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Lecture 16

Lecture 16 Ecological Consequences of Genetic Variation
Lecture 16 Ecological Consequences of Genetic Variation

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School
University of Toronto St. George
Department
Biology
Course
BIO220H1
Professor
Doug Thomson
Semester
Winter

Description
Lecture 16 BIO220 Ecological Consequences of Genetic Variation Biodiversity  resistance to perturbation, increased productivity e.g. High species richness, high biomass after drought Are plant patches that are more genetically diverse able to support more insects? • Grow groups of monocultures (only 1 genotype), or polycultures (mixture) • Measure # and identify herbivores, omnivores, predators Result: more genetically diverse plant communities support more predatory insects. Increased number of genotypes, predator richness Mechanism: • Genotypes in mixture react additively o Genotypes independent o Predator abundance on a genotype in monoculture = abundance on that genotype in polyculture o Communities: whole is sum of parts • Genotypes in mixture react non-additively o Properties of genotype depend on other surrounding genotypes o Abundance of predators on genotype in monoculture do not predict that in polyculture o Communities: whole is > or < than sum of parts Whole > sum of parts • Plant genotypes differ in nutritional qualities, growth, defensive compounds, flowering phonologies • More diverse patches, more spatial, temporal niches for insects • Once insects find a patch, they may be more likely to stay and visit other nearby genotypes Polycultures recover from severe disturbances faster, are more resilient to natural disturbance Mechanism: • Polycultures: more tolerant genotypes, can regrow quickly • Overperformance of polycultures: interaction between genotypes o Different resource uptake strategies of genotypes o More micro-niches, less competition Galled plants decompose slower, have greater retention of C/N compared to ungalled. Genetic variation affects nutrition cycling • Chain of causation o Genotypes differ in chemical properties o Different attack by insects o Genotypes differ in chemical responses to attack o Combined set of chemical differences alter decomposition, nutrition cycling Coyote Bush • Facilitates colonization of other species • 2 distinct genotypes: affect light, temperature, litter depth, which affect biomass, % cover, species richness of colonizers o erect • Tall, more light, low litter depth, hotter • More biomass, % cover, species richness o Prostrate • Short, Low light, High litter depth, Low Temperature Genotypes differ in architecture  alt
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