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Chapter 31Chapter 31EcologyEcology

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EcologyEcology

The branch of biology that deals The branch of biology that deals with the interactions between with the interactions between

organisms and the relationship organisms and the relationship between organisms and the between organisms and the

environment.environment.

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SpeciesSpecies

A group of organisms that A group of organisms that can interbreed.can interbreed.

Ex: Ex: Homo sapiensHomo sapiens Homo habilusHomo habilus

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PopulationPopulation

Includes all the members of a Includes all the members of a species found in a given area.species found in a given area.Ex: waterlillies in a pond Ex: waterlillies in a pond

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CommunityCommunityIncludes all the populations in Includes all the populations in

a given area.a given area.ExEx: all plants, animals, and : all plants, animals, and

microorganisms make up a microorganisms make up a pond communitypond community

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EcosystemEcosystem

Includes all the members of Includes all the members of the community plus the the community plus the physical environment in physical environment in

which they live in.which they live in.

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BiosphereBiosphereThe portion of the earth in The portion of the earth in

which life exists.which life exists.The biosphere is composed of The biosphere is composed of

many complex ecosystems many complex ecosystems that include water, soil, and that include water, soil, and

air.air.

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(I) (I) EcosystemEcosystemIs the structural and Is the structural and

functional unit studied in functional unit studied in Ecology.Ecology.

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(A) (A) Requirements for a Stable EcosystemRequirements for a Stable Ecosystem

The ecosystem involves interactions between The ecosystem involves interactions between living and nonliving things. Certain living and nonliving things. Certain requirements must be met for a stable requirements must be met for a stable ecosystem to exist:ecosystem to exist:

1.1. There must be a constant supply of energy There must be a constant supply of energy (sunlight for photosynthesis). (sunlight for photosynthesis).

2.2. There must be living organisms that can There must be living organisms that can incorporate the energy into organic compounds incorporate the energy into organic compounds (food).(food).

3.3. There must be a recycling of materials between There must be a recycling of materials between organisms and the environment.organisms and the environment.

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(B) (B) Abiotic FactorsAbiotic Factors Nonliving factors.Nonliving factors. The abiotic factors of an ecosystem include the The abiotic factors of an ecosystem include the

physical and chemical factors that affect the physical and chemical factors that affect the capacity of an organism to live and reproduce. capacity of an organism to live and reproduce. These factors are:These factors are:

1. Intensity and duration of light1. Intensity and duration of light 2. Temperature range2. Temperature range 3. Amount of moisture3. Amount of moisture 4. Type of substrate4. Type of substrate 5. Availability of inorganic substances and gases5. Availability of inorganic substances and gases 6. pH6. pH

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Limiting FactorsLimiting Factors Determines the types of organisms which may Determines the types of organisms which may

exist in that environment.exist in that environment. Examples areExamples are::

1.1. A low temperature common to northern A low temperature common to northern latitudes determines in part what species of latitudes determines in part what species of plants can exist in that area.plants can exist in that area.

2.2. The amount of oxygen dissolved in a body of The amount of oxygen dissolved in a body of water will help determine which species of water will help determine which species of fish will exist there.fish will exist there.

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(C) (C) Biotic FactorsBiotic Factors Living factorsLiving factors These factors directly or indirectly affect These factors directly or indirectly affect

the environment.the environment. Thus, the organisms, their presence, parts, Thus, the organisms, their presence, parts,

interaction, and wastes all act as biotic interaction, and wastes all act as biotic factors.factors.

These interactions include:These interactions include: 1. Nutritional relationships1. Nutritional relationships 2. Symbiotic relationships2. Symbiotic relationships

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1.1.Nutritional RelationshipsNutritional Relationships

Involves the transfer of nutrients from one Involves the transfer of nutrients from one organism to another within an ecosystem.organism to another within an ecosystem.

In terms of nutrition, organisms are either In terms of nutrition, organisms are either autotrophs or heterotrophs.autotrophs or heterotrophs.

