chapter53[1]competition mine

8/14/2019 Chapter53[1]Competition MINE

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COMPETITION

K GOPI


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Introduction

Community

comprises all the populations of organisms

inhabiting a common environment andinteracting with one another

These interactions are competitive, predatory, or

symbiotic.


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CompetitionIntroduction

Competition interaction between

individual organisms

of the same species(intraspecific) or of adifferent species(interspecific)usingthe same resource,

often in limitedsupply

e.g. food, water, light,living space

http://www.chagres.com/AE-3.html
http://www.chagres.com/AE-3.htmlhttp://www.chagres.com/AE-3.html


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CompetitionIntroduction

Interferencecompetition Involves overt fighting

or other face-to-faceinteraction

Exploitativecompetition

Involves removal of aresource, leaving lessfor others

http://www.deer.rr.ualberta.ca/library/guild/functional_interactions.htm
http://www.deer.rr.ualberta.ca/library/guild/functional_interactions.htmhttp://www.deer.rr.ualberta.ca/library/guild/functional_interactions.htm


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CompetitionThe Principles of Competitive Exclusion

G. F. Gause formulated principle of

competitive exclusion.

If two species are in competition for the samelimited resource, one or the other will be more

efficient at utilizing or controlling access to this

resource and will eventually eliminate the other

in situations in which they occur together.


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CompetitionThe Principles of Competitive Exclusion

In Gauses experiment,Paramecium aureliaoutmultiplied

Paramecium caudatum.

http://www.personal.dundee.ac.uk/~amjones/dundee/34ecologyintro.htm
http://www.personal.dundee.ac.uk/~amjones/dundee/34ecologyintro.htmhttp://www.personal.dundee.ac.uk/~amjones/dundee/34ecologyintro.htm


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CompetitionResource Partitioning

Resources arefrequently

partitioned among

ecologically similarmembers of acommunity.

http://www.personal.dundee.ac.uk/~amjones/dundee/34ecologyintro.htm
http://www.personal.dundee.ac.uk/~amjones/dundee/34ecologyintro.htmhttp://www.personal.dundee.ac.uk/~amjones/dundee/34ecologyintro.htm


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Woodland Warblers Robert MacArthur

observed and timedwhere warblers fedwithin trees. His data

showed that the fivespecies studied each havedifferent feeding zones inthe trees. Because theyexploit slightly differentresources, the species cancoexist.

http://mil.citrus.cc.ca.us/cat2courses/bio104/ChapterNotes/Chapter43notesLewis.htm
http://mil.citrus.cc.ca.us/cat2courses/bio104/ChapterNotes/Chapter43notesLewis.htmhttp://mil.citrus.cc.ca.us/cat2courses/bio104/ChapterNotes/Chapter43notesLewis.htm


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Bog Mosses In bogs, mosses of

the genus Sphagnumoften appear to forma continuous cover,and several speciesare involved.Although all thespecies ofSphagnum

coexist, they actuallyoccupy differentmicrohabitats.

http://botit.botany.wisc.edu/images/veg/N.Wet_N.Wet_Mesic/Bunchberry+sphagnum_moss_VK.html
http://botit.botany.wisc.edu/images/veg/N.Wet_N.Wet_Mesic/Bunchberry+sphagnum_moss_VK.htmlhttp://botit.botany.wisc.edu/images/veg/N.Wet_N.Wet_Mesic/Bunchberry+sphagnum_moss_VK.html


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African Ungulates Similarly, leaf and grass

eaters of East Africapartition their resources.

Browsers (leaf eaters)

consume leaves atdifferent heights.

e.g giraffes vs.rhinos

Grazers (grass eaters)

consume different typesof grass.

e.g. zebra vs.gazelle

http://www.wildlife-pictures-online.com/giraffepictures2.html
http://www.wildlife-pictures-online.com/giraffepictures2.htmlhttp://www.wildlife-pictures-online.com/giraffepictures2.html


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The Role of Past Competition in Resource Partitioning

http://www.cuencanet.com/ortiz/galfinches.htm
http://www.cuencanet.com/ortiz/galfinches.htmhttp://www.cuencanet.com/ortiz/galfinches.htmhttp://www.cuencanet.com/ortiz/galfinches.htm


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CompetitionExperimental Approaches to the Study of Competition

Barnacles in Scotland

One of the clearest demonstrations of

competition in a natural community was a

study of two species of barnacles,Chthamalus stellatus andSemibalanus

balanoides, performed by Joseph Connell.


