Eco%205_Interspecific%20Relations

Eco%205_Interspecific%20Relations - Interspecific...

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Unformatted text preview: Interspecific interactions Ecology, Lecture 5: Interspecific Relationships Competition, predation/herbivory, commensalism, mutualism Classification of interspecific relationships Competition, the niche, character displacement Modeling competition (the Lotka-Volterra equations) Predation, predator avoidance, predator-prey cycles Herbivory and defense against herbivory Mutualism and commensalism The categories are defined by the effect of the interaction on the participating species (+ or –) 1 2 Types of competition Competitive Exclusion Principle Interference Competition G. F. Gause (1910-1986) 3 4 Types of competition Exploitative Competition 5 6 Realized niche Niche: fundamental and realized Realized niches High Tide Chthamalus Balanus Low Tide 7 8 Modeling Interspecific Competition Fundamental niche The Lotka-Volterra equations High Tide Fundamental niche dN1 = r1 N1 dt K1 – N1 – α N2 K1 dN2 = r2 N2 dt Chthamalus K2 – N2 – β N1 K2 The competition coefficient α = proportional effect of species 2 on species 1 β = proportional effect of species 1 on species 2 Low Tide 9 10 Community structure in Anolis lizards Character displacement in Geospiza finches Beak depth Resource Partitioning Percentages of individuals in each size class G. fuliginosa A. ricordii A. insolitus “Ghost of competition past” A. aliniger A. distichus A. christophei A. cybotes Los Hermanos 40 G. fuliginosa, allopatric 20 0 60 Daphne 40 G. fortis, allopatric 20 0 60 Santa María, San Cristóbal Sympatric populations 40 20 0 8 A. etheridgei G. fortis 60 10 12 14 16 Beak depth (mm) 11 12 Predation The “true predators” have many hosts, and the relationship is always lethal 13 14 Predator Defense Aposematism Poison dart frog 15 16 Predator Defense Crypticity and Camouflage Canyon tree frog 17 18 Predator Defense Müllerian mimicry Cuckoo bee Yellow jacket 19 20 Predator Defense Batesian mimicry Isle Royale, Lake Superior Green parrot snake Hawkmoth larva 21 22 Wolves and moose of Isle Royale Wolves Moose 2,000 30 1,500 20 1,000 10 500 0 1955 # of moose 2,500 40 # of wolves 50 0 1965 1975 1985 1995 2005 Year 23 24 120 Lynx 9 80 6 40 3 0 1850 1900 1875 1925 # of lynx (thousands) # of hares (thousands) Snowshoe hare 160 0 Year 25 26 Types of herbivory Herbivory 27 28 Parasites & Parasitoids Parasites have one or a few hosts and are rarely lethal 29 30 Mutualism Parasitoids have one host and are always lethal Pollination 31 32 We can distinguish between obligate and facultative mutualisms Cultivation of livestock Ants and aphids 33 Cultivation of crops 34 Gut “flora” Ants and fungi 35 36 Lichen Coral Fungi and algae (or cyanobacteria) Coral polyp and zooxanthellae 37 Commensalism 39 38 ...
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This note was uploaded on 09/16/2010 for the course BIO 1B taught by Professor Carlson,mischel,power during the Fall '07 term at University of California, Berkeley.

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