Week 10- Ecology (Population and Community)
Week 10- Ecology (Population and Community) Biology 152
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This 3 page Class Notes was uploaded by BettyAnn Mead on Friday April 10, 2015. The Class Notes belongs to Biology 152 at University of Massachusetts taught by Peteh in Winter2015. Since its upload, it has received 81 views.
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Date Created: 04/10/15
What is Ecology o Ernst Hackel 1866 From Greek term for home quotOikosquot quotThe total relations between an organism and is organic and inorganic environment Molles quotThe study of the relationships between organisms and the environmentquot Townsend Harper Begon 2000 quotThe scienti c study of the distribution and abundance of organisms and the interactions that determine distribution and abundance o HOULIHAN Today quotThe scienti c study of the patterns of distribution and abundance of organisms and the mechanisms that determine the patterns of distribution and abundance Ecology Patterns Distribution and abundance Mechanisms Interactions between organisms and their environments 0 Both nonliving abiotic and living biotic components of the environment 0 Focus Distinguished by the level of organization at which ecologists work Levels of Organization 0 Organism An individual animal 0 Population Groups of individuals of same species inhabiting an area 0 Community Groups of populations in an area Ecosystem Communities and nonliving components 0 Biosphere The entire earth system Why study population ecology o The environment of an organism consists of anything that might effect it s chance to survive and reproduce When we model the ecology of an organism we only include those components of the environment that matter What are the components of and organism s environment 0 Abiotic Nonliving nutrients climate etc o Biotic Living Population Dynamics The patterns of and mechanisms of population change Population Growth and Regulation Simple model of population growth 0 Change in population size Births Deaths IGNORING EMMIGRATION AND IMMIGRATION rgt0 population is growing rlt0 population is shrinking r0 population is stable Exponential Growth dNdtrN If r remains constant and gt0 the number of individuals added to the population each year grows continuously Curve has no upper limit Population size increases more rapidly when r is larger A population has a hypothetical maximum possible value of r The intrinsic rate of increase rmax Represents a populations growth rate under ideal conditions unlimited resources In the real world populations do not maintain exponential growth 0 Population growth approaches a limit 0 r declines o Eventually a limit is reached 0 r0 0 Population has reached it s maximum sustainable size carrying capacity 0 Designated K Populations size increases inde nitely at a rate determined by the rate of increase Logistic Growth Population size increases at an increasing rate and then at a diminishing rate until it reaches a limit called carrying capacity K dNdtrmaxNK NK What limits population growth 0 Density dependent factors 0 Predation Including parasitism 0 Availability of resources Example Food space etc o Accumulation of wastes 0 Behavior change 0 Density independent factors 0 Weather Example Annual freezes periodic droughts oods unpredictable storms etc 0 Sex ratio 0 Age structure 0 Community Ecology Characteristics of community as a whole Interactions among species Competition 0 Use or defense of a resource by one individual that reduces the availability of that resource to other individuals 0 Can be intraspeci c within a species or interspeci c between species 0 ntraspeci c competition is most intense members of same species consume the same resources Resource Any substance or factor that is used by an organism 0 And that can lead to increased population growth as its availability increases Example Food water space hiding places etc 0 Population size is limited by quantity and quality of resources especially the limiting resources Limiting Resources The resources that are scarce relative to the demand for them
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