chap 7 ecology

8/11/2019 Chap 7 Ecology

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CHAPTER 7: ECOLOGYBIO091


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Learning objectives At the end of the chapter, students should be able to :

1. State the 5 kingdoms of life with their respectiveexamples

2. Define basic terminologies in ecology.3. Distinguish between inter and intraspecific interaction.

4. Describe community interspecific interactions thatincludes predation, herbivory, disease, parasitism,mutualism and commensalism.

5. Summarize the concept on an energy flow through a

food chain and a food web.6. Explain typical pyramids of numbers and biomass


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5 Kingdom system Organisms can be classified into major groups

called kingdom. Organisms within a kingdom share common

characteristics.

A kingdom is divided into smaller units calledphyla.

A phylum is divided into classes, a class intoorders, an order into families, a family intogenera and a genus into species.

The number of organisms in each leveldecreases from kingdom to species.


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The Five Kingdoms of Life


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Kingdom Monera Monera has only one cell

This cell has no nucleus. Organelles are not bound by a double

membrane. Bacteria.

Examples: Lactobacillus, E. coli andNostoc.


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Kingdom Protists Some protists consist of one cell and some have more

than one cell. The multicellular protists are either simple multicellular

or in colonial form. The cells are eukaryotic cell. Have nuclei and numerous organelles that are

surrounded by membranes. Plant-like protists, such as green algae, have

chloroplasts which allow them to photosynthesise. Example: Algae & amoeba Habitat:

- Aquatic and damp habitats.


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Kingdom Protists

They can either be heterotrophic orautotrophic, or both.

The cells of multicellular protists are notspecialised to perform specific functionswithin the organisms.

Examples of protists are Amoeba sp.,Paramecium sp., Spirogyra sp., andTrypanosoma sp.


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Kingdom Fungi There are few

unicellular fungi butmost fungi aremulticellular.

They absorbnutrients from otherorganisms.

Examples: Mould,mushrooms, yeast.


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Kingdom Fungi

The cells are eukaryotic cell.- They are non-photosynthetic.

- Non-motile.- Produce spores.- They can be parasites, saprophytes or

mutualists.


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Kingdom Plantae

More than 250 000 species. Plants are immobile, multicellular

eukaryotes that produce their food through

photosynthesis. Plant cells are enclosed in cellulose cell

walls.

Some examples of Plantae include varioustypes of moss, ferns, conifers andflowering plants.


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Kingdom Animalia

Animals have more than one cell and their cellshave nucleus.

They get energy by consuming other organisms.

Examples: Invertebrates, reptiles, fish, birds,mammals. Around 800 000 species Multicellular heterotrophic eukaryotes with well-

developed tissues.

Do not have rigid cell walls and chloroplasts thatcharacterise plant cells.

Mostly can move from one place to another.


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Nine phyla of kingdom animalia.1. Porifera Sponges.2. Coelentrata/Cnidaria Hydra3. Platyhelminthes Flatworms ( Taenia,

Planaria)

4. Nematoda Roundworm ( Ascarislumbricoides)5. Annelida Earthworms, leeches.6. Arthropoda Centipedes, milipedes, insects.

7. Mollusca Snails.8. Echinodermata Starfish, sea cucumbers.9. Chordata Crocodile, pigeon, rat.


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Phyla of plantae

2 non vascularP Bryophyta- mossesP. Hepaticophyta- liverwortsP. anthocerophyta- hornworts 2 seedless vascular

P. Ptherophyta- frens, whisk ferns, horsetailP. Lycophyta- club mosses 5 seeded vascularP. Coniferophyta- conifers

P. Cycadiophyta- cycadsP. Gnetophyta- gnetophytaP. Ginkophyta- ginkgoP. Anthhophyta- flowering plants

Gymnosperm


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Kingdom Animalia


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Overview: The Scope of Ecology

Ecology is the scientific studyof the interactions betweenorganisms and the environment

These interactions determinedistribution of organisms andtheir abundance

Ecology reveals the richness of

the biosphere Ecologists work at levels

ranging from individualorganisms to the planet


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Population

A population is a group ofindividuals of the samespecies that is colonizing

an area or habitat Population ecology is a

major subfield of ecologythat deals with thedynamics of speciespopulations and how thesepopulations interact withthe environment


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Community

A community consists agroup of populations ofdifferent species in an

area. Community ecology consists

of the study on number andtypes of species present,relative abundance of eachspecies, interaction amongspecies and communityresilience to disturbances


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Ecosystem An ecosystem consist of all the abiotic factors in

addition to the entire community of species thatexist in a certain area.

