CO2)

Even though the air is mostly N2 gas, many organisms cannot use it.

To be used by organisms the nitrogen must be fixed – nitrogen fixation

Without nitrogen, no protein or nucleic acids!

Ways in which nitrogen is “fixed” into an ecosystem:• Lightning strikes• Soil microbes (bacteria that convert nitrogen to

a usable form)• Nodules on the roots of legumes (symbiotic

relationship)• From the plants, animals receive nitrogen (up

the food chain – discussed later) Ways in which nitrogen is released into

atmosphere:• Decomposing matter• Industrial complexes

Population Ecology

Population Ecologists study many factors dealing with population, the three most important are…

•Population density •Growth rate •Carrying capacity

Population density measures how crowded a population is • The population density of the US is about 30 people per square kilometer (0.6 mi2) • In Japan it is 337 people/km2

•(Data from 2003)

Growth rate- the amount by which a population size changes over a given time

In order for a population to grow, the birth rate (number of individuals born) must be greater than the death rate (number that die)

Population size constantly changes in any given population due to changes in growth rates

Population grows by the same amount at regular intervals (week, month, year) producing a straight line when graphed

Ex: population grows by the same amount every month (2,4,6,8,10,12)

X axis is time Y axis is population size

The number of individuals added to the population gets larger during each time interval or generation

Ex: population may grow at pattern such as (1,2,4,8,16,32,64 …)

When plotted on a graph the line looks like the letter “J”

X axis is time Y axis is population size

NOOO!!

Every ecosystem has a Carrying capacity

This is the maximum number of organisms that can be supported in a given habitat.

The carrying capacity of a habitat is based on limiting factors

Used to represent carrying capacity

Typically happens when organisms are introduced to a new ecosystem with few predators

At first population will grow slowly then rapidly

Eventually population will reach the carry capacity and then remain stable at that level

X axis is time Y axis is population size

Density-Dependent• Depends on

population size • Increases in food

competition, disease, predator/prey

• Decrease in living space and available water

Density-Independent • Affects the same

percentage of a population regardless of its size

• Natural disasters such as hurricanes, fires, earthquakes, volcanoes or tsunami destroy a habitat

• Human intervention as burning of fossil fuels increases greenhouse gases linked to global warming, deforestation

Agricultural Revolution - Major period of population growth began when humans started to cultivate crops and domesticate animals

Industrial Revolution – Improved food production and distribution

Health Care – germ theory lead to improved hygiene, better waste removal and water treatment

Plague – disease that greatly reduces the size of population (Black Plague in 1300’s reduced the population in England by 50%)

Famine –a severe food shortage causing starvation and death (Potato Famine of 1840’s/China 1870-1890)

War – death by combat, disease, cut off from food supply (Germany 1618-1648/WWI/WWII)

Community Ecology

•Looks at the interactions of populations within an ecosystem

Species Interactions In Communities

1.Predator-Prey 2. Competition 3. Parasitism 4. Mutualism 5. Commensalism

The prey is the organism that is eaten •The predator is the organism that does the eating

Examples: •Lions eating Zebras •Snakes eating Mice •Birds eating insects

Populations rise and fall with each other

Competition occurs when two or more organisms attempt to use the same limited resource.•A limited resource is any resource that

may run out.•Examples:Hyenas fight with lions over the same animals

Two cacti that are side by side compete for water

Close association between two or more organisms of different species living together•3 typesParasitismMutualismCommensalism

Parasitism is the relationship between a parasite and a host.

A Parasite is an organism that lives in or on another organism and feeds on it without immediately killing it.• Examples: ticks, fleas, blood-sucking

leaches, and mistletoe• The organism that the parasite feeds on is

called the Host• The host is harmed in parasitism.

Mutualism is a cooperative partnership between two species in which both species benefit.• An example is the bacteria in your intestines

and you. Billions of bacteria live in your intestines. They help break down food you would otherwise not

be able to digest. They also produce beneficial substances, such as

Vitamin K for you. In return, you give them a warm, dark, food-rich

environment.

Commensalism is a relationship in which one species benefits from another species and the other is neither harmed nor helped

This is the rarest and strangest type of species interaction• Example: Remoras and Sharks

The remoras attach to the sharks and feed on scraps left over from the sharks meals.

