ENVIRONMENTAL ENVIRONMENTAL SCIENCESCIENCE

Chapter 8 Understanding Chapter 8 Understanding PopulationsPopulations

8.2 How Species Interact With 8.2 How Species Interact With Each OtherEach Other

8.2 How Species Interact With 8.2 How Species Interact With Each Other ObjectivesEach Other Objectives

Explain the difference between niche Explain the difference between niche and habitat.and habitat.

Give examples of parts of a niche.Give examples of parts of a niche. Describe the five major types of Describe the five major types of

interactions between species.interactions between species. Explain the difference between Explain the difference between

parasitism and predation.parasitism and predation. Explain how symbiotic relationships Explain how symbiotic relationships

may evolve.may evolve.

IntroductionIntroduction In order to In order to

understand a understand a species, it is best species, it is best to study it in its to study it in its natural natural environment.environment.

The interactions The interactions between species between species in the natural in the natural environment are environment are often complex and often complex and cannot be cannot be replicated exactly replicated exactly in an artificial in an artificial habitat. habitat.

An Organism’s NicheAn Organism’s Niche A niche is the specific role of a species in A niche is the specific role of a species in

an ecosystem.an ecosystem. A niche can include the environmental A niche can include the environmental

factors necessary for survival of that factors necessary for survival of that species, the species’ home, and all of the species, the species’ home, and all of the species’ interactions with other organisms.species’ interactions with other organisms.

A habitat is simply a location and type of A habitat is simply a location and type of factors in that location.factors in that location.

A niche involves the habitat plus A niche involves the habitat plus interactions and behaviors characteristic interactions and behaviors characteristic of the species.of the species.

An Organism’s NicheAn Organism’s Niche A niche can also be A niche can also be

described as the described as the functional role, or functional role, or “job” of a species in “job” of a species in an ecosystem.an ecosystem.

For example, the bison For example, the bison is the large grazer on is the large grazer on the plains of North the plains of North America and the America and the kangaroo is the large kangaroo is the large grazer in the grazer in the grasslands of grasslands of Australia.Australia.

Ways in Which Species InteractWays in Which Species Interact

There are five major types of species There are five major types of species interactions.interactions.• Competition – each species negatively affects Competition – each species negatively affects

the otherthe other• Predation – one species consumes the other Predation – one species consumes the other

speciesspecies• Parasitism – a smaller species feeds off of the Parasitism – a smaller species feeds off of the

tissues or fluids of another speciestissues or fluids of another species• Mutualism – each species is helpful to the otherMutualism – each species is helpful to the other• Commensalism – one species benefits from the Commensalism – one species benefits from the

relationship, but the other is unaffectedrelationship, but the other is unaffected

Ways in Which Species InteractWays in Which Species Interact The categories of species interaction are The categories of species interaction are

based on whether harm or benefit is based on whether harm or benefit is caused by the interaction.caused by the interaction.

Other types of interactions between Other types of interactions between species are possible.species are possible.

Some types of interactions between Some types of interactions between individuals are atypical and do not individuals are atypical and do not represent the general trend as related to represent the general trend as related to the species involved.the species involved.

Many interactions in nature are still not Many interactions in nature are still not well studied.well studied.

CompetitionCompetition Competition is part of daily life for most Competition is part of daily life for most

species from male lions competing for who species from male lions competing for who will dominate the pride to kudzu will dominate the pride to kudzu competing for sunlight as it overgrows a competing for sunlight as it overgrows a stand of trees in an interstate median.stand of trees in an interstate median.

Competition is a relationship in which Competition is a relationship in which individuals or populations attempt to use individuals or populations attempt to use the same limited resource.the same limited resource.

Each individual, as a result of the Each individual, as a result of the competition, has less access to the competition, has less access to the resource and is therefore harmed by the resource and is therefore harmed by the competition.competition.

CompetitionCompetition Competition can occur between individuals of a Competition can occur between individuals of a

species or between species themselves.species or between species themselves. Members of the same species tend to occupy the Members of the same species tend to occupy the

same niche, therefore, they will compete among same niche, therefore, they will compete among themselves.themselves.

If the niches of two different species overlap, then If the niches of two different species overlap, then they will compete for the resources.they will compete for the resources.

Indirect competition is when species compete Indirect competition is when species compete with one another for resources, yet they never with one another for resources, yet they never come in direct contact while using the resources.come in direct contact while using the resources.

