Nov 03 2009

Nov 03 2009 - BIEB 132 Species Interactions II 1)...

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Unformatted text preview: BIEB 132 Species Interactions II 1) predation- benefits one species, negative effects on second species 2) competition- negative effects on both species 3) mutualism- positive effects on both species Symbiosis - living in close association with another species 1) mutualism - host benefits (+, +) 2) commensalism - host not affected (0, +) Symbiont benefits in both cases Common on coral reefs - partly responsible for high diversity Zonation common on coral reefs (as in rocky intertidal)- physical tolerances and species interactions important Endosymbionts: species living inside of another organism in a mutualistic relationship (benefits both host and endosymbiont) Zooxanthellae endosymbionts of corals and other invertebrates- dinoflagellates ( Symbiodinium ) Zooxanthellae: photosynthetic, converting light energy into carbohydrates, some of which are used by host coral Coral: provides habitat for zooxanthellae, nutrients, etc Mutualistic symbiosis, benefiting both interacting species (+, +) Zooxanthellae of Corals Diversity was at one time thought to be relatively low: one or at most a few species in many species of corals Evidence: similar morphology of endosymbionts Recent genetic research has shown there to be multiple forms of zooxanthellae- across species of corals- within a single species of coral- within a single coral colony Habitat partitioning (zonation) of zooxanthellae occurs Different forms occur in high light areas and low light areas of coral (top versus sides; shallow versus deep) Genotype diversity of zooxanthellae (from Rowan et al., 1997) Under stress, corals bleach by losing their zooxanthellae Stress: sedimentation (coastal development) Stress: warm water (global warming) Stress: elevated carbohydrates Corals will die if they are without zooxanthellae for long Lineages of zooxanthellae differ in their susceptibility Some hope for corals surviving global warming Diversity of zooxanthellae (from Knowlton & Rowan, 2003) Zooxanthellae are found in other invertebrates Giant Tridacna clams, upside-down jellies Living with Invertebrates:...
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This note was uploaded on 02/23/2010 for the course BIEB BIEB 132 taught by Professor Hastings during the Fall '09 term at UCSD.

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Nov 03 2009 - BIEB 132 Species Interactions II 1)...

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