Stealth crickets

[Skye]

Faced with parasitic flies that are attracted to the calls, silent variants of black field crickets in Hawaii have been reported to have emerged and become quite successful. This has apparently occurred over about 5 years, pretty quick to me, but then I'm not a cricket. The problem for the stealth crickets is that now the female crickets can't hear them. So the stealth crickets huddle about the remaining chirpy crickets and steal their mates. Cricket ingenuity seems to know no bounds.

 

I think it will be interesting to see how the proportion of chirpy and stealth cricket in the population changes over time.

 

http://sciencenow.sciencemag.org/cgi/content/full/2006/921/2

[Edtharan]

o the stealth crickets huddle about the remaining chirpy crickets and steal their mates. Cricket ingenuity seems to know no bounds.

There was most likely this kind of behaviour in the crickets already. There is usually a fair bit of variation in the mateing strategies, even within a species.

 

You probably would have found that a few crickets would attempt to steal another's mate (weather they sang or not). This behaviour would have been present, but normally it would not have been very successful.

 

With the introduction of a prasitic fly that could use the sound of the crickets to locate a potential victem, this would have completely flipped the selection criteria.

 

Now, crickets that sung would be killed off quickly by the introduced fly. This would mean that only a small numebr of them would survive to sing, when compared to those that tried to steel a mate.

 

The crickets that tried to steal their mates would be in a greater proportion to the singer than they were before. This would increase their chances of stealing a mate as well has having the benifit of not being as detectable to the fly.

 

There is, however, a limit for this. If no crickets sung then none of them will be able to find a mate. So the remnant of the "singers" will persist in the population.

 

It is my oppinion that over the next few years the population might experience a crash. This would be because not enough of the singers will exist (due to predation by the parasitic fly) and therefore the number of females encountered for mating will decline.

 

this will in turn increase the rate of singers that get to mate, strengthining their genes in the gene pool of the crickets. If there are enough crickets (both singers and non singers) that survive and the poredation by the fly is not too extreme, then you will get a fluctuation of boom/bust cycles in the population and it will eventually settle down to a stable state (not constant, but astable cycle of boom/bust).

 

If the predation rate of the fyl is too great, you will find that the population of crickets will crash and they will either remain very low or die off entierly. If the fly has other sources for their parasitic behaviours (like another host species that it can use) then the second scenario is more likely. If the fly does not have another host that it can use, then the first scenario becomes the most likely.

 

There are many of the factors that will make this hard to predict (like birth rates, other predators of both the fly and the crickets, life cycle times, etc).

 

I would say that over a few thousand generations (100 years or so), if the crickets survive, we will see marked changes in their populations that will make then as a seperate or sub species (especially if there is a constant source of reintroduction of the original species some how). Eventually it will become its own species of cricket.

 

For thouse that deny the existance of a transitional form, then this cricket looks to be a good conterporary for one. It has developed traits that will eventually (if these conditions hold) force a change that will make interbreeding between it and the original group unfavourable (different genes for the smooth wing phenotype frequency and other behaviours and mutations), creating a new species.