For example, humans compete with insects for For example, humans compete with insects for the crops that we grow for food.the crops that we grow for food.

CompetitionCompetition When two species with overlapping or similar When two species with overlapping or similar

niches are placed in the same ecosystem, the niches are placed in the same ecosystem, the compete directly against one anther.compete directly against one anther.

Sometimes one species out-competes the other Sometimes one species out-competes the other and pushes it out of the habitat through and pushes it out of the habitat through competitive exclusion.competitive exclusion.

If the change is slow enough, one species may be If the change is slow enough, one species may be able to adapt and change enough so that both able to adapt and change enough so that both species remain extant.species remain extant.

Niche restriction occurs when each species uses Niche restriction occurs when each species uses less of the niche than they are capable of using.less of the niche than they are capable of using.

Niche restriction often occurs between two Niche restriction often occurs between two closely related species using the same resources closely related species using the same resources in a habitat. in a habitat.

PredationPredation An organism that kills and consumes An organism that kills and consumes

another organism is called a predator.another organism is called a predator. The organism that is fed upon is called the The organism that is fed upon is called the

prey.prey. Predation is the relationship where a Predation is the relationship where a

predator kills and consumes the prey.predator kills and consumes the prey. A snake eating a mouse is an example of A snake eating a mouse is an example of

predation.predation. In complex food webs – typical of most In complex food webs – typical of most

ecosystems – predators can be the prey in ecosystems – predators can be the prey in some cases.some cases.

PredationPredation Most organisms have evolved some sort of Most organisms have evolved some sort of

defense against predation like the toxic taste of defense against predation like the toxic taste of some toads or the shell of a tortoise.some toads or the shell of a tortoise.

Predator populations tend to mirror prey Predator populations tend to mirror prey populations in an ecosystem with a short lag populations in an ecosystem with a short lag time.time.

For example, if a prey population spikes, the For example, if a prey population spikes, the predator population will spike shortly thereafter predator population will spike shortly thereafter due to the abundant food sorce.due to the abundant food sorce.

When the predator population has increased, a When the predator population has increased, a decrease will be noticed in the prey population decrease will be noticed in the prey population due to increased predation.due to increased predation.

ParasitismParasitism An organism that lives in or on another An organism that lives in or on another

organism and feeds off of its tissues or organism and feeds off of its tissues or fluids is called a parasite.fluids is called a parasite.

Parasitism is rarely fatal.Parasitism is rarely fatal. The parasite takes nourishment from the The parasite takes nourishment from the

host organism.host organism. Parasites are normally much smaller than Parasites are normally much smaller than

their host.their host. Examples of parasites include ticks, fleas, Examples of parasites include ticks, fleas,

hookworms, tapeworms, leeches, and hookworms, tapeworms, leeches, and mistletoe.mistletoe.

MutualismMutualism A close relationship between two species A close relationship between two species

in which both species benefit is called in which both species benefit is called mutualism.mutualism.

Humans and intestinal bacteria are an Humans and intestinal bacteria are an example of mutualism because the example of mutualism because the bacteria help us with the breakdown of bacteria help us with the breakdown of food and the synthesis of certain vitamins food and the synthesis of certain vitamins and our intestine provides habitat and and our intestine provides habitat and food for these bacteria.food for these bacteria.

Termites and the intestinal protozoa are Termites and the intestinal protozoa are another example because termites alone another example because termites alone cannot digest wood!cannot digest wood!

CommensalismCommensalism

Commensalism occurs when a relationship Commensalism occurs when a relationship exists in which one species benefits and exists in which one species benefits and the other species is neither harmed nor the other species is neither harmed nor helped.helped.

Remoras, which hitch a ride with a shark Remoras, which hitch a ride with a shark to get scraps of food, and sharks are an to get scraps of food, and sharks are an example of comensalism.example of comensalism.

Birds used trees for habitat and neither Birds used trees for habitat and neither harm, nor help the tree.harm, nor help the tree.

Symbiosis and CoevolutionSymbiosis and Coevolution

Symbiosis is any relationship in which two Symbiosis is any relationship in which two organisms live in close association.organisms live in close association.

Many interactions are considered Many interactions are considered symbiotic in some way.symbiotic in some way.

Over time, species involved in close Over time, species involved in close relationships may coevolve.relationships may coevolve.