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Patterns on the Rocky Shore

The position of plants and animals along theintertidal zone is far from random - there are distinct

patterns in the distribution of certain species.

The causes of these zonation patterns have beenthoroughly investigated and were previouslythought to be the result of the organisms' ability tosurvive the changes in tide level and extendedperiods out of water.

The distribution of species is governed not only byphysical factors, such as the length of time speciesare left out of water, but also by biological factors, orthe interactions between other species on the shore.


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Out of Water

The hardiest organisms, able to survive longer periods exposed to theair, tend to be found higher up the shore in the drier areas. Thus therocky shore community is divided into distinct bands characterised

by certain species.

Right at the top, just below the land plants, there is a 'splash' zone ofblack, yellow and grey lichens. These plants are rarely covered bythe tides, but are frequently splashed with salt water by waves.

Below the lichens there is usually a greyish or white band ofbarnacles, and these may extend down over most of the mid-shore.

On rocky or stony shorelines, various types of tough brownseaweeds, called wracks, grow alongside the barnacles, and maylargely replace the barnacles on very sheltered rocky shores.


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Chthamalus is found on the high part of theintertidal seashore, and Semibalanus occurs lowerdown, where the conditions are more suitable. When Semibalanus is removed, Chthamalus invades the

lower area and thrives there.

In the control areas, Semibalanus, which grows faster,ousts Chthamalus by crowding it off the rocks or

growing over it, keeping each in their usual zones. Tolerance limits, however, keep Semibalanus from

moving upward ifChthamals is removed.


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Tolerance hypothesis

The earliest species neither facilitate nor inhibitcolonization by later species. The species dominant

at any given time are those that can best tolerate theexisting physical conditions and availability ofresources.

Inhibition hypothesis

The early species preventrather than assistcolonization by other species.


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http://www.biol.andrews.edu/fb/spring/ch53/lect53.html
http://www.biol.andrews.edu/fb/spring/ch53/lect53.htmlhttp://www.biol.andrews.edu/fb/spring/ch53/lect53.html


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Barnacles in Scotland Fundamental niche

Physiological limits of tolerance of anorganism

Niche occupied by an organism in theabsence of interaction with otherorganisms.

Realized niche

Portion of fundamental niche actually

utilized Determined by physical factors and

also by interactions with otherorganisms

http://astro.temple.edu/~sanders1/FWlect_1_ecol.htm
http://astro.temple.edu/~sanders1/FWlect_1_ecol.htmhttp://astro.temple.edu/~sanders1/FWlect_1_ecol.htm


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PredationPredation and Species Diversity

Although predation may occasionally

eliminate a prey species, many experimental

studies have shown that it is often animportant factor in maintaining species

diversity in a community.

e.g. R. T. Painestarfish and prey

e.g. Jane Lubchencomarine snailLittorina

littorea and algae


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SymbiosisIntroduction

Parasitism One species benefits

and the other is harmed

Mutualism Both species benefit

Commensalism One species benefits

and the other isunaffected

http://www.geo.arizona.edu/Antevs/nats104/00lect20.html

http://biology.clc.uc.edu/courses/bio303/interspecific.htmhttp://www.visindavefur.hi.is/svar.asp?id=2116
http://www.geo.arizona.edu/Antevs/nats104/00lect20.htmlhttp://biology.clc.uc.edu/courses/bio303/interspecific.htmhttp://www.visindavefur.hi.is/svar.asp?id=2116http://www.visindavefur.hi.is/svar.asp?id=2116http://www.visindavefur.hi.is/svar.asp?id=2116http://www.visindavefur.hi.is/svar.asp?id=2116http://biology.clc.uc.edu/courses/bio303/interspecific.htmhttp://www.geo.arizona.edu/Antevs/nats104/00lect20.html


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SymbiosisParasitism

Parasitic diseases are most likely to wipe out thevery young, the very old, and the disabledeitherdirectly, or more often, indirectly, by making them

more susceptible to other predators or to theeffects of climate or food shortages.

A parasite-caused disease should not be toovirulent nor too efficient.

If a parasite were to kill all the hosts for which it isadapted, it too would perish.


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SymbiosisMutualism

Ants and Aracias

On one of the African species ofAracia, the ants of the genusCrematogastergnaw entrance holesin the walls of the thorns and live

permanently inside them. The antsobtain food from nectar-secretingglands on the leaves and eatcaterpillars and other herbivoresthat they find on the trees.

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