Communication … What is it??
Everybody: Think of a definition
Bare Minimum for Communication
SENDER produces
a stimulus
e.g. movement
odor
sound
display
etc.
RECEIVER sensory
neurons detect the stimulus
e.g. vision
olfaction
audition
etc.
Receiver brain
interprets signal
PNS
CNS
SIGNALS
What are they?
Senders send them ……………… Receivers receive them
Properties of Signal Categories
PROPERTY
VISUAL AUDITORY CHEMICAL TACTILE
Distance
medium long
long
Localization
high
Around Obstacles?
Poor
good
good
good
Exchange Rate
fast
fast
slow
fast
Complexity
high
high
low
medium
Duration (time)
variable low
high
low
medium variable
short
high
CHEMICAL COMMUNICATION
Evolutionary oldest … most primitive form of communication?
Prokaryotes to Primates !!!!!
Advantages
* Transmits around obstacles and at night
* May be long-lasting (transmits into the future)
* Effective over long distances
* Private message …. Eavesdropping requires specific olfactory receptors
Disadvantages
* Slow
* Not directional (wind dependent)
What is a Pheromone??
Chemical(s) released by an individual that communicates
information to a conspecific.
Pheromones can be classified as
i) "releasers" - affect another animal's behaviors
e.g., alarm pheromones, mating attractants
ii) "primers" - affect another animal's physiology
e.g., Bruce Effect: odor of new male’s urine induces
abortion.
Urination scent marking by wolf packs: territory delineation
Today: Be thinking of ways to investigate chemical communication in termites
Terrestrial Pheromones
Volatile chemical released by an animal
that communicates information to
another individual of the same species.
Volatility??
Molecular wt. < ~ 500
High vapor pressure
Pheromones in aquatic animals??
Components of Trail Pheromones of Ants
(found in venom reservoirs)
Components of Trail Pheromones of Ants
(found in Dufour glands and hindgut)
Components of Trail Pheromones of Ants
(from the following glands: pygidial, Pavan, post-pygidial, & tibial)
Female gypsy moth
emits mating
pheromone
How does the male
locate her?
Natural selection may ……
•adjust a pheromone’s volatility
• adjust emission rate
• change receiver’s olfactory sensitivity
Active Space is the volume of air in
which the pheromone is effective
Active Space is environmentally dependent
Active Space is also physiologically influenced by Q/K
Q = emission rate
K = threshold concentration at which a response occurs
(K > the receiver’s olfactory threshold)
Q/K ??
Q/K ??
TRAIL PHEROMONES IN ANTS & TERMITES
Phylum Arthropoda
Class Insecta
Order Hymenoptera
Order Isoptera
Eusocial insects: bees, wasps, ants, termites
Termite Castes
Soldier
Worker
Queen
Food Source
If a worker finds food, it deposits trail
pheromone while returning to the nest
worker
pheromone
trail
Trail Following
Behavior in Termites
Pheromone
Concentration
edge middle edge
Plume Width
Nest
Path Corrections
In
Trail Following
1
1 = control ant
2 = left antenna amputated
3 = antennae glued crossed
2
3
Termite Videos
Lab Ideas
Trail-following Accuracy
~ Σ Squares
http://www.scielo.br/img/revistas/ne/v38n1/01t2.gif
TAXES
Nonrandom movements toward or away from a stimulus.
Animals will orient long axis in line with the stimulus & move.
Why long axis???
(+) taxis
(-) taxis
Taxes are named according to the environmental
stimulus being used for orientation:
geotaxis - gravity (earthworm)
rheotaxis - water current (trout)
phototaxis - light (bats in a cave)
chemotaxis - chemical (male moths following
female pheromones)