Lecture11_CommunitiesA

Lecture11_CommunitiesA - Last Time: Last Time: Population...

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Last Time: Population Ecology - How do we measure populations -- the 4 Ds - Models of population growth Exponential : birth and death rate are constant over time Logistic : growth rate is density-dependent - Factors regulating population growth 2,000 1,500 1,000 500 0 0 5 10 15 Number of generations Population size ( N ) Exponential growth Logistic growth 1 Thursday, November 5, 2009 Last Time: Exponential & logistic models of population growth N t+1 = N t + B - D + I - E N t+1 = N t (b - d) per capita births/deaths N t+1 = N t r r = per capita rate of increase (growth rate) N/ t = N r any time interval dN/dt = N r instantaneous population growth rate r = instantaneous per capita growth rate Population size Immigration (+) Emigration (-) Deaths (-) Births (+) 2 Thursday, November 5, 2009 How do populations interact? Objectives 1. Describe the primary types of interspeci±c interactions, and give examples of each 2. Understand the outcomes of competitive interactions 3. Predict the outcome of disturbance on species interactions 3 Thursday, November 5, 2009 What is a community? An assemblage of interacting species - Two or more populations interacting Is the de±nition of a community ±xed? 4 Thursday, November 5, 2009
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Mountain Yellow-Legged Frogs With a neighbor: Compare the models you drew of the MYLF system. Combine to form a single food web 5 Thursday, November 5, 2009 Mountain Yellow-Legged Frogs Autotroph (Primary Producer) Herbivore (Primary Consumer) Carnivore (Secondary Consumer) Tertiary Consumer Adult MYLF MYLF Tadpole Algae Terrestrial & Aquatic Insects Native Predators (ie. garter snakes) Introduced Trout Fungal Pathogen (Bd) + + + + + + + - - - - - - - - - - - 6 Thursday, November 5, 2009 Mountain Yellow-Legged Frogs Adult MYLF MYLF Tadpole Algae Terrestrial & Aquatic Insects Native Predators (ie. garter snakes) Introduced Trout Fungal Pathogen (Bd) + + + + + + + - - - - - - - - - - - 7 Thursday, November 5, 2009 Mountain Yellow-Legged Frogs Sierra garter snakes are specialist predators of both adult and tadpole MYLF. What do you think will happen to populations of these garter snakes in lakes where trout have been introduced?
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This note was uploaded on 12/02/2009 for the course BILD BILD 3 taught by Professor Woodruff during the Fall '08 term at UCSD.

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Lecture11_CommunitiesA - Last Time: Last Time: Population...

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