ECOLOGY

Chapters 3 -4

WHAT IS ECOLOGY?

Interactions and Independence

Ecology – study of interactions among and between organisms and their environment

Levels of Organization (small to large)

Species – group of organisms that can breed and produce fertile offspringPopulations – groups of the same species that live in the same areaCommunities – groups of different populations (therefore different species) that live in the same area

Ecosystem – collection of all of the organisms that live in a particular place, together with their nonliving environmentBiome – a group of ecosystems that have the same climate and similar dominant communities•Examples:

Biosphere – part of Earth in which life exists including land, water, and air.

Climate

Places on the earth that have different climates typically have different living organisms. Three major climate zones due to latitude and angle of heating (earth’s tilted axis):• Polar• Temperate• Tropical

Sunlight

Some heatescapesinto space

Greenhousegases trapsome heat

Atmosphere

Earth’s surface

Sunlight

Most direct sunlight

Sunlight

Sunlight

Sunlight

90°N North Pole

66.5°N

23.5°N

0°

23.5°S

66.5°S

90°S South Pole

Arctic circle

Tropic of Cancer

Equator

Tropic of Capricorn

Arctic circle

Section 4-1

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Greenhouse Effect Different Latitudes

The World’s Major Land Biomes

Ecological Levels of Organization

Pass It AlongEnergy flows in one direction through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food). Your body gets the energy and materials it needs for growth and repair from the foods you eat.

Energy Flow

Sunlight is the main source of energy for life on Earth.Less than one percent of the sun’s energy that reaches the surface is used by living thingsAutotrophs (producers) – organisms that use either light energy or inorganic chemicals make their own food

Photosynthesis – process in which organisms use light to make their own food (sugar)•Examples: plants, algae, some bacteria and some protists

Chemosynthesis - process in which organisms use inorganic chemicals to make food•Examples: bacteria which live in volcanoes, hot springs, and deep-sea vents

Heterotrophs (consumers) – organisms that must eat and cannot make their own food

Herbivores – eat only plants•Examples

Carnivores – eat only animals•Examples

Omnivores – eat both plants and animals•Examples

Decomposers – break down organic material•Examples

Feeding RelationshipsFood Chain – series of steps in which organisms transfer energy by eating or being eatenFood web – links all of the food chains in an ecosystem Trophic Level – each step in a food chain or food web

What eats what? This is the order:

ProducersPrimary consumersSecondary consumersTertiary consumers

Arrows point the direction the energy or food flows (from food to “eater”).

Section 3-2

A Food Web

Make your own food web

Ecological Pyramid – a diagram that shows the relative amounts of energy or matter contained within each trophic level of a food chain or web

Energy Pyramid - shows the relative amount of energy available at each trophic level.

Energy Pyramid

•Ten Percent Rule - only about 10% of energy available within one trophic level is transferred to next level

•Why this inefficiency? List 3 reasons.

Not all of the caterpillar’s food is converted into biomass or potential energy for a predator.

Biomass Pyramid – shows the total amount of living tissue within each trophic levelPyramid of Numbers – shows the relative number of organisms at each trophic level

ECOLOGICAL PYRAMIDS

Terms to know…

Biotic – biological (living) factors that affect an ecosystemAbiotic – nonliving (physical) factors that affect an ecosystem

Biotic Factors

ECOSYSTEM

Abiotic Factors

Section 4-2

Abiotic and Biotic Factors

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Biotic Factors

ECOSYSTEM

Abiotic Factors

Section 4-2

Abiotic and Biotic Factors

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Niche – full range of physical and biological conditions in which an organism lives and the way the organisms uses those conditions

Bay-Breasted WarblerFeeds in the middlepart of the tree

Yellow-Rumped WarblerFeeds in the lower part of the tree andat the bases of the middle branches

Cape May WarblerFeeds at the tips of branchesnear the top of the tree

Spruce tree

Section 4-2Figure 4-5 Three Species of Warblers and Their Niches

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Interactions in Ecosystems

Organisms not only live together in ecological communities, but they also constantly interact with one another. These interactions, which include predation and competition, help shape the ecosystem in which they live.

