Course investigates the ecology of the unseen chemistry underlying species interactions. Students do not need to be chemists, only to have a curiosity about how nature works. We will cover diverse topics using Darwinian natural selection as a framework: e.g., communication, defenses, pheromones, toxins, mutualism, deception, mimicry, social interactions.
Athena Title
Chemical Ecology
Prerequisite
(BIOL 1107 or BIOL 1107E or BIOL 2107H) and (BIOL 1108 or BIOL 2108H)
Semester Course Offered
Offered spring
Grading System
A - F (Traditional)
Student learning Outcomes
Students will be able to understand experimental design and the scientific method as it applies to species interactions.
Students will be able to categorize ecological interactions and potential mechanism by which they are mediated.
Students will be able to discuss these mechanisms in the context of evolutionary theory and draw conclusions about potential applications to agriculture and health.
Students will be familiar with a number of analytical, behavioral, and experimental techniques used to analyze chemical compounds that mediate ecological interactions.
Students will be familiar with the general chemical structures of organic molecules and their relationship to function.
Students will be able to read and synthesize findings from original scientific research in chemical ecology by studying and discussing the literature.
Topical Outline
1. Course Introduction, What is chemical ecology and how can we use it to learn about interactions between insects, plants, and microbes?
2. A chemical ecology case study: Chilies, capsaicin, seed dispersal, and human use
• Plant interactions with animals and microbes
• Directed Deterrence Hypothesis
3. A ecological primer on species interactions and the roles chemicals play
• Chemical signals: Hormones, pheromones, allelochemicals (allomone, kairomone, synomone)
• Types of ecological interactions
• Competitive exclusion principle
4. An evolutionary primer on species interactions and the roles chemicals play
• Coevolution: phenotype matching and allele matching
• Mimicry: Batesian and Mullerian
5. Ecological chemistry and biological activity, Pheromones
• Classes of organic compounds and functional groups
• How chemical structure and ecological context determine mode of action
• Biosynthetic pathways and secondary metabolism
• Types of pheromones: sex, trail, aggregation, alarm
• Pheromone actions: primers and releasers
• Pheromone detection: receptors, coding and signal perception
6. Methods in Chemical Ecology
• Chemical analytical techniques to identify natural products: Extraction, volatile headspace, chromatography, Fractionation
• Experimental assays to measure biological activity: Bioassay design and controls, attraction assays of scale and choice, relative response assays, induction assays
7. Lab demonstration of Gas Chromotography – Mass Spectrometry
8. Pollinator networks and floral markets
• Pollination strategies: hypergeneralist, specialist guild, obligate mutualist, deception
• Chemical floral rewards - Nectar sugars, amino acids, and salts; Pollen starches, lipids, and proteins, floral oils
• Floral strategies for increasing gene flow and dispersal
• Floral advertisement
• Insect learned preference
9. Toxic nectar
• Food webs
• Costs and Benefits of specialization vs generalization pollination
• Nicotine case study: alter pollinator behavior, repel herbivores
10. Pollination by sexual deception
• Behavioral differences in insect sex and the impact on floral outcrossing
• Ecological context of insect pheromones and floral mimics
• Orchid bee pheromone collection from flowers
11. Nursery pollination and obligate mutualism
• How does obligate mutualism evolove
• Conflicts of interest between plants and pollinators that feed on floral parts
• Obligate pollination in dioecious plants
• Mechanisms of stabilizing mutualisms (partner choice and sanctions)
• Cheaters and parasites
12. Chemistry of fruit dispersal
• Directed dispersal through fruit chemistry
• Chemistry of dispersal dynamics
• Chemistry of ant seed dispersal
13. Discussion 1 – Pollination syndromes
14. Project 1: ‘Design a Flower’ breakout group work
15. Animal defense and toxicity
• Sequestration
• Convergent evolution
16. Tri-tropic interactions
• Ecological niche
• Chemical mediated interactions: functional redundance, multi-functionality, synergistic functionality, specificity, signal cross-talk, complexity, context-dependent
• Plant tannins context dependent impact on herbivory
17. Plant defense and herbivore counter-defense
• Mechanisms of plant resistance (deterrence, toxicity, reduce digestibility) and herbivore counter-defense
• Herbivore physiology of plant defense traits
• Herbivore counter-defense
18. Discussion 2 ¬– Plant-plant communication
19. Community ecology of plant defense, why are there so many secondary compounds
• Plant hormonal response to herbivory and pathogens
• Direct defense and indirect defense
• Cross talk between plant hormonal pathways and the impact on plant visitors (herbivores and pollinators)
• Hypothesis for multiple secondary compounds: specificity, synergism, environmental impact of effectiveness
• Population variation in defense
20. Induced defenses
• Induced responses, induced resistance and induced defenses
• Induced resistance vs constitutive resistance
• Transgenerational induced resistance
21. Social insect chemical communication
• Genetic relatedness of social insects
• Chemistry of altruistic behavior in genetically related insects
• Ant trail pheromones
• Bumblebee volatile signaling for food availability
• Honeybee odor communication
22. Host-microbe and microbe-microbe interactions
• Chemical communication of microbes: quorum sensing, siderophores, biofluorescence
• Microbial cooperation: biofilms
• Multi-cellular microbial behaviors: nutrient acquisition, competition
• Symbiosis: mutualistic, communalistic, parasitic; obligate, facultative
• Vertical and horizontal transmission
23. Lab demonstration 2: Bioassay techniques and olfactometers
24. Peer review of perspectives paper in small groups
25. Pheromones revisited: mating disruption and pest management
• Methods of trap development
• Pheromone traps for monitoring pests
• Push-pull strategies for pest control
26. Bioprospecting; Chemical ecology of insect vectored diseases
• Natural products
• Mosquito attraction
27. Discussion 3 – Push-pull agriculture in Africa
28. Invasive Pest Project breakout group work
29. Human Chemical Ecology
• Animal pheromones to reduce inbreeding
• Human pheromones
30. Present final project
