Intro to Ecology

What is Ecology??

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 & NicheHabitat is the place an organism lives

Niche is an organism’s total way of life

The Nonliving Environment Abiotic factors- the

nonliving parts of an organism’s environment.

Examples:air currents, temperature, moisture, light, Soil nutrients.

The Living Environment

Biotic factors- all the living components of an environment.

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

Abiotic or Biotic?

Biotic

Abiotic or Biotic?

Abiotic

Abiotic or Biotic?

Abiotic

Abiotic or Biotic?

Biotic

Human Impact

What are humans doing to the ecosystems of the world?

What have humans done? 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

What have humans done?

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

Biological magnification

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

Fewer amounts of predators at higher levels means more poison in each organism

Keystone species

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 species disappear

Increase biodiversity

Keystone Species Sea Otters were hunted to near

extinction in the Pacific Ocean until people realized that their disappearance caused everything in their food chain to disappear

Bioindicators

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

Sustainability Means the ability to meet human needs in such

a way that the human population can be maintained indefinitelyTo 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

Growth Rate

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

Can populations grow infinitely? 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

What are limiting factors? Any factor that restrains the growth of a

population. For example…Space, Food, Water, or Soil Nutrients

When limiting factors become scarce, organisms begin to compete for them. In this competition, some will win (survive) and some will lose (die)This can also cause a population to declineNo ecosystem can support an infinite amount

of organisms…eventually there is a limit. When limiting factors run out, carrying capacity

is reached and populations decline

Population Ecology

Population Ecology

Population Ecologists study many factors dealing with population, the three most important are…population density growth rateCarrying capacity

Population Density

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)

Levels of Organization Ecologists have organized

species interactions into different levels

1st Level of Organization

Organism:An individual living thing

2nd Level of Organization

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

3rd Level of OrganizationCommunity:

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

4th Level of OrganizationEcosystem: the

community AND the abiotic factors of an area.

5th Level of Organization 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

If the Earth were an apple, the biosphere would be the skin

Levels of Organization

OrganismPopulationCommunityEcosystem Biosphere

Energy Relationships Vocab

Producers are the autotrophs of an environmentMostly by photosynthesis

Consumers are the heterotrophs of the environment. They can be…Herbivores- which eat producersCarnivores- which eat other consumersOmnivores- which eat producers and

consumers

Energy Relationships Vocab

Primary comsumer- 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

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

Food Chains The arrows DO NOT merely show what

gets eatenThe purpose of the arrows is to show where

the energy is goingScientists 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 Webs

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

Make a food chain from this food web

Food Webs Decomposers are

sometimes shown in food chains and food websEventually all

organisms give their remaining energy to decomposers

Trophic Levels Each organism in a food chain or web

represents a trophic levelThe 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

Trophic Levels 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.

Energy Transfers Producers add biomass (Organic material)

to environmentsThey 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

sunSo, THE SUN IS THE ULTIMATE

SOURCE OF ENERGY IN ALMOST ALL ECOSYSTEMS

Energy Transfers 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

Energy Transfers

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

organic material in their foodOrganisms 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

Stored Energy at each level

Stored Energy at each level

Energy Transfers

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

support the organisms at higher levels

Less organisms at the top means less biomass

Nutrient Cycling

Atoms around today have been the same since the beginning of life on Earth

These atoms are constantly being used, reused, and recycled. (CYCLED)

Theses cycles are called biogeochemical cycles

The Carbon Cycle

CO2 is taken out of the air by plants (photosynthesis)

CO2 is put in the air by burning, decomposition, and respiration

Remember, the organic molecules that make us (proteins, carbs, fats, nucleic acids) are made of carbon, which we get by eating

How are humans overloadingthe carbon cycle?

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.

