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4.2 To Eat or What to Eat . . .

Learning Outcomes:3. Identify the energy sources of different groups of organisms.4. Arrange organisms into a food chain or food web.5. Predict the consequences of food web perturbation.

Reminders: New Group Assignment (#2) on Food Webs will be due Monday Oct 5th

What is Food?

Ecologically, there are two ways of obtaining energy (aka food).

Autotrophs Self- feeders vs Heterotrophs feeding from others

Photoautotrophs obtain energy from the sun creating chemical bonds between carbon atoms forming energy rich sugar molecules

Organisms (mostly from Domain Bacteria and Domain Archaebacteria) called chemoautotrophs obtain energy by performing particular chemical reactions to make organic carbon compounds eg. Bacteria near hydrothermal vents obtain energy from hydrogen sulfide (H2S gas released by the vents).

Heterotrophs are further categorized by their means of acquiring energy.

Decomposers – chemically break down organic material externally and absorb the small chemical compounds QUESTION: What domains (and kingdom) do they come from?(bacteria & fungi)

Detritivores – consume dead organic material typically by fragmenting the material and consuming the small pieces. Decomposers in their guts completely breakdown the organic matter and detritivores absorb some of the excess not used by the decomposers. QUESTION: What type of a relationship is this? Symbiotic & mutualism

Herbivores – consume plants/algae (producers)

Omnivores – consume both producers and other animals

Carnivores – consume other animalsThese organisms are referred to as producers.

These organisms are collectively referred to as consumers.

Carpenter ants consuming wood is an example of A) carnivory

B) omnivory

C) herbivory

D) decomposition

E) detritivory

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The mold on the loaf of bread in your kitchen is an example of . .

A) carnivory

B) omnivory

C) herbivory

D) decomposition

E) detritivory

A bird eating berries, seeds and insects is an example of . .

A) carnivory

B) omnivory

C) herbivory

D) decomposition

E) detritivory

QUESTION: How you define how a tapeworm obtains energy? They live in our intestinal tract and absorb nutrients we have ingested.

A food chain represents a linear series of species feeding on each other.

Grasses Field mice Burrowing owl Badger WolfProducer

1st trophic levelPr1imary consumer

2nd trophic levelSecondary consumer

3rd trophic level

Tertiary consumer4th trophic level

Quaternary consumer

5th trophic level

A deep sea hydrothermal vent food chain

H2S reducing bacteria

Copepod Amphipod Shrimp Octopus

Producer Primary consumer

Secondary consumer

Tertiary consumer

Quaternary consumer

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A food chain also represents the transfer of energy among organisms.

Organisms are not able to use all of what they consume. Why not? QUESTION: What can’t they digest?

Much of what is consumed is excreted as waste.

All organisms die and add to the layer of dead organic material. This in turn is ‘food’ for detritivores and decomposers.

Trophic level refers to the position along a food chain in relation to the producers.

On average there are 2 to 5 species linked in a food chain representing 5 trophic levels.

Longer food chains of 5 to 8 species are found in stable environments, where the populations of each species are less susceptible to elimination.

Most consumers obtain their energy from at least 2 to 3 species of prey. A food web is a visual representation of these multiple links illustrating the interconnections of feed or energy acquisition.

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Building a food webConsider the producers in your community and arrange them at the base of your web. Then add each subsequent trophic level in order above the producers.

Draw arrows to indicate the direction of energy flow. Ensure that the arrow heads are distinctive. The thickness of an arrow can be used to show the most common flow of energy (or food preference).

Be sure to include detritivores and decomposers in your web.

Questions for you to consider:1. If you reduce the number or abundance of producers in a food web, what impact does this have on the subsequent trophic levels?

2. Why is the abundance of the top predators (tertiary consumers) considered an indication of the health or stability of a food web?

3. Why is it important to study an ecosystem thoroughly before introducing a non-native species?

New working groups have been assigned through Vista for your next assignment. These groups will be displayed in class. Meet your new group members at the numbers taped up in the classroom to work through an in-class activity that will help prepare you to do Assignment #2.

