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Download Keystone Species How do prey avoid predators? Spatial refugia
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Keystone Species Paine (1966): keystone predation • Single species role critical to community • Keystone species effect is disproportionate to its’ abundance • Pisaster removal results in mussels dominating and excluding competitors for space • The presence of the predator removes the competitive edge thereby increasing species diversity of invertebrates and algae How do prey avoid predators? • • • • • Spatial refugia Use of space (spatial refugia) Grow large (size refugia) High growth rates Toxicity Cryptic Spatial refugia 1 Size refugia Biotic interactions (symbiosis) • Commensalism- • Mutualism- also animal pollinators, seed dispersers Mychorrizae: mutualistic relationship between plants and fungi • arbuscular (AMF)- fungus within the root cortex cells • ectomychorrizae (ECM)- fungus forms mantle around root cells 15_03.jpg Food Webs Secondary Carnivore (tertiary consumer) Carnivore (secondary consumer) Herbivores (primary consumer) Sunlight & Nutrients Plant (producers) 2 Food web organization of pitcher plant inquiline community Wyeomyia smithii Protozoans Rotifers Food web descriptions • • • • Connectedness Energy flow Functional webs Food chain length Bacteria Mites Prey (Dead Insects) Food Webs Food Webs Secondary Carnivore (tertiary consumer) Secondary Carnivore (tertiary consumer) Carnivore (secondary consumer) Carnivore (secondary consumer) Herbivores (primary consumer) Plant (producers) Omnivore Herbivores (primary consumer) Plant (producers) 3 Trophic cascade Trophic cascade Predator (+) Herbivore (+) Herbivore (-) Plant (-) Plant (+) Trophic cascade Mosquito larvae (+) Rotifers (-) Bacteria Abundance Bacteria Bacteria Richness (+) Kneitel and Miller (2002) Ecology 4