The environment is made up of two factors:i. Biotic factors - all living organisms inhabitingthe Earthii. Abiotic factors - nonliving parts of the

environment (i.e. temperature, soil, light,moisture, air currents)


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Ecosystem: Abiotic Factors

Abiotic components are :atmosphere made up of gases and

airbone particles that envelop the Earth.hydrosphere waters of the Earth,

including the ocean, polar ice caps, andother forms of liquid and frozen water.

lithosphere the soil and sediments ofthe Earth s outer, rocky layer.


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Ecosystem

Ecosystems range from a microcosm,such as an aquarium, to a large area suchas a lake or forest

Regardless of an ecosystems size, itsdynamics involve two main processes:energy flow and chemical cycling

Energy flows through ecosystems whilematter cycles within them


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What makes thisecosystem dynamic?


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Symbiosis

Symbiosis is a relationship where two ormore species live in direct and intimatecontact with one another


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Interspecific interactions

Ecologists call relationships between species ina community interspecific interactions

Examples are competition, predation, herbivory,

and symbiosis (parasitism, mutualism, andcommensalism)

Interspecific interactions can affect the survivaland reproduction of each species, and theeffects can be summarized as positive (+),negative ( ), or no effect (0)


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Interspecific interactions Interspecific interactions

Can have differing effects on the populations involved


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Competition

Competition is the interaction among two or moreindividuals that attempt to use the same essentialresource such as food, water, sunlight or living space.

Both organisms are harmed by the interaction (-/-). Bothwould have greater survival, growth, and/or reproductionin the absence of the other competitor.

Can be divided into two: Intraspecific competition- The interaction between

members of the same species . Interspecific competition- The interaction between

members of different species


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Intra-specific competition

According to Darwins theory, geneticvariation can be seen in a giraffepopulation according to the length of theneck where it varied.

Some have longer, intermediate and shortneck.

This increase their chances in surviving,by having longer necks.


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Intra-specific

competition


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A study of southern Utah Gilamonsters found that from late April through late May someshelters were occupied by asmany as six Gila monsters atthe same time.

Male-male combat can beobserved as a test of strengthand endurance.

The loser leave the area, andthe winner is presumed to hasaccess to females


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Competition between species with overlappingniches may lead to competitive exclusion

The concept that no two species with identicalrequirements can occupy the sameecological niche . Eventually , one species willbe excluded by the other as a result of

interspecific competition for a resource in limitedsupply.

*Ecological niche Is the total of an organisms use of the biotic and abiotic resources

in its environment


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Inter-specific competition

Gause Experiments (1934) Paramecium Aurelia and P. caudatum

P. Aurelia has a higher rate of population

increase grows faster and can tolerate higherdensity

When grown alone both survive well andestablished a logistic growth


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When mixed togetherin a fixed food medium(bacteria)

P. caudatum died out P. Aurelia interfered

with the populationgrowth of P. caudatumbecause of its highergrowth rate


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Gause concluded that when two speciescompete for the same limiting resources, onespecies will use the resources more efficiently

and thus reproduce more rapidly than the other.

They cannot live occupy the same niche unlessthey modify their behaviour


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Next he used P. bursaria and P. caudatum. Bothsp. reached stability P. bursaria feeds at thebottom of tube while P. caudatum feed in the

solution

Even though both utilize the same food supply they occupied different part of the test tube

This is called resource partitioning


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This is the way of speciesto reduce competition.

It is called resourcepartitioning , in whichthey evolve differences inresource use

May include timing offeeding, location of

feeding, nest sites


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Flowers of two species of Solanum in Mexico are quitesimilar in areas either one or the other occurs

However, in areas where their distributions overlap, thetwo differ significantly in flower size and are pollinated bydifferent kinds of bees

This can be referred as character displacement


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Allopatric populations ofGeospiza fuliginosa andGeospiza fortis on Los

Hermanos and Daphnehave similar beakmorphologies andpresumably eat similarlysized seeds.However, where twospecies are sympatricon Santa Maria andSan Cristobal, G.

