Lecture 18 - BIO220

Ksrutorontoca 7 8 johnson et al 2005 ecol lett 9 24

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Unformatted text preview: opportunities, go to: www.ksr.utoronto.ca 7 8 Johnson et al. 2005, Ecol. Lett. 9: 24 34 -More plant genotypes leads to more predators coming to these patches depending on the species diversity of plants -These predators are not actually eating the plants themselves -Predators are eating what ELSE comes to the plant (like spiders that hunt the plants) -What is going on here cannot be a function of predators actually eating different genotypes differentially -These predators are NOT herbivores What is the mechanism? • Genotypes in mixture react additively • Genotypes in mixture interact non additively Additivity: Non additive: Genotypes are independent Properties of a genotype depend on surrounding genotypes Predator abundance on a genotype in monoculture = abundance on that genotype in polyculture Abundance of predators on a genotype in monoculture do not predict abundances in polycultures Communities: the whole is the sum of the parts Total Arthropods Communities: the whole is either greater or less than the sum of the parts Predators Omnivores 9 -Non-Additive: Genotype A will only support more predators when it is grown w. Genotype B -Property depends on who its neighbours are - A very branchy plant gives a lot of hiding spots for predators. A plant near by that is resistant to predation: branchy genotype will not have preds in this case -The dynamic of this interaction is not intrinsic to the genotype, it is the dynamic i nteraction Johnson et al. 2005, Ecol. Lett. 9: 24 34 10 -Omnivores and Predators have greater abundances than would be dictated by the expected results -The expected results were estimated off of monoculture data (then multiplied by 4 for example for 4 g enotypes grown together) -There are more omni and pred in diverse communities wikipedia Why is the whole > sum...
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