Water Cycle- important words to know Transpiration- when plants lose water

(usually through stomata) Evaporation- water turns from liquid to

gas Runoff- when water runs across land

(possibly picking up pollutants, like fertilizer)

Nitrogen Cycle

Even though the air is mostly N2 gas, many organisms cannot use it.Without nitrogen, no protein or nucleic

acids! Plants get N with the help of bacteria and

soil/fertilizers Animals get N by eating it When living things die, decomposers return

the nitrogen in their bodies to the soil

Community Ecology

Looks at the interactions of different populations within an ecosystem

Species Interactions In Communities

There are 5 major types of Interactions

1. Predator-Prey

2. Competition

3. Parasitism

4. Mutualism

5. Commensalism

Predator-Prey The prey is the organism that is eaten The predator is the organism that does the

eatingExamples:

Lions eating Zebras Snakes eating Mice Birds eating insects

Predator and Prey Populations rise and fall with

each other

Competition 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

Symbiosis

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

3 typesParasitismMutualismCommensalism

Parasitism 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 mistletoeThe organism that the parasite feeds on is

called the HostThe host is harmed in parasitism.

Mutualism 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 Commensalism is a relationship in which one

species benefits from another species and the other is neither harmed nor helped

Example: Remoras and SharksThe 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 + 0Mutualism + +Parasitism + -

Predator Prey + -Competition - -

Great White Shark eating Seal

Lion eating Zebra

Clown Fish live in Anemone, the anemone is neither harmed nor helped by the fish

The Acacia Tree provides shelter for the ants and the ants protect the tree from other insects

Honey guideThese 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

Tapeworm

Dodder plant- poisons and eventually kills the plant it grows on

Ecological Succession

The gradual, sequential growth of a community is called ecological successionThe first species to grow in succession is

called the pioneer speciesPioneer species are typically small, grow

quickly, good at growing under harsh conditions, and good at dispersing offspring

Primary Succession 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

Primary Succession 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

Primary Succession

Secondary Succession

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

Secondary Succession

When does succession end?

When it reaches a climax communityThis is simply a stable end pointAt this point, the community remains relatively

stable assuming there are no more disturbances

Ecosystem Ecology

Biomes

What is a biome? A very large climatic region that contains a

number of smaller, but related ecosystems in it.

Tundra Found in North Freezing temps for most of the time, little rain 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 Characterized by small plants, like grasses, and

mainly small mammals

Tundra

Anaktuvuk Pass, Alaska

Arctic Fox

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

Tropical Rain Forests Found near the

equator Over 200cm of rain

each year, consistent warm temps

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

Tropical Rain Forests

Rainforest in Malaysia on the island of Borneo

Amazon and Amazon River

Bengal Tiger

Temperate Forests

70-150cm of rain, moderate temperatures, 4 distinct seasons

Can be coniferous or deciduous based on the trees that grow thereConiferous- seeds in cones and tend to

be evergreenDeciduous- Shed their leaves each year

Temperate Forests

Deciduous

CONIFEROUS Rainforest

Coyote

Taiga

Found south of Tundra Also called Boreal Forest Very cold (but warmer than Tundra), long

winters; summers relatively wet and warm Animals in this biome often migrate or

hibernate during winter

Taiga

White Spruce taiga, Denali Highway, Alaska Range, Alaska

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

Bobcat

American Black Bear

Grasslands

3 varieties: Temperate grasslands, savanna, and chaparral

Other names include steppes, prairies, pampas and veldts

25-75 cm rain per year, moderate to warm temps

Characterized by grasses dominating, few or no trees

Grasslands

Steppe

prairie

Mongolian Gerbil

Saker Falcon

Northern Lynx

savanna

Deserts Receive less than 25cm of rain each year Can be hot or cold Temperatures can vary greatly from day to

night (the dirt does not trap heat well, which is what warms ecosystems at night)

Desert Kangaroo RatBobcat

Hot Desert Plant Adaptations

Waxy cuticles Tiny hairs and light greens prevent

some heat absorption Keep stomata half closed or only

take in CO2 at night to avoid water loss

Barrel Cactus

Palo Verde

Hot Desert Animal Adaptations

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

Desert Tortoise

Sonoran Desert ToadThorny Devil

Ocean Zones

Ocean Zones 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

Ocean Zones 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

Estuaries Where rivers meet oceans Salt water mixes with fresh Inhabitants are well adapted to changing

temp and salt conditions

Estuary of Klamath River, Oregon River Nith estuary, Scotland

Lakes 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 Oligotrophic

Not a lot of organic matter and vegetationwaters are clearerStill supports fish and other life

Wetlands

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)