wk 9 Lec 1sf

wk 9 Lec 1sf - Chapters18&19...

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Ecology, Communities and Ecosystems
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An overview of ecology Ecology The scientific study of the  interactions between organisms and  their environments . The environment can be divided  into two major components. Abiotic Consists of nonliving chemical and  physical factors. Biotic   Includes the living factors.
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Hierarchy of interactions Ecology can be divided into four increasingly comprehensive levels: Organismal ecology : concerned with evolutionary adaptations that enable  individual organisms to meet the challenges posed by their abiotic environments. Population ecology : concerned with populations, groups of individuals of the  same species living in the same area and concentrates mainly on factors that  affect population density and growth. Community ecology : concerned with communities, assemblages of populations of  different species. Also focuses on how interactions between species affect  community structure and organization. Ecosystem ecology : concerned with ecosystems, which include all the abiotic  factors in addition to the community of species in a certain area. Also focuses on  energy flow and the cycling of chemicals among the various abiotic and biotic  factors.
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Key Properties of Communities A community is an  assemblage of species living  close enough together for  potential interaction. The  diversity  of a community  is the  variety  of different  kinds of organisms that make  up the community.
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Key Properties of Communities:   Diversity The diversity of a  community has  two  components : Species richness , the total  number of different species  in the community Relative abundance  of the  different species
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Key Properties of Communities:   Prevalent form of vegetation The prevalent form of vegetation  mainly depends on the terrestrial  situation. The types and structural  features of plants in a  community largely determine the  kinds of animals that live in the  community.
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Key Properties of Communities:   Stability and Trophic Structure Community stability  refers to the community’s  ability to resist change and return to its  original species combination after being  disturbed. Stability depends on both the type of  community and the nature of disturbances. The  trophic structure  of a community concerns  the feeding relationships among the various  species making up the community.
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Interspecific Interactions in Communities Interspecific interactions are  interactions  between species . Interspecific competition may occur when two 
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This note was uploaded on 09/23/2011 for the course BIO 141 taught by Professor Brown during the Fall '08 term at Drexel.

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wk 9 Lec 1sf - Chapters18&19...

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