Adaptive Value

Why are you copying me? Please, stop.

Tinbergen's final question address the adaptive value of a particular trait, or, why is this behavior important and how has it given the species an a survival advantage in it's environment? Quite obviously, looking like a poisonous animal is going to increase your own chances of survival, hence the selective pressures on some organisms to evolve copycat schemes.

In what ways are these adaptations valuable?

This question can be divided according to the type of mimicry in question, Batsean or Müllerian. Each hypothesis proposes a different survival strategy and adaptive value.

Batesian Mimicry

It has been suggested that Batsean mimicry is a form of parasitism of the copycat organism on the truly inedible model organism. The idea underlying this proposal is this: of two similar species, Species X is palatable while Species Y is poisonous. This encourages, through selective pressure on patterning, chemical cues, etc., for Species X to imitate its bad-tasting neighbor. Now there are two similar-looking species – one of which is poisonous and one of which is tasty. Since the effectiveness of this strategy is primarily based on predators learning to associate the smoke with the fire, the full effectiveness of the signal never takes full effect – despite the signaling the predator will catch from these indistinguishable species edible prey theoretically as often as an inedible prey. Thus Species Y, the honest signaler, is taken advantage of survival-wise. Its signal is not effective and it incurs a higher mortality cost than it would if Species X did not look the same. [8]

coral snakes as batesian mimicsBatesan mimicry the venomous coral snake and the non-venomous king snake. The similar patterning would make it very hard for a predator to distinugush between the snakes, especially from a great distance, like as an eagle flying overhead would experience.
<http://www.mun.ca/biology/scarr/Coral_snake_mimics.gif>

 

Mullerian Mimicry

While Batsean mimicry is a form of parasitism, Müllerian mimicry is much more of a mutual relationship. Many different species, all honest signalers, have adapted very similar patterning, so that they all are relatively indistinguishable to predators. This form of mimicry is also centered on the idea predator learning. If all of these species are inedible, and all of them look the same, the theory is that all of the species involved will equally share the mortality cost of predators learning to associate the honest signals with the unpleasant experience of eating those species. This is a case of unintentional mutualism, since none of these species actively choose to share the same signals. Selection has driven the adaptation of the shared patterning because no one species is different enough to be singled out by predators an therefore take an unequally heavy hit by predators. [8]