Lecture 24: Olfactory Signaling: Production and Transmission

Sound Features

Directionality: Relatively straight

Speed: medium

Temporal Pattern: retained

Spectrum: yes, use fourier analysis

Persistence: short

Honest Signaling: can be good

Light Features

Directionality: relatively straight

Speed: fast

Temporal Pattern: retained

Spectrum: yes use fourier analysis

Persistence: does not persist at all

Honest signaling: can be good

Olfactory features

Directionality: Very irregular path

Speed: slow

Temporal Pattern: lost a short distance away from the source

Spectrum: no, must analyze a different way

Persistence: can be long, provides a clock

Honest signaling: good, often a direct measure of the internal state of the animal, difficult to blush

Chemical Signaling uses

• bacteria (single cell organisms)

• transfer of molecules from sender to receiver

Why are olfactory signals difficult to fake?

They often provide a direct chemical indication of an animal’s internal state.

What are hormones?

A chemical signal used for communication between organs within the same body.

What is a pheromone?

A chemical signal used for communication between individuals of the same species.

What is an allomone?

A chemical signal used for communication between different species.

Example of an allomone?

Lycaenid caterpillars release chemicals to attract ants that protect them from predators.

What role do pheromones play in pigs?

Male pigs produce sex pheromones that stimulate ovulation in females.

Example of hormones

hypothalamus controls pituitary glad and gonadotropins to control sex hormones

Pheroboar

boar substitute spray to get female excited and induce ovulation in female pig

How are pheromones chemically idenitified?

gas chromatography

What characteristic must airborne pheromones have?

They must be light molecules to travel long distances

Example of airborne pheromone?

Bombykol produced by female silk moths

How do we know which compounds are important?

• bio assays

• ask animal itself

• sex and alarm pheromones give a big response

What is electroantennograms?

• measure antennal response

• asking antenna of animal what chemical is important to you

What are mediums of phermones

1. air borne

2. water borne

3. contact

Air born pheromone features

• must be light

• ex is silk moth

Water borne pheromone features

• should be water soluble

• can be heavy

Example of water borne pheromone

splendiferin

• aquatic pheromone of tree frog

Contact pheromone features

• many possibilities

• can be heavy

• can stay wherever for a long time

• don’t travel

What glands commonly produce pheromones in mammals?

• exocrine glands (contact)

• sebaceous (oil) and sudoriferous (sweat) glands

Which gland produces pheromones in hedgehogs during courtship?

salivary gland

How can the excretory system produce pheromones?

through urine and feces

ex is red back salamander female to detect male from feces to tell if male is in a good territory or bad one

Example of spraying in insects

ants spraying formic acid as an alarm pheromone\

What is rubbing in pheromone release?

Depositing scent by rubbing body parts on surfaces

• ex cat scratching bark

• mongoose rubbing anal gland on trees

• hartebeests rub oil

Example of multimodal communication

• skunk

  • black and white is warning coloration

  • stomping to look bigger

  • visual, acoustic, and chemical communication

  • spray is a chemical

What is fanning in pheromone release?

Using wing or body movement to disperse pheromones

• ex: bat: males give off pheromone and wafts scent to female

  • stimulates female to bind to male socially

What is diffusion?

molecules moving down a concentration gradient (takes a while for odor to transfer around room)

What is active space?

• region in which a receiver can detect a pheromone signal

• initially expands and then shrinks as the pheromone dissipates

Q/K ratio gives

size of active space

Q=

number of molecules emitted

K=

response threshold

Sex Pheromone Q/K

10^10 to 10^12

Alarm Pheromone Q/K

10³ to 10^5

Trail Pheromone Q/K

1

Ant Trail Active Space

odor droplets form a cloud

What is laminar flow

transmit odor in a straight line

What is turbulent flow?

reduced active space, odor scatters in all different directions