Coevolution occurs when the evolutionary Coevolution occurs when the evolutionary pathway of a species is affected by pathway of a species is affected by another species.another species.

Symbiosis and CoevolutionSymbiosis and Coevolution

Flowering plants and Flowering plants and their insect pollinators their insect pollinators often exhibit extreme often exhibit extreme cases of coevolution.cases of coevolution.

The development of The development of articulation in articulation in brachiopods to starfish brachiopods to starfish predation is another predation is another example of example of coevolution.coevolution.

ReferencesReferences Arctic Food Web - Arctic Food Web -

http://bioinquiry.biol.vt.edu/bioinquiry/Cheetah/chhttp://bioinquiry.biol.vt.edu/bioinquiry/Cheetah/cheetahpaid/cheetahhtmls/ecosysfdweb1.htmleetahpaid/cheetahhtmls/ecosysfdweb1.html

Bison - Bison - http://www.americaslibrary.gov/es/sd/es_sd_bisonhttp://www.americaslibrary.gov/es/sd/es_sd_bison_1_e.html_1_e.html

Kangaroo - Kangaroo - http://faculty.uca.edu/~johnc/comparative_anatohttp://faculty.uca.edu/~johnc/comparative_anatomy_vertebrat1441.htmmy_vertebrat1441.htm

Hippo and Tortoise - Hippo and Tortoise - http://bigpicture.typepad.com/writing/2005/02/hiphttp://bigpicture.typepad.com/writing/2005/02/hippo_adopts_10.htmlpo_adopts_10.html

ReferencesReferences Mammal That Ate a Dinosaur - Mammal That Ate a Dinosaur -

http://www.msnbc.msn.com/id/6817636?Ghttp://www.msnbc.msn.com/id/6817636?GT1=6065T1=6065

Barnacles and Niche - Barnacles and Niche - http://io.uwinnipeg.ca/~simmons/ysesp/cohttp://io.uwinnipeg.ca/~simmons/ysesp/comeco8.htmmeco8.htm

Predator and Prey Populations - Predator and Prey Populations - http://www.tvdsb.on.ca/saunders/courses/http://www.tvdsb.on.ca/saunders/courses/online/SBI3C/Environmental_Science/populonline/SBI3C/Environmental_Science/population_curves.htmation_curves.htm

Flea (parasite) - Flea (parasite) - http://www.naturespet.com/flea.html http://www.naturespet.com/flea.html

ReferencesReferences Flea (musician) - Flea (musician) - http://http://

www.guitarcenter.com/interview/flea/indexwww.guitarcenter.com/interview/flea/index.cfm.cfm

Mistletoe - Mistletoe - http://http://www.hsu.edu/content.aspx?idwww.hsu.edu/content.aspx?id=1878=1878

Tapeworm - Tapeworm - http://www.riverside.sd43.bc.ca/art/long_bihttp://www.riverside.sd43.bc.ca/art/long_bi_11/cestoda/pages/Tapeworm_jpeg.htm_11/cestoda/pages/Tapeworm_jpeg.htm

Trichonympha - Trichonympha - http://biology.unm.edu/ccouncil/Biology_2http://biology.unm.edu/ccouncil/Biology_203/Summaries/Protists.htm03/Summaries/Protists.htm

ReferencesReferences

Termite Intestines Spilled - Termite Intestines Spilled - http://http://www.stcsc.edu/ecology/TermSymb.htmwww.stcsc.edu/ecology/TermSymb.htm

Termites - Termites - http://http://www.thesahara.net/termites.htmwww.thesahara.net/termites.htm

Remoras With Whale Shark - Remoras With Whale Shark - http://flmnh.ufl.edu/fish/Gallery/Descript/Whttp://flmnh.ufl.edu/fish/Gallery/Descript/Whaleshark/whaleshark.htmlhaleshark/whaleshark.html

Remora - http://foros.pesca.org.mx/cgi-Remora - http://foros.pesca.org.mx/cgi-bin/Blah.pl?b=IGFA,m=1111122886 bin/Blah.pl?b=IGFA,m=1111122886

ReferencesReferences

Barnacles on a Whale - Barnacles on a Whale - http://www.coreresearch.org/what.hthttp://www.coreresearch.org/what.htm m

Insect Pollination - Insect Pollination - http://faculty.uca.edu/~johnc/represehttp://faculty.uca.edu/~johnc/representative_plant_groups.htm ntative_plant_groups.htm