lecture note 19 for BGYB50

School

University of Toronto Scarborough

Department

Biological Sciences

Course Code

BIOC50H3

Professor

Herbert Kronzucker

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LECTURE 19:

- Competition between cells, organisms, populations, and species can either be:

(a) direct (also known as “contest” or “interference” competition) or

(b) indirect (also known as “resource” or “scramble” competition)

- When individuals of the same species compete, we speak of intraspecific competition; if

individuals of different species compete, we call it interspecific

- Biological competition is defined by:

(a) the direct or indirect “struggle” for a limiting resource (e.g. space, food, sexual

partner),

(b) reduction of resource availability due to the activity of the competing organisms,

and

“partners” in a competition scenario are affected (a -/- interaction)

- Plants can engage in direct competition as well, e.g. through allelopathy, the production

of chemicals that inhibit the germination or growth of neighbouring plants (it is a form of

“chemical warfare”; many allelopathically active chemicals are also of medicinal value)

- Competition also plays itself out at the cellular level

- For competition to become manifest, resources (most often space, food, or mating

partners) must be limiting

- Central to the understanding of competition, as to so many other things, is the concept

of ecological optima and tolerance limits of biological organisms: Because the majority

of organisms in a population in principle “like” similar things (e.g. one type of food,

spaces with a certain temperature), organisms are forced to compete for the latter when

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Document Summary

Competition between cells, organisms, populations, and species can either be: (a) direct (also known as contest or interference competition) or (b) indirect (also known as resource or scramble competition) When individuals of the same species compete, we speak of intraspecific competition; if individuals of different species compete, we call it interspecific. Partners in a competition scenario are affected (a -/- interaction) Plants can engage in direct competition as well, e. g. through allelopathy, the production of chemicals that inhibit the germination or growth of neighbouring plants (it is a form of. Chemical warfare ; many allelopathically active chemicals are also of medicinal value) Competition also plays itself out at the cellular level. For competition to become manifest, resources (most often space, food, or mating partners) must be limiting. Ultimately, adaptive radiation into different niches is the natural consequence of ongoing pressure of competition (e. g. tree warblers, flight patterns of migratory birds,

lecture note 19 for BGYB50

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