The shark is neither harmed nor helped by this relationship

Relationship Organism #1 Organism #2

Commensalism + 0

Mutualism + +

Parasitism + -

Predator Prey + -

Competition - -

Honey guide: These birds will lead people and other mammals to honey and after the mammal opens the bee hive to get the honey, the bird feeds on the bee larvae

Producers are the autotrophs of an environment •Mostly by photosynthesis

Consumers are the heterotrophs of the environment. They can be… •Herbivores- which eat producers •Carnivores- which eat other consumers •Omnivores- which eat producers and consumers

Primary consumer - eats producer Secondary consumer - eats primary Tertiary consumer - eats secondary Detritivores - (Decomposers) - Break

down complex molecules in dead organic matter into smaller molecules • They are responsible for recycling many

nutrients into the soil

Food Chains- A single pathway of energy relationships among organisms in an ecosystem

The arrows DO NOT merely show what gets eaten• The purpose of the arrows is to show where

the energy is going• Scientists refer to eating as an energy

transfer, because when one organism eats another, the main goal is to get energy from the organism.

• SO, the arrow points at the organism that GETS the ENERGY (the organism doing the eating)

Food chains are a very inaccurate depiction of feeding relationships in an ecosystem…Food webs are more accurate

Food webs are interrelated food chains of an ecosystem

Decomposers are sometimes shown in food chains and food websEventually all organisms give their remaining energy to decomposers

Decomposer – tadpole

Producer – plankton

Consumers - everything except the plankton (including the tadpole)

Each organism in a food chain or web represents a trophic level •The trophic level is an organisms position in a sequence of energy transfers (in a food chain or web) •Notice Higher on the food chain means higher trophic level

Producer Primary Consumer

Secondary Consumer

Tertiary Consumer

•A top level carnivore means that NOTHING in that environment is able to eat it. •Organism CAN be at more than one level

•In this diagram, a fox eats a snake, but it eats insects also, it would be both a secondary and tertiary consumer •In real life, many organisms are at 2 or more levels.

Producers add biomass (Organic material produced by an environment, like glucose) to environments

They are always at the bottom of the food chain or web. • So they are the origin of the energy

BUT…Producers get their energy from the sun • So, THE SUN IS THE ULTIMATE SOURCE OF ENERGY IN ALMOST ALL ECOSYSTEMS

•Energy transfers within an environment are often shown using an Energy Pyramid: • Notice that energy is lost as you move up the pyramid •Notice also that low trophic levels are at the bottom and higher levels are at the top

Very little energy (10%) is transferred when one organism eats another. Why is this? • Not all organisms are eaten at any given level • Consumers cannot break down all of the

organic material in their food • Organisms use the energy they make or

consume for themselves and do not store it, some of the energy organisms consume is lost as heat during digestion

This low rate of energy transfer if the reason that as you move up a food chain, there are less organisms at higher trophic levels •There is not enough energy to support the organisms at higher levels

The tendency of a community to retain relatively constant conditions

Large populations with varying genetics tend to be most stable • For example in a field of corn (which tends to

be genetically similar), if there is an outbreak of a deadly corn plant virus, the community would drastically change (most die out)

• But if the field had many other plants in abundance, it would not change as much

The gradual, sequential growth of a community is called ecological succession

This can occur in areas where no life has been before (primary succession)

This can also occur when there is a disaster that completely wipes out a community (secondary succession)

In both primary and secondary succession there is a specific sequence of growth•The first species to grow in succession is called the pioneer species

•Pioneer species are typically small, grow quickly, good at growing under harsh conditions, and good at dispersing offspring

•No true soil is present before Primary Succession

•Because of this it is slower than secondary

•Occurs on newly exposed or created land-like land under melting ice caps or islands formed by volcanoes

•Lichens are usually the pioneer species•They break down the rocks into dirt and when they die, they leave behind organic material, which will be broken down by decomposers

•This creates soil which is basically dirt, minerals, and organic material•This process takes thousands of years

This happens after an existing community is disrupted by a disturbance like a fire

Soil is already present Grasses and weeds tend to be the

pioneer species After many years bigger plants will

begin to grow This process takes about 100 years

When it reaches a climax community•This is simply a stable end point

•At this point, the community remains relatively stable assuming there are no more disturbances

Ecosystem Ecology

Biomes

A very large climatic region that contains a number of smaller, but related ecosystems in it.

Found in Northern North America, Europe, and Asia

Has permafrost (a permanent layer of frozen soil)

Due to the permafrost and a short growing season, there are few or no trees in the tundra

From right: tundra near Churchill, Manitoba, Canada; tundra in the Arctic National Wildlife Refuge, Alaska

AnaktuvukPass, Alaska

Arctic Fox

Found near the equator Over 200cm of rain each year

This biome gets the most rain and supports the greatest variety of life

Bengal Tiger

Rainforest in Malaysia on the island of Borneo

Amazon and Amazon River

Found all over the world Can be coniferous or deciduous based on the trees that grow there

Coniferous - Bears seeds in cones and tend to be evergreen

Deciduous - Shed their leaves each year

Deciduous

CONIFEROUS

Coyote

Found south of Tundra Also called Boreal Forest Very cold, long winters Animals in this biome often migrate or hibernate during winter

Lakes and other water bodies are very common. The Helvetinjärvi National Park, Finland, is located in the southern boreal forest.