Fuliginosa has ashallower, smaller beakand G. Fortis a deeper,larger one, adaptationsthat favor eatingdifferent -sized seeds


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Inter-specific competition Joseph Connell demonstrated the effects of

competition on niche occupation in barnacles . The concept of niches can be used to restate the

competitive exclusion principle: Two sp ecies canno t

co exis t i f thei r n ic hes are ident ical . Ecologically similar species, however, can coexist ifthere are significant differences in their niches.

Niche - The sum total uses that a species makes of thebiotic and abiotic resources in its environment is referredto as its niche.

An organisms ecological niche is analogous to itsprofession, what it does for a living.


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Inter-specific competition Connel studied Balanus balanoides and Chthamalus

stellatus in the Scottish intertidal zone. These species have a stratified distribution on intertidal

rocks. Chthamalus - inhibit the upper rock

Balanus - inhabit the lower rock When Chthamalus individuals were experimentally

removed, Balanus individuals did not expand into theirsection of the rock. Balanus did not spread higher up the

rocks because it apparently cannot tolerate the stress ofdrying out for long periods.

But, when Balanus individuals were removed,Chthamalus individuals spread into the empty area.


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Balanuss realized niche is thus similar to itsfundamental niche.

In contrast when Balanus was excluded, Chthamalus spread down the rock. The realized niche ofChthamalus in the presence of Balanus is much smallerthan its fundamental niche.

Connells observations showed that althoughChthamalus settled in the lower zone that Balanus smothered or crushed Chthamalus and that the mostmortality occurred during the period of most rapidBalanus growth.

As a result of competition a species fundamental niche ,the niche potentially occupied by that species may bedifferent from its realized niche the niche it actuallyoccupies in a particular environment.


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Predation

Predation is the consumption of one species (the prey)by another (he predator).

It is a (+/-) interaction. Includes animals eating other animals, as well as

animals eating plants. During coevolution between predator and prey, the

predator evolves more efficient ways to catch prey, andthe prey evolves better ways to escape predator.


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Predation

Shark have well developed sense organs that couldlocate prey in water. Electroreceptor on the sharks head detect weak

electrical signals from muscular activity of animals

Rattle snakes have heat-sensing organs besidescapable of killing prey with toxins from being fang


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Predation

A brown pelican are capable of diving into water at thespeed of 72 km/h to catch fish

Orcas (killer whales), which hunt in packs, often herdsalmon or tuna into a cove so that they are easier to

catch. Speed of brown pelican or intelligence of orcas will

increase hunting efficiency


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Yellow crab spider is the same colours thewhite or yellow flowers on which it hides

This camouflage keeps insect from

noticing the spider. There are some animals flee from

predators, some have mechanicaldefences and some associate in groups.

Some animals posess chemical defencesalso exibit aposematic coloration(warning coloration).

Example is poison arrow frog that can

synthesized toxin and display brightwarning coloration.


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Predation

Some animals exhibit cryptic coloration thathelps them hide from predators by blending intotheir surroundings.

Certain caterpillars are the same colour ofleaves or twigs that reside on to avoid beingspotted by prey


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Predation

Mimicry is the similarity of one species to another whichprotects one or both. This similarity can be inappearance, behaviour, sound, scent and even location,with the mimics found in similar places to their models.

Mimicry occurs when a group of organisms , the mimics ,evolve to share common characteristics with anothergroup, the models .

For example, birds that use sight to identify palatable

insects (the mimics), whilst avoiding the noxious models. Two types of Mimicry Batesian and Mullerian


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Predation

In Batesian mimicry, a harmless or edible speciesresembles another species that is dangerous.

Example, harmless scarlet kingsnake looks so much likethe venomous coral snakes that predators may avoid it.


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Predation

In, Mullerian mimicry, different species, all of which arepoisonous, harmfull of distasteful resemble one another. Although their harmfullness protects them as an

individual species, their similarity in appearance worksas an added advantage.