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Types of HeterotrophsTypes of Heterotrophs1.1. SaprophytesSaprophytes- include heterotrophic plants, fungi, and - include heterotrophic plants, fungi, and

bacteria which feed on dead organisms. bacteria which feed on dead organisms. ExEx: mushrooms are saprophytes that feed off dead : mushrooms are saprophytes that feed off dead

plants.plants.2. 2. HerbivoresHerbivores- animals that feed on plants. - animals that feed on plants. ExEx: deer : deer 3. 3. CarnivoresCarnivores- animals that consume other animals. Two - animals that consume other animals. Two

types: types: a) a) predatorpredator – which kills and consume their prey. – which kills and consume their prey. b) b) scavengerscavenger- which feed on the remains of animals they - which feed on the remains of animals they

did not kill. did not kill. 4. 4. OmnivoresOmnivores- animals that consume both plants and - animals that consume both plants and

animals (humans). animals (humans).

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2. 2. Symbiotic RelationshipsSymbiotic Relationships Different organisms may live together in a close Different organisms may live together in a close

association.association. This is known as This is known as symbiosis.symbiosis. There are three types:There are three types: 1. Commensalism 2. Mutualism 3. Parasitism1. Commensalism 2. Mutualism 3. Parasitism

KEYKEY:: + = benefits+ = benefits - = harmed- = harmed

o = not affectedo = not affected

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CommensalismCommensalism

(+ , o)(+ , o) In this relationship, one organism benefits In this relationship, one organism benefits

and the other is not affected.and the other is not affected. ExEx: barnacles on a whale: barnacles on a whale

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MutualismMutualism

(+ , +)(+ , +) In this relationship both organisms In this relationship both organisms

benefit from each other.benefit from each other. ExEx: protozoan living in the digestive : protozoan living in the digestive

tract of termites.tract of termites. Wood eaten by termites is digested Wood eaten by termites is digested

by the protozoan. The nutrients by the protozoan. The nutrients released supply both organisms.released supply both organisms.

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ParasitismParasitism

(+ , - )(+ , - ) In this relationship, the parasite In this relationship, the parasite benefits at the expense of the host.benefits at the expense of the host.

ExEx: athlete’s foot fungus on humans: athlete’s foot fungus on humans

tapeworm and heartworm in dogs.tapeworm and heartworm in dogs.

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(II) (II) Energy Flow RelationshipsEnergy Flow Relationships For an ecosystem to be self-sustaining, For an ecosystem to be self-sustaining,

there must be a flow of energy between there must be a flow of energy between organisms.organisms.

The pathway of energy flow through the The pathway of energy flow through the living components of an ecosystem are living components of an ecosystem are represented by represented by food chainsfood chains and and foodfood webs.webs.

          

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(A) (A) Food ChainsFood Chains Green plants and other Green plants and other

photosynthetic organisms photosynthetic organisms are the organisms in an are the organisms in an ecosystem that can ecosystem that can convert radiant energy convert radiant energy from sunlight into food.from sunlight into food.

A A food chainfood chain involves the involves the transfer of energy from transfer of energy from green plants through a green plants through a series of organisms with series of organisms with repeated stages of eating repeated stages of eating and being eaten.and being eaten.

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(B) (B) Food WebsFood Webs In a natural community, In a natural community,

most organisms eat more most organisms eat more than one species and may than one species and may be eaten, in turn, by more be eaten, in turn, by more than one species.than one species.

Thus, the various food Thus, the various food chains in a community chains in a community are interconnected are interconnected forming a forming a food web.food web.

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There are three basic classes of organisms in There are three basic classes of organisms in a food web:a food web:

1.1. ProducersProducers- include green plants and other - include green plants and other photosynthetic organisms that synthesize the organic photosynthetic organisms that synthesize the organic nutrients that supply energy to other members in the nutrients that supply energy to other members in the community.community.

2.2. ConsumersConsumers- include all heterotrophic organisms. - include all heterotrophic organisms. Organisms that feed on green plants are Organisms that feed on green plants are primary primary consumersconsumers, or herbivores. , or herbivores. Secondary consumersSecondary consumers, or , or carnivores, feed on other consumers. carnivores, feed on other consumers.

3.3. DecomposersDecomposers – are the organisms (saprophytes) that – are the organisms (saprophytes) that break down wastes and dead organisms so that break down wastes and dead organisms so that chemical materials are returned to the environment chemical materials are returned to the environment for use by other living organisms.for use by other living organisms.

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DecomposersDecomposers

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(C) (C) Pyramid of EnergyPyramid of Energy The greatest amount of energy The greatest amount of energy

in a community is present in the in a community is present in the organisms that make up the organisms that make up the producer level.producer level.

