1. Chemical Signals Types Production Transmission Reception

2. Olfactory signal features Directionality –Generally propagate away, but rarely linear Transmission speed –Depends on diffusion rates, wind speeds Temporal pattern –Difficult to turn on and off Spectrum –Multi-dimensional

3. Chemical signals Hormone –Chemical signals used within individuals –Produced by endocrine glands Pheromone –Chemical signals used between conspecifics –Produced by exocrine glands Allomone –Chemical signals used between species

4. Pheromone examples Diffusion rate is inversely related to molecule size. Small compounds are volatile. Large compounds can persist

5. Odor glands in mammal skin

6. Vertebrate glands

7. Scent dissemination strategies

8. Female marking by greater spear- nosed bats

9. Multi-modal signalling in sac- winged bats

10. Scent glands in ants

11. Diffusion of a scent puff K = threshold of detection, r A = active space, t = time

12. Active space is dynamic There is a maximum size of active space which is set by the detection threshold and amount of odorant released

13. Media affects transmission Q = number of molecules released K = detection threshold D = diffusion rate

14. Diffusion from a trail Treat as if there are a series of single emissions from a moving source

15. Diffusion in laminar flow

16. Diffusion in turbulent flow

17. Moth active space in wind

18. Insect odor receptor organs

19. Insect olfactory sensilla

20. Vertebrate odor receptor organs Vomeronasal organ detects steroid hormones in urine

21. Olfactory receptor cell Olfactory receptor proteins have 7 trans-membrane domains, but belong to a gene family with over 1000 loci. Receptor cells Are short-lived (< 60 d), and express a single protein. creates odor-topic map in olfactory bulb

22. Gradient detection and orientation Simultaneous sampling –Requires paired olfactory receptors at sides of body. –Need wide head or nose on appendage (antenna) Sequential sampling –Animals follow concentration gradient, requires tracking back and forth across trail.

23. Moth scent tracking Animals follow concentration gradient, requires tracking back and forth across trail. Some have paired olfactory receptors at sides of body.