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It will be useful to have the following 2 pages with you for this in-class activity:

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Kamloops Bunchgrass Community Food Web

red-bellied clerid beetle Enoclerus sphegeusThis beetle preys upon bark-boring beetles like the mountain pine beetle (Dendroctonus ponderosae). It is 8-12 mm long and is found in pine forests.

badger Taxidea taxusBadgers prey on small mammals such as squirrels, chipmunks, gophers, voles, rats and mice a well as birds, occasionally large insects and also rarely on rattlesnakes. They live in burrows in grassland areas. They have few predators but have been preyed upon by coyotes and cougars while their young have been preyed on by eagles and hawks. Badgers are 60 090 cm long and weigh 7-14kg. There are only ~250 badgers in BC and are considered endangered.

ponderosa pine Pinus ponderosa (includes seeds, seedlings, rotting logs) These trees are a major component of the community but most are infested with mountain pine beetle and are dying. Seeds from the cones are eaten by a number of bird species as well as chipmunks, and squirrels. Small seedlings of this tree may be consumed by voles. Decomposition of dead logs adds nutrients back to the soil of the forest ecosystem.

burrowing owl Athene cuniculariaThis small owl (20 cm tall) lives in burrows originally made by other animals such as badgers or gophers. It preys upon small mammals such as voles, mice, pocket gophers and bats. It also preys on small birds, large insects (> 20 mm), salamanders and toads. It is preyed upon by hawks, coyotes, dogs and other owls. Its young are preyed on by badgers, skunks, foxes, weasels, snakes and raccoons. It is endangered mainly due to habitat loss.

cellulolytic bacteria (many species)These microscopic bacteria generally live in the guts of detritivorous insects and herbivorous animals. Along with cellulolytic fungi and cellulolytic protists they possess enzymes to digest the cellulose found in plant material.

Northern Pacific rattlesnake Crotalus oreganus This is the only rattlesnake in BC and generally quiet and non-aggressive. It has venom sacs associated with its fangs which it uses to immobilize prey. It feeds on shrews, moles, voles, pocket gophers, ground squirrels, chipmunks, marmots, the occasional bird and very rarely other snakes. It is preyed upon by hawks, bears, badgers and skunks.

Rough FescueFestuca scabrellaThis perennial grass (survives over winters) grows in sprawling tufts with a flowering stem of which can grow to a height of 1m. The seeds are consumed by rodents, and birds, while the leaves are grazed on by deer and voles. Rough fescue is more tolerant of wider range of moisture conditions it replaces bluebunch wheat grass as the dominant species at higher altitudes.

chipmunk Eutamias minimusThese small rodents (16-28 cm long) eat nuts, seeds, berries, grasses and occasionally fungi or invertebrates (bugs). It is preyed upon by every carnivore with which it shares the habitat. In the spring when nuts and seeds are scarce it eats green shoots of plants which have overwintered and are just beginning their growth for a new season.

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mountain pine beetle Dendroctonus ponderosaeThe mountain pine beetle (5mm long) bores under the bark of pine trees. There the adult feeds on the phloem (a layer of live tissue which transports sugars) and lays eggs there. The larvae which hatch from the eggs consume the wood of the tree with assistance from microbes in their gut. The beetle also spreads a blue-staining fungus which infects the tree and contributes to killing the tree.

mountain chickadee Poecile gambeliThese small birds (12-14 cm) eat small insects and insect larvae as well as seeds. They are important to BC pine forests because, along with woodpeckers, they consume bark-boring insects. Their most common predators are hawks. Their eggs are consumed by weasels, snakes, chipmunks and squirrels.

bluebunch wheat grass Psuedoroegneria spicatum (includes grass and seeds)This relatively small perennial native grass (40 cm tall) is consumed by many herbivores such as deer, elk moose, rabbits, chipmunks and voles. Some organisms consume the seeds including voles, chipmunks and birds.

red-backed vole Clethrionomys gapperiThis small vole (14cm long) feeds on grasses, shrubs, seeds, berries, roots and occasionally on underground fungi. They are preyed upon by weasels, badgers, hawks, owls and snakes.

Pine mushroom or matsutake Tricholoma magnivelare This highly prized mushroom also has a significant role in the community. It is consumed by rodents such as chipmunks and voles as well as insects (adults and larvae). These mushrooms derive their nutrition by decomposing dead organism material (plant as well as animal).