Only a small portion of this Only a small portion of this energy is passed on to primary energy is passed on to primary consumers, and only a smaller consumers, and only a smaller portion is passed on to portion is passed on to secondary consumers.secondary consumers.

A A pyramid of energypyramid of energy can be can be used to illustrate the loss of used to illustrate the loss of usable energy at each feeding usable energy at each feeding level.level.

     

                                      

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(III) (III) Cycle of MaterialsCycle of Materials In a self-sustaining ecosystem, various In a self-sustaining ecosystem, various

materials are recycled between organisms and materials are recycled between organisms and the abiotic environment.the abiotic environment.

The recycling process allows materials to be The recycling process allows materials to be used over and over again.used over and over again.

Three examples are:Three examples are:

1. Carbon-Hydrogen-Oxygen cycle1. Carbon-Hydrogen-Oxygen cycle

2. Water cycle2. Water cycle

3. Nitrogen cycle3. Nitrogen cycle

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Carbon-Hydrogen-Oxygen CycleCarbon-Hydrogen-Oxygen Cycle

Carbon, hydrogen, Carbon, hydrogen, and oxygen are and oxygen are recycled through the recycled through the environment by the environment by the processes of processes of respirationrespiration and and photosynthesis.photosynthesis.

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Water CycleWater Cycle Here water moves between the earth’s surface and the Here water moves between the earth’s surface and the

atmosphere.atmosphere. EvaporationEvaporation- liquid water on earth’s surface changes to gas by - liquid water on earth’s surface changes to gas by

the process of evaporation and enters the atmosphere in the the process of evaporation and enters the atmosphere in the form of form of water vapor.water vapor.

CondensationCondensation- water vapor is returned to liquid state and falls - water vapor is returned to liquid state and falls as precipitation.as precipitation.

Some water vapor is added to the atmosphere by Some water vapor is added to the atmosphere by aerobic aerobic respirationrespiration in plants and animals and by in plants and animals and by transpirationtranspiration in in plants.plants.

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Nitrogen CycleNitrogen Cycle Nitrogen is needed by all living things because it is part Nitrogen is needed by all living things because it is part

of the structure of amino acids and proteins.of the structure of amino acids and proteins. In this cycle, nitrogenous wastes and the remains of dead In this cycle, nitrogenous wastes and the remains of dead

organisms are converted by decomposers and soil organisms are converted by decomposers and soil bacteria into compounds that can be used by autotrophs.bacteria into compounds that can be used by autotrophs.

The Nitrogen cycle includes the following reactions:The Nitrogen cycle includes the following reactions:

1. Atmospheric nitrogen is converted into nitrates by the 1. Atmospheric nitrogen is converted into nitrates by the nitrogen-fixing bacteria.nitrogen-fixing bacteria.

2. Nitrates are used by plants for the synthesis of 2. Nitrates are used by plants for the synthesis of proteins.proteins.

3. Animals feed on plants and convert plant proteins to 3. Animals feed on plants and convert plant proteins to animal proteins. animal proteins.

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4. Nitrogenous wastes and dead organisms are 4. Nitrogenous wastes and dead organisms are decomposed and ammonia is released.decomposed and ammonia is released.

5. Ammonia is converted to nitrates by nitrifying 5. Ammonia is converted to nitrates by nitrifying bacteria.bacteria.

6. Denitrifying bacteria break down nitrogen compounds 6. Denitrifying bacteria break down nitrogen compounds and release nitrogen gas into the atmosphere.and release nitrogen gas into the atmosphere.

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(IV) (IV) Ecosystem FormationEcosystem Formation

Ecosystems tend to change over a Ecosystems tend to change over a long period of time until a stable long period of time until a stable

ecosystem is formed.ecosystem is formed.Both the living and nonliving Both the living and nonliving

parts of an ecosystem change.parts of an ecosystem change.

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(A) (A) Ecological SuccessionEcological Succession The replacement of one kind of community with The replacement of one kind of community with

another is called another is called ecological succession.ecological succession. The kind of stable ecosystem that develops in a The kind of stable ecosystem that develops in a

particular geographical area depends on climate.particular geographical area depends on climate. Pioneer organismsPioneer organisms- are the first plants to - are the first plants to

populate an area. Lichens and algae may be populate an area. Lichens and algae may be pioneer organisms on bare rock.pioneer organisms on bare rock.