Taiga White Spruce taiga, Denali Highway, Alaska Range, Alaska

American Black Bear

Bobcat

3 varieties: Temperate grasslands, savanna, and chaparral

Other names include steppes, prairies, pampas and veldts

Characterized by grasses dominating, few or no trees

savanna

Saker Falcon

prairie

Steppe

Northern Lynx

Mongolian Gerbil

•Receive less than 25cm of rain each year•Can be hot or cold•Temperatures can very greatly from day to night (the dirt does not trap heat well, which is what warms ecosystems at night)

Desert Kangaroo Rat

Bobcat

•Waxy cuticles •Tiny hairs and light greens prevent some hear absorption•Remember, plants need CO2 to photosynthesize. C3 plants take in CO2 through stomata all day, which causes water loss…

•C4 plants keep stomata half closed•CAM plants only take in CO2 at night

Barrel Cactus

Palo Verde

Desert Tortoise

Thorny Devil

Sonoran Desert Toad

•Animals tend to be small •Some are able to get the water they need from food•Nocturnal-only out at night in hot deserts•Burrowers

Aphotic - no light, no photosynthesis; organisms here typically feed on falling dead organisms from above

Photic - has sunlight Intertidal - area of the shoreline covered during

high tide and exposed during low; has organisms that are adapted to periodic exposure to air

Neritic - shallow water above the continental shelf; most productive zone; upwelling carries nutrients from deep waters making it nutrient rich.; this is where coral reefs form in tropical areas

•Oceanic - deep parts of ocean/open sea; fewer species than neritic, nutrient levels low, ½ the photosynthesis that happens on Earth happens in the ocean; •Pelagic - open ocean•Benthic - ocean floor; diverse life can be found living near sea floor volcanic vents

Estuary of Klamath River, Oregon River Nith estuary, Scotland

•Where rivers meet oceans•Salt water mixes with fresh•Inhabitants are well adapted to changing temp and salt conditions

•Eutrophic •rich in organic matter and vegetation, •murky and have a lot of bacteria which eventually use all of the oxygen and that can cause the animal life to die•Lakes naturally become this way over time

•Oligotrohpic •Not a lot of organic matter and vegetation•waters are clearer•Still supports fish and other life

Areas of land covered in freshwater for at least part of the year

Main types are marshes and swamps Wetlands filter pollutants from water;

they prevent flooding by taking in large amount of water

Las Vegas has wetlands, which is the area that most of our rainwater drains to (which is the reason it stays wet)

Human Impact

What are humans doing to the ecosystems of the

world?

ozone layer - created a hole is this layer that protects us from UV radiation due to Chlorofluorocarbon (CFCs)

greenhouse effect - this NATURAL effect keeps the Earth warm, but due to pollution, humans are amplifying this effect and making it warmer than usual (overloading the carbon cycle with too much CO2, a greenhouse gas)

Smog and acid precipitation are caused by air pollution

All of these things have had a hand in changing ecosystems and communities world wide

Many Ecologist study human impact on communities by looking at: •Biological magnification •Keystone species •Bioindicators

Land and water pollution can be a big problem for many organisms • Chemical that we use on farms and in our

homes can be toxic to wildlife Many chemicals that enter an

ecosystem undergo biological magnification, a process in which chemicals become more concentrated as they move up the food chain

These are species that can affect many other species in a community

When these species become extinct, or scarce, the entire community changes and usually many other species are affected

•When a species of starfish that feeds on mussels was removed from an intertidal zone, the mussel began to dominate and eat other species (decreasing biodiversity)

These are species that are especially sensitive to change

Frogs are bioindicators because they live in or around water (which is where pollutants tend to accumulate) and they absorb gases through their skin

Many people believe that the world wide decline in frog populations is an indicator of population declines in other species

Means the ability to meet human needs in such a way that the human population can be maintained indefinitely • To do this, we need to make sure our resources

(like food, space and water) will always be available

• This includes keeping the Earth healthy and maintaining biodiversity

• Biodiversity - refers to the variety of forms of life in an area

• If we keep doing what we are doing this is not going to happen