Communication and Signals II

Question 1

What is a common interest signal? What are two examples?

Answer 1

1. A signal where there is no conflict of interest between sender and receiver.

2a. Forager honey bees (direction/distance/quality of flower beds they find) (all bees are related)

2b. Bacteria quorum sensing (sensing # cells around)

Question 2

What are public goods benefits?

Answer 2

Effects where the entire population benefits

Question 2

In the quorum sensing example, what are the four reasons that exoproducts are produced? What is quorum sensing? What is an example of an autoinducer system? What are two qualities of the autoinducer compounds?

Answer 2

1. Digest prey, produce toxins to kill competitors, movement (protein surfactants), and virulence factors (overcome host immune system)
2. Each cell releases an autoinducer saying “I’m here” and is detected. After reaching a threshold, the public good benefit begins.
3. Gram +/-
4. 1) encode species identity 2) task specific

Question 3

What is a specific example of quorum sensing? What is its signal/what does it do?

Answer 3

1. Pseudomonas aeruginosa (biofilm-producing bacteria that is opportunistically pathogenic)
2. Siderophore/ converts mineral iron => metabolizable form

Question 4

How was cheating tested in the quorum sensing model? What were the two cheats? What were the results? What question resulted and what is its answer?

Answer 4

1. Diggle and colleagues made two kinds of cheaters
2. 1) signal negative strain (does not make quorum sensing protein) 2) signal blind strain (does not make exoproduct)
3. Found that cheats can invade cooperators under certain circumstances.
4. How can coops evolve if cheats can invade?
5. Evolution is change in allele frequencies, and changes in relatedness can influence how individuals behave.

Question 5

How does relatedness relate to cheating? Is relatedness required for common interest signals? What is an example?

Answer 5

1. Increase relatedness = decrease cheating (was tested in two colonies to be true)
2. No.
3. Drosophila subobscura - already mated females cannot multiply mate, and she will tell another male this (advantageous to both)

Question 6

What is an example of a common interest signal that is subtle? What is the function of the MHC? Why are MHC profiles important?

Answer 6

1. Pheromones (major histocompatibility complex MHC)
2. Bind to antigens and display them on cell surface so T-cells recognize them (humans have 200 MHC genes)
3. The more similar = children will have a worse off immune system (yay).

Question 7

What is the way that MHC profiling is thought to be communicated? What are two examples?

Answer 7

1. Cryptic female choice (females control male success from inseminating their ova AFTER mating) and
2. CFC - some insects control which sperm inseminate. Horses it was found that relatedness to male didn’t matter in any genes but MHC AND that increased fertilization rate happened with NO shared MHC genes.

Question 8

What are three quick examples of dishonest signals? Is this communication? What are the two reasons why or why not?

Answer 8

1. Anglerfish used lure
2. freshwater mussels and lure
3. caterpillars mimic bird poop

This is not communication because they are just pretending to be something else, not conveying any information. Also, it only works because the original communication system is in place (such as king snake and coral snake).

Question 9

Refresher, what is Batesian mimicry and one example? Under what condition does Batesian work? What two factors influence this condition and what is an example for each?

Answer 9

1. Harmless mimics bad (king snake/coral snake)
2. Model must be common!

1) Learning of the receiver (Heliconius butterfly predators learn whereas coral snake birds just know innate)

2) Relative cost to Receiver of mistaking the model for the mimic (coral snake is deadly on the first encounter)

Note: tiger beetle signal falls apart if you increase the number of crickets, so model must be in plenty and mimics relatively in few

Question 10

Why are alarm calls beneficial? What is an example of a deceptive alarm call? Elaborate. Why is this stable?

Answer 10

1. Predator detection, increased foraging
2. Fork-tailed drongos - will follow coop groups of pied babblers, meerkats, and glossy starlings. Sometimes give a false alarm call of a predator to steal food. They have two deceptive calls.

1) False alarm call (their own) and 2) false mimic starling call (meerkats abandon food at same rate regardless of the type of call they hear)

3. This is stable because the drongos do not exhibit these calls all the time. Instead, they only do it about 10% of the time to keep the meerkats from believing the alarm call is false.