Climax CommunitiesClimax Communities- Succession ends with the - Succession ends with the development of a climax community in which the development of a climax community in which the populations of plants and animals exist in populations of plants and animals exist in balance with each other and the environment.balance with each other and the environment.

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(B) (B) CompetitionCompetition1.1. Different species living in the same environment, or Different species living in the same environment, or

habitathabitat, may require the same resources. When the , may require the same resources. When the resources are limited, competition occurs among the resources are limited, competition occurs among the species.species.

2.2. CompetitionCompetition- is the struggle between different species - is the struggle between different species for the same limited resources. The more similar the for the same limited resources. The more similar the needs of the species, the more intense the competition.needs of the species, the more intense the competition.

3.3. Each species occupies a Each species occupies a nicheniche in the community. A in the community. A niche is the role the species plays, and includes the type niche is the role the species plays, and includes the type of food it eats, where it lives, where it reproduces, and of food it eats, where it lives, where it reproduces, and its relationships with other species.its relationships with other species.

4.4. When two different species compete for the same niche When two different species compete for the same niche in a community, the weaker species is usually in a community, the weaker species is usually eliminated establishing one species per niche in a eliminated establishing one species per niche in a community.community.

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Graphs showing competition between two species of Paramecium. Since each population alone prospers (top two graphs), when they are in a competition

situation one species will win, the other will lose (bottom graph).

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(C) (C) BiomesBiomes The earth can be divided into broad geographic regions The earth can be divided into broad geographic regions

by climate.by climate. The kind of climax ecosystem that develops in these The kind of climax ecosystem that develops in these

regions are called regions are called biomes.biomes. Biomes can be terrestrial or aquaticBiomes can be terrestrial or aquatic..

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TundraTundra Permanently Permanently

frozen subsoil.frozen subsoil. Plants consist of Plants consist of

lichens, mosses, lichens, mosses, and grasses.and grasses.

Examples of Examples of animals consist of animals consist of caribou and snowy caribou and snowy owls.owls.

                           

                  

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TaigaTaiga Long severe Long severe

winters.winters. Summers with Summers with

thawing subsoil.thawing subsoil. Major plants are Major plants are

conifers.conifers. Animals consist of Animals consist of

the moose and the moose and black bear.black bear.

                                   

          

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Temperate DeciduousTemperate Deciduous Moderate Moderate

precipitation.precipitation. Cold winters with Cold winters with

warm summers.warm summers. Plants consist of Plants consist of

deciduous trees deciduous trees (maple, oak, and (maple, oak, and beech).beech).

Some animals are Some animals are snakes, monkeys, snakes, monkeys, and the leopard.and the leopard.

                    

                         

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Tropical ForestTropical Forest Heavy rainfall, Heavy rainfall,

constant warmth.constant warmth. Consist of many Consist of many

species of broad-leaf species of broad-leaf plants.plants.

Animals are Animals are pronghorn antelope, pronghorn antelope, prairie dog, and the prairie dog, and the bison.bison.

                                

             

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DesertDesert Sparse rainfallSparse rainfall Extreme daily Extreme daily

temperature temperature fluctuations.fluctuations.

Plants consist of Plants consist of drought-resistant drought-resistant shrubs and succulent shrubs and succulent plants.plants.

Examples of animals Examples of animals are kangaroo rat and are kangaroo rat and lizards.lizards.

                             

                

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Biome ReviewBiome Review

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V.V. Biosphere Biosphere and and

HumansHumans

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Past and PresentPast and Present

Humans, in exercising a unique Humans, in exercising a unique and powerful influence on the and powerful influence on the physical and living world, have physical and living world, have modified their environment.modified their environment.

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1. 1. Negative AspectsNegative Aspects Natural systems have been upset because humans have Natural systems have been upset because humans have

not realized that they not only influence other not realized that they not only influence other individuals, other species, and the nonliving world, but individuals, other species, and the nonliving world, but are, in turn, influenced by them.are, in turn, influenced by them.