Potential predators can more easily learn a singlecommon aposematic coloration.

Viceroy and Monarch butterflies are thought to be anexample of Mullerian mimicry.


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Predation

Predators also use mimicry to trap/confuse preys. Alligator snapping turtles have tongue that resembles

wriggling worms. They display their tongue a bait or small fish before

snapping them


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Herbivory

Milkweeds produce alkaloid and cardiacglycosides, chemicals that are poisonous to allanimal except for a small group of insects.

Herbivorous animals avoid consuming theseinsects because of accumulation of toxins


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Parasitism

In parasitism, one organism benefit (the parasite)benefits while the other (the host) is harmed.

It is a (+/-) relationship Parasites that lives in the body of their hosts are called

endoparasites e.g: tapeworms and Plasmodium Parasites that feed on the external surface of the host

are called ectoparasites e.g: mosquitoes, thick and lice

Parasites ha e a comple life c cle here in ol ing


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Parasites have a complex life cycle where involvingprimary host and intermediate hosts

E.g: blood fluke


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Parasitism

Parasitic proboscis worm caused their crustacean hoststo move away from their cover to the open

Can be consumed by birds that is their second host


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Disease

Disease causing agents are similar to parasiteby causing a (+/-) relationship. Pathogens are smaller than usual parasites

(invertebrates)and have lethal effects Mostly virus, prions, bacteria(prokaryotes),

protists and fungi.


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Disease

In plants, a popular pathogen caused famine inIreland between 1845 and 1849.

The famine was caused by potato blight, that

almost instantly destroyed the primary foodsource for the majority of the Irish people.


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Disease

West Nile virus mainly infectsbirds, but is known to infecthumans and mammals.

The main route of humaninfection is through the bite ofan infected mosquito.

From 1999 to 2004, they killed

thousands of crows andhuman death increase


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Mutualism

An interspecific interaction that benefits bothspecies (+/+)

A mutualism can be

Obligate , where one species cannot survivewithout the other

Facultative , where both species can survivealone


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Facultative Mutualism

Seen in acacia trees and ants Ants feed in the sugar produced

by nectaries on the tree and onthe protein rich swellings the tip

of the leaflets. Acacia will benefit because ants

attack anything that might harmthe trees such as fungal spores

and vegetation close to the tree.

Mycorrhizae are mutualistic Obligate


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Mycorrhizae are mutualisticrelationship between fungi andthe roots of plants. Occurs in90% of plant families.

The Micorrhizal fungus benefitthe plant by decomposing organicmaterials in the soil and providingwater and minerals such asphosphorus to the plant. It alsoincreases the plant absorptivearea and allows movement oforganic materials from tree to

tree. At the same time, the plant roots

supply sugars, amino acids andother organic materials to the

fungus.

ObligateMutualism


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Commensalism

An interaction thatbenefit one species butneither harm nor helpthe other (+/0)

Cattle egrets feed oninsects out of the grassthat is grazed by

cows/buffalo, thereforethey get food.


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Commensalism

Clown fishes live within the waving mass oftentacles of sea anemones

Most fishes avoid the poisonous tentacles,therefore clown fishes are protected frompredators.


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Commensalism

Epiphytes, e.g some tropical orchids use treesfor support without harm or benefit to the tree.

The epiphyte obtain more light and air in this

manner.


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Commensalism

Remora, a sucker fish, live in close association withshark or the larger fish.

The dorsal fin of the sucker fish is modified to form asucker; it uses this to attach itself to the shark.

The sucker fish is small and does not injure (or benefit)the shark, but envoys the sharks protection and lives onthe food scraps formed as the shark attacks its prey.


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Energy transfer

The structure and dynamics of a community depend onthe extend feeding relationship between organism.

The feeding relationship can be referred as trophicstructure in the community.

A food chain is the flow of energy from one organismto the next.

The transfer of food energy will start from photosyntheticorganism (primary producers) Herbivores (primaryconsumers) Carnivores (secondary and tertiaryconsumers) and ends up with decomposers.


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Energy transfer


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Food Chain

Primary producers or autotrophs arespecies capable of producing complexorganic substances (essentially food)from an energy source and inorganicmaterials. These organisms are typicallyphotosynthetic plants, bacteria or algae.