Section 4-2

Community InteractionsCompetition—an interaction in which organisms of the same or different species attempt to use a resource in the same place and at the same time.Predation—an interaction in which one organism captures and feeds on another animal

Symbiosis – a relationship in which two species live closely togetherThree types of symbiosis:

mutualism = + + (both benefit)•Examples:

commensalism = + 0 (one benefits, other little or no benefit)•Examples:parasitism = + - (one benefits, other harmed)•Examples:

Termites have bacteria in their guts that help the termites to digest wood. The bacteria get a nice, warm gut in which they can live. What relationship is this?

Some orchids grow on trees to get sunlight in dark forests. The orchid does not hurt the tree. What relationship is this?

Remora

Remora attached to a big fish

Remora attach to big fish or whales and eat the parasites that grow on the big fish’s or whales scales. What relationship is this?

This red, sausage-sized structure is the external portion of an unusual, parasitic barnacle, Briarosaccus callosus, found on many species of king crabs. Here the barnacle is parasitizing a scarlet king crab, Lithodes couesi, collected on Pratt Seamount. The parasite sterilizes its hosts and uses their energy to produce hundreds of thousands of barnacle larvae, which closely resemble the larvae of the more typical acorn barnacles. One of the many unusual features of the barnacle is its bright red color, caused by hemoglobin. The barnacle also induces its crab host to protect it and also assist with larval release. Image courtesy of Tom Shirley

1. The hookworm latches on the walls of the colon with its sharp teeth where it feeds on blood.

2. The tapeworm is the longest parasite. A mature adult can lay one million eggs per day.

3. Tapeworm eggs are embedded in the colon.

4. The roundworm can grow to 20 inches (50 cm) long and lay 200,000 eggs per day.

5. Pinworms migrate outside the colon during the night to lay their eggs around the anus. This causes the nightly itching of many unsuspecting victims.

Ticks suck the blood of animals (including people). What relationship is this?

Mouth of a hookworm

Hookworms live in the intestines of many mammals including humans. They suck blood from your gut and can make you sick. What relationship is this?

Ringworm (top left and bottom right) and athlete’s foot (top right) are both fungi that live off of human skin. They both cause irritation and are very contagious.

What relationships are these?

Pseudoscorpions hitching ride on a fly’s leg, Costa Rica. Pseudoscorpions, tiny relatives of true scorpions, often engage in the practice of phoresy, or hitchhiking. What relationship is this?

A remarkable 3-way mutualism appears to have evolved between an ant, a butterfly caterpillar, and an acacia in the American southwest. The caterpillars have nectar organs which the ants drink from, and the acacia tolerates the feeding caterpillars. The ants appear to provide some protection for both plant and caterpillar. Research of Diane Wagner, American Museum of Natural History Southwestern Research Station

A critical phase in the life cycle of plants is the proper dispersal of its seeds. Many wonderful or strange adaptations have evolved to insure this dispersal. One of these adaptations is the evolution of recuved spines on the seeds or seedpods to attach the seeds to the fur of passing vertebrates who carry the seeds away from the parent plant. In the case of humans, fur is replaced by pants, sweaters, socks, and other pieces of clothing. Plants, therefore, anticipated the invention of velcro from several million years. The plant benefits from the relationship by the dispersal of its seeds. The vertebrates are not affected except, perhaps, by being annoyed.One of the most famous examples are the burdocks, common weeds found along roadsides and in empty lots and fields. The species on the left is the Great Burdock (Arctium lappa). The seed heads (burs) of burdocks long spines with hooked tips. The hooked tips catch onto the hair of passing vertebrates (cows, deer, dogs, humans) and the burs are carried elsewhere until they finally drop off or are pulled off by the carriers.

The anemonefish lives among the forest of tentacles of an anemone and is protected from potential predators not immune to the sting of the anemone. The anemonefish is protected from the sting of the anomone tentacles by a substance contained in the mucous on its skin. Some consider this relationship to be a case of mutualism, claiming that the anemonefish chases away other fish that might prey on the anemone. However this aspect of the relationship is not well documented.

CYCLES OF MATTER

Unlike the one-way flow of energy, matter is recycled within and among ecosystemsBiogeochemical cycles pass molecules around again and again

The CyclesWater CycleCarbon CycleNitrogen CyclePhosphorus CycleWe will focus on the nitrogen

cycle.