Although most ecosystems are capable of recovering Although most ecosystems are capable of recovering form the impact of minor disruptions, human form the impact of minor disruptions, human activities have sometimes increased the magnitude of activities have sometimes increased the magnitude of such disruptions so as to bring about a more lasting such disruptions so as to bring about a more lasting and less desirable change in the environment upon and less desirable change in the environment upon which all life depends.which all life depends.

Such disruptions will directly affect at least one of the Such disruptions will directly affect at least one of the components of an ecosystem and this, in turn, may components of an ecosystem and this, in turn, may affect the remaining components.affect the remaining components.

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Examples of Negative AspectsExamples of Negative Aspects::

a) Human Population Growtha) Human Population Growthb) Human Activitiesb) Human Activities - Overhunting- Overhunting - Importation of Organism- Importation of Organism - Exploitation- Exploitation - Poor Land Use Management- Poor Land Use Management - Technological Oversight- Technological Oversight

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a) Human Population Growtha) Human Population Growth The total population of The total population of

humans has risen at a humans has risen at a rapid rate, partly because rapid rate, partly because of the removal of natural of the removal of natural checks on the population, checks on the population, such as disease.such as disease.

This continued increase This continued increase in the human population in the human population has far exceeded the food-has far exceeded the food-producing capacities of producing capacities of many ecosystems of the many ecosystems of the world.world.

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b) Human Activitiesb) Human Activities Some human activities Some human activities

have led to the extinction have led to the extinction or endangerment of or endangerment of numerous species of plants numerous species of plants and animals as well as and animals as well as producing less favorable producing less favorable living conditions for many living conditions for many species, including humans.species, including humans.

The following slides The following slides represent a list of human represent a list of human activities that negatively activities that negatively affect our environmentaffect our environment..

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1. Overhunting1. Overhunting Uncontrolled hunting, Uncontrolled hunting,

trapping, and fishing trapping, and fishing still occur in many still occur in many parts of the world.parts of the world.

The extinction of the The extinction of the dodo bird and the dodo bird and the passenger pigeon passenger pigeon resulted from such resulted from such activities.activities.

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2. Importation of Organisms2. Importation of Organisms Humans have Humans have

accidentally and/or accidentally and/or intentionally imported intentionally imported organisms to areas organisms to areas where they have no where they have no natural enemies leading natural enemies leading to the disruption of to the disruption of existing ecosystems.existing ecosystems.

Examples include the Examples include the Japanese beetle and the Japanese beetle and the Gypsy moth.Gypsy moth.

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3. Exploitation3. Exploitation The exploitation of The exploitation of

wildlife for their wildlife for their products and pet trade products and pet trade has led to threatened has led to threatened populations and populations and ecosystem disruptions.ecosystem disruptions.

Examples include: the Examples include: the African elephant—African elephant—ivory; the Colombian ivory; the Colombian parrot—pet trade; parrot—pet trade; Tropical rain forest—Tropical rain forest—plywood. plywood.

                            

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44. Poor Land Use Management. Poor Land Use Management Increased urbanization/Increased urbanization/

suburbanization claims suburbanization claims increasing amounts of increasing amounts of agricultural lands, modifies agricultural lands, modifies watersheds, disrupts natural watersheds, disrupts natural habitats (including wetlands), habitats (including wetlands), and threatens the existence of and threatens the existence of wildlife species.wildlife species.

Poor land management Poor land management practices have led to practices have led to overcropping, overgrazing, and overcropping, overgrazing, and failure to use cover crops. This failure to use cover crops. This has resulted in the loss of has resulted in the loss of valuable soil nutrients and valuable soil nutrients and topsoil.topsoil.

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5. Technological Oversight5. Technological Oversight Have led to unplanned Have led to unplanned

consequences which consequences which have contributed to the have contributed to the pollution of the water, pollution of the water, air, and land.air, and land.

Examples are:Examples are:

a) Water Pollutiona) Water Pollution

b) Air Pollutionb) Air Pollution

c) Biocide Usec) Biocide Use

d) Disposal Problemsd) Disposal Problems

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Water PollutionWater Pollution

Major water Major water pollutants include: pollutants include: heat, sewage, and heat, sewage, and chemicals such as chemicals such as phosphates, heavy phosphates, heavy metals, and PCB’s.metals, and PCB’s.