Organism that get their energy byconsuming organic substances are calledheterotrophs.

Heterotrophs include herbivores , whichobtain energy by consuming live plants ;carnivores which obtain energy fromconsuming live animals.


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Food Chain Detrivores ( earthworms ), scavengers

(hyenas, vultures ) and decomposers (bacteris, fungi ) will be the end trophicstructure in a food chain because theyconsumed dead biomass.

Decomposers return the energy fromfood to the ecosystem by decomposingdead organism thus recycling theirorganic matter.

Most food chain have no more than fouror five links.

There cannot be too many links in asingle food chain because the animals atthe end of the chain would not getenough food (and hence energy) or stayalive.


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Food

Chain


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Trophic structure

Trophic structure is the feedingrelationships between organisms in acommunity

It is a key factor in community dynamics Food chains link trophic levels from

producers to top carnivores


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Trophic structure

Energy transfer between trophic levels istypically only 10% efficient.

Secondary production of an ecosystem is theamount of chemical energy in food converted tonew biomass during a given period of time

When a caterpillar feeds on a leaf, only aboutone- sixth of the leafs energy is used for

secondary production An organisms production efficiency is the

fraction of energy stored in food that is not usedfor respiration


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Trophic

structure

Plant materialeaten by caterpillar

200 J

Feces

Growth (new biomass)

33 J

Cellularrespiration

67 J

100 J


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Food Webs

A food web extends the food chain concept from asimple linear pathway to a complex network ofinteractions.

The earliest food webs were published by Victor

Summerhayes and Charles Elton in 1923 and Hardy in1924.

Summerhayes and Eltons depicted the interactions ofplants, animals and bacteria on Bear Island, Norway.

Therefore, they discovered that food chains are notisolated units but instead re linked together , max 7links


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Food Webs

For example, the Antarctic marine food web startwith the phytoplankton, that serves as food ortwo types of zooplanktons, which arecrustaceans krill and copepods.

Zooplankton will be eaten by various carnivoreslike other carnivorous zooplankton, fishes, birds,seal, squids.

Human is on top, catching whales, fishes andkrills.


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Food Webs

f


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Pyramid of Numbers

A pyramid of numbers shows the number oforganisms at each trophic level in a givensystem.

It represents the number of individual organismsin each trophic level.

d f b


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Pyramid of Numbers

Most food webs have four to five links This is because only 0.1% of the chemical

energy fixed by photosynthesis can flow tothe tertiary consumer.

Top level predators are fairly large animalsat a smaller number

d f b


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Pyramid of Numbers

The dynamics of energy flow throughecosystem Have important implication for the human

population. Eating meat

Is a relatively inefficient way of tapping

photosynthesis production Human may get far more calories by

consuming grains instead of eating meat fromgrain fed-animals

P id f N b


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Pyramid of Numbers

Worldwide agriculture could successfully feed manymore people

If humans all fed more efficiently, eating only plantmaterial.

P id f Bi


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Pyramid of Biomass

In simple counting system, the diagram oforganisms looks unstable.

Another way to do it is to figure out the biomass

at each trophic level. So, rather than the number of individuals (e.g.,

200 trees), the overall mass (weight) oforganisms at that level.

A pyramid of biomass illustrates the totalbiomass at each successive trophic level


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P id f Bi


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Pyramid of Biomass

Biomass is a quantitative estimates of the totalamount of living materials indicating theamount of fixed energy at a particular time.

Biomass may be represented as total volume,dry weight or live weight. Typically, these pyramids show a progressive

reduction of biomass in succeeding trophiclevels.

P id f Bi


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Pyramid of Biomass

Most biomass pyramids show a sharp decreaseat sucessively higher trophic level.

P id f Bi


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Pyramid of Biomass

Certain aquatic ecosystems Have inverted biomass pyramids This is because the phytoplankton quickly grow,

reproduce and quickly consumed by zooplanktoncausing them not able to develop a large populationsize.

E l i l P id


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Ecological Pyramids

An energy level diagram wouldrectify the aquatic community

chart to look like a stablecommunity.

C i


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Comparison


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THE END

chap 7 ecology

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