The Nitrogen Cycle

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The Nitrogen CycleAll living things need nitrogen as a nutrient. Nitrogen gas makes up 78% of our atmosphere and yet animals and plants cannot use nitrogen gas as a nutrient. So what’s an animal or plant to do?How do animals get nitrogen? They eat protein!How do plants get nitrogen? From bacteria that are in the soil or in the roots of some plants.Plants can only use nitrogen when it is in the form of nitrate (NO3

-) or nitrite (NO2-).

Decomposers breakdown organic material (e.g. dead plants and animals) in the soil. Nitrogen comes from broken down proteins and DNA.Some bacteria live in the soil and help to convert nitrogen into usable forms for plants. Plants absorb this useable nitrogen from the soil into their roots.

Nitrogen Fixation – when nitrogen gas is converted into useable nitrogen by bacteriaSome bacteria actually live inside of the roots of certain plants (like legumes) and can fix nitrogen in the roots.This is like the bacteria that live in our guts and help us to digest food.Legumes include peas, beans, peanuts, soybeans, alfalfa, and clover. So how is this a cycle? Denitrification – some bacteria can convert nitrites back into nitrogen gas which is released into the atmosphere

Root Nodules

Why do farmers sometimes plant legumes and then plow them into the ground instead of harvesting the crop?

Crop rotation and “green manure”

The green manure is sweet clover on this Washington State farm. Every third year clover, a legume, is planted and plowed under. This improves the nitrogen content and physical structure of the soil for growing wheat and corn the other two years of the rotation cycle.

Nutrient LimitingPrimary Productivity – the rate at which organic materials are made by producers (rate of photosynthesis)Primary productivity depends on the availability of nutrients (water, light etc.)What biomes in the world have the highest primary productivity?

Limiting Nutrient – when a single nutrient limits the productivity (limits the photosynthesis) of an entire ecosystemWhat happens if an area like a lake suddenly receives a lot of a limiting nutrient?

When fertilizers enter lakes, streams, rivers, and oceans from runoff they can supply the aquatic ecosystem with an abundance of a limiting nutrient. This excess supply of a limiting nutrient can produce an algal bloom. The algae quickly because it suddenly has an excess of nutrients. The algal bloom can smother and kill other forms of life.

Blooms of algae, like this outbreak of Codium isthmocladum that washed ashore in Florida, choke the sea grass beds, cause oxygen depletion in the water, and result in losses to the recreation and tourism industries.

RED TIDES

RED TIDES

Mount Saint HelensAt 8:32 Sunday morning, May 18, 1980, Mount St. Helens erupted. Shaken by an earthquake measuring 5.1 on the Richter scale, the north face of this tall symmetrical mountain collapsed in a massive rock debris avalanche. Nearly 230 square miles of forest was blown over or left dead and standing. At the same time a mushroom-shaped column of ash rose thousands of feet skyward and drifted downwind, turning day into night as dark, gray ash fell over eastern Washington and beyond. The eruption lasted 9 hours, but Mount St. Helens and the surrounding landscape were dramatically changed within moments.

BEFORE

AFTER

BEFORE AFTER

Some weedy plants recover quickly

Forest blown over

Same forest 9 years later

Same forest 14 years later

Ecological Succession – a series of changes in a community over time in response to natural and human disturbances

As changes occur, older inhabitants die out and new organisms move in.Primary Succession •Occurs where there is no soil

–After a volcanic eruption–Bare rock exposed by glaciers moving

•Pioneer Species – the first species to populate an area (ex. lichens)

Changes in an Ecosystem

•Lichens (made up of a fungus and an alga) can grow on bare rock.–Lichens release chemicals that dissolve and break down rock thus making soil.

•Once there is soil, other organisms come in like mosses and small plants and animals soon follow. Why do animals come after plants?

Secondary Succession•Occurs when life is removed without destroying the soil

•Plowing, fire, deforestation, drought, etc. can all spark secondary succession

•Occurs faster than primary succession. Why?

Aquatic succession• Succession can also occur in aquatic

ecosystems– For example, when a large whale dies,

the carcass attracts scavengers and decomposers (sharks, crabs, and hagfishes). Smaller fishes come later after most of the tissue has been eaten. The decomposition of the whale makes the area high in nutrients for marine worms and other sediment dwellers. Lastly, bacteria decompose the bones, which attracts chemosynthetic bacteria, mussels, crabs, and clams.