Hello Carlos

I just want to start saying that evolution occurs through selection (or other forces like random drift) and that selection is performed by some agent (predator, competitor,ecosystem....), thus it is the agent the one that selects. I'd say that is incorrect to say that evolution selects.

Selection would affect the sender and/or the receiver depending on the fitness gain. I don't know with what organism you are working but if we were talking of males trying to attract females though singing, fitness will be higher when a mate is effectively engaged. You'll have fitness differences among males depending on the "singing quality" (defined as the effectiveness to attract mates). The sender is therefore selected.

I cannot really thing of natural examples where effectively receiving calls or messages increase fitness but if receiving a message gives an advantage over other individuals, these receivers would be selected and have greater fitness.

Hi Daniel,

Sorry for the lack of formalism. I have edited my original question, and I hope it sounds better now. Thanks for pointing that out. Either way, I guess the question could be better put. Could a communication process be selected upon a fitness gain restricted to senders (or to receivers)? You see, why does an individual sends a message if not for fitness gain? Similarly, why would a receiver alter its behaviour in a response to a call if not for a fitness gain? It seems to me a communication process can only be established if there are gains for both. Is there any discussion on the subject?

Best.

The Evolution of Animal Communication by William A. Searcy & Stephen Nowicki is a great book that provides a discussion of fitness benefits from a sender and receiver perspective in a variety of signaling contexts. Looks like the first chapter is available free online if you search for it on Google. I took an entire class just on the book though, and it was a great read!

It is not necessary that sender and receiver both benefit from a new communication process. Many signals arise by 'exploiting' the sensory system of the receiver. For example, guppy males attract more attention by females when their color matches that of the most preferred food of the females. This way, males can evolve a certain color that later plays an important role in sexual selection. The color trait (it depends on your definition from which point onward you call it a 'signal') may spread even if mating with colored males would be disadvantageous for females. A recent review article on this 'sensory exploitation hypothesis' is Ter Hofstede et al. (2015) in Current Biology.

Many thanks for the literature indication! Brent and Franz! Best. 

Please excuse me for being even more formal, as I am not at ease with some points of preceding responses. As a behaviorist, I will not use sentences as “males trying to attract females” and “effectively engaged”.

First, natural - and sexual – selections do not act on individuals but on heritable traits in populations of individuals. So it is the trait - not the individual - which is selected, or rather, which has been selected, and not that “will” be selected as formulated too often. Therefore your question is about selection of receivers’ traits and on emitters’ traits, if you agree.

The signal bears characteristics from the emitter‘s DNA in the structure of the emitter organ, and from the receiver’s DNA in that of the receiver’s organ. If the trait favors the emitter’s survival and reproduction or that of its kin, it will be favored. Same if it favors the receiver’s. Franz points that the emitter’s signal trait may be disadvantageous for the receiver (looking like food as a male trait), but in that case, such receivers will be disadvantaged in the situation. Therefore why the trait - that makes such loser females respond - did not disappear from the population (as such DNA carriers survive or reproduce less): because the trait surely shows very advantageous for other functions (finding food).

Let me give you an example of mine that may further respond your question. “Schreckstoff” is a mix of molecules that a fish such as a minnow emits when caught by a predator such as a pike; Schreckstoff is efficient in chasing away other minnows, even when emitter is dead. How can you explain it? Well if other minnows (potential prey) around are kin, they are likely to share the trait (ability to chase other “schoolmates” away) and inclusive fitness favors the emitter’s trait to be maintained in the population. But even if prey and potential prey are not related (and even of different species), the Schreckstoff remains an efficient signal because other receivers possess receptor system traits that make them react to the Schreckstoff. Thus the receivers’ signal traits have been selected, because they have saved their bearers. This may be easier to understand by comparison to human aversive reaction to the sight or smell of corpses or feces: receiver’s signal traits have been selected as they have prevented their carriers from various dangers, such as diseases.

Hope this helps

Christian

Sorry, but I must disagree. Selection acts on phenotypes (a set of traits), not on a single trait. For sure selection will favour traits that provide the highest fitness, but as fitness may be defied as the number of descendants an INDIVIDUAL leaves, it is an individual parameter, not a trait one. From Behaviour Ecology (Krebs and Davies) "We can think of ecology as setting the stage on which animals must perform their behaviour, and evolution as a process which selects individuals whose behaviour results in greatest success in the struggle to contribute genes to the population's gene pool."

Now, coming back to our discussion on evolution within communication systems, communication may be defined as the way one mind affects another (Weaver 1949) and so there are two minds involved. Thus, the comparison to the aversive reaction to the sight or smell of corpses is not proper, as without the intent it is a clue, it is not a communication signal. 

Carlos, I have been working with fish vocalizations lately and I actually do think that metadata about some animals can be contained in their vocalization process. if a few pubs get approved, I'll send you a link, but I think for example that fish are capable of modulating their inherent (e.g. pattern generated via brain wiring) communication signal with body parts. think of it as an analogy to two men, one how has started puberty and one who has finished puberty trying to woo a girl. the girl can hear the completed change in the man who has finished puberty - no voice cracking, lower frequencies with better control of said frequencies. this is lacking in the pre-pubescent male. is that what you're asking after? at some point physics takes over and the body loses sight of the genetic elements driving it. I am sure its traceable though.

Carlos,

Check out aggressive mimicry for examples of deception.

Thanks a lot for the recent comments! Best