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Air PollutionAir PollutionMajor air pollutants include: Major air pollutants include:

carbon monoxide, carbon monoxide, hydrocarbons, and hydrocarbons, and particulates. Nitrogen oxides particulates. Nitrogen oxides and sulfur dioxide combine and sulfur dioxide combine with water vapor creating acid with water vapor creating acid rain problems.rain problems.

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Biocide UseBiocide Use The use of some The use of some

biocides (such as biocides (such as pesticides) without a pesticides) without a complete assessment of complete assessment of their environmental their environmental impact has impact has contaminated the soil, contaminated the soil, atmosphere, water atmosphere, water supply, and has supply, and has disrupted food webs.disrupted food webs.

Ex: DDTEx: DDT

                                                

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Disposal ProblemsDisposal Problems The affluent lifestyle of The affluent lifestyle of

humans currently humans currently requires increasing requires increasing supplies of products supplies of products and energy, the and energy, the production of which production of which produces considerable produces considerable wastes: solid, chemical, wastes: solid, chemical, and nuclear.and nuclear.

       

        

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2. Positive Aspects2. Positive Aspects Through increased awareness of Through increased awareness of

ecological interactions, humans ecological interactions, humans have attempted to prevent have attempted to prevent continued disruptions of the continued disruptions of the environment and to counteract environment and to counteract the results of many of our the results of many of our negative practices.negative practices.

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Examples of Positive AspectsExamples of Positive Aspects

1.1. Population ControlPopulation Control

2.2. Conservation of ResourcesConservation of Resources

3.3. Pollution ControlPollution Control

4.4. Species PreservationSpecies Preservation

5.5. Biological ControlBiological Control

6.6. LawsLaws

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Population ControlPopulation Control

Methods of controlling the Methods of controlling the human reproductive rate human reproductive rate have been, and continue to be have been, and continue to be developed.developed.

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Conservation of ResourcesConservation of Resources Soil cover plantings Soil cover plantings

(reforestation and (reforestation and covercropping) serve covercropping) serve as erosion controls.as erosion controls.

Water and energy Water and energy conserving measures conserving measures are currently being are currently being implemented.implemented.

The economic The economic significance of significance of recycling is now being recycling is now being realized.realized.

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Pollution ControlPollution Control

Attempts are being made to Attempts are being made to control air and water control air and water pollution by laws and by the pollution by laws and by the development of new development of new techniques of sanitation.techniques of sanitation.

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Species PreservationSpecies Preservation Some efforts to sustain endangered Some efforts to sustain endangered

species have included habitat species have included habitat protection (wildlife refuges and protection (wildlife refuges and national parks) and wildlife national parks) and wildlife management (game lawa and management (game lawa and fisheries).fisheries).

Animals which were once Animals which were once endangered are now successfully endangered are now successfully reproducing and increasing their reproducing and increasing their numbers.numbers.

Examples of endangered animals Examples of endangered animals which are responding to which are responding to conservation efforts and beginning conservation efforts and beginning to make a comeback are the bald to make a comeback are the bald eagle and the peregrine falcon.eagle and the peregrine falcon.

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Biological ControlBiological Control Biological control of insect pests continues Biological control of insect pests continues

to be encouraged.to be encouraged. This method is less likely to affect those This method is less likely to affect those

species which are beneficial to humans, species which are beneficial to humans, disrupt food webs, and contaminate the disrupt food webs, and contaminate the land.land.

Examples include the use of sex hormones Examples include the use of sex hormones and natural parasites.and natural parasites.

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LawsLaws There are laws which regulate and guide There are laws which regulate and guide

the use of natural habitats.the use of natural habitats. Example: SEQR-Example: SEQR- A New York State law designed to A New York State law designed to

provide the opportunity for citizen provide the opportunity for citizen review and comment of the review and comment of the environmental impact of any proposed environmental impact of any proposed development that has been determined to development that has been determined to have significant effect on the have significant effect on the environment.environment.

EcosystemEcosystem

Functional unit of ecologyFunctional unit of ecology Contains biotic and abiotic factorsContains biotic and abiotic factors

Requirements:Requirements:

Cycling of materialCycling of material

Organisms to capture energyOrganisms to capture energy

Constant supply of energyConstant supply of energy

Interactions: Food chains and food websInteractions: Food chains and food webs

Food web better because of more biodiversityFood web better because of more biodiversity