Batesian Mimicry - Classification and Comparisons

Classification and Comparisons

Batesian mimicry is a case of protective or defensive mimicry, where the mimic does best by avoiding confrontations with the signal receiver. It is a disjunct system, which means that all three parties are from a different species. Batesian mimicry stands in contrast to other forms such as aggressive mimicry, where the mimic profits from interactions with the signal receiver. One such case of this is in fireflies, where females of one species mimic the mating signals of another species, deceiving males to come close enough for them to eat. Mimicry need not involve a predator at all though. Such is the case in dispersal mimicry, where the mimic once again benefits from the encounter. For instance, some fungi have their spores dispersed by insects by smelling like carrion. In protective mimicry, the meeting between mimic and dupe is not such a fortuitous occasion for the mimic, and the signals it mimics tend to lower the probability of such an encounter.

One case somewhat similar to Batesian mimicry is that of mimetic weeds, which imitate agricultural crops. Once again, this is the result of the signal receiver's action, not a cunning ploy of the mimic. In weed, or Vavilovian mimicry, the weed does not profit from encounters with man or his winnowing machinery; at best the weed is left, at worst it is destroyed. Vavilovian mimicry is not a case of Batesian mimicry, however, because man and crop are not enemies. Indeed, the crops derive their protection from insects, weeds, and competition with other plants from their growers.

Another analogous case within a single species has been termed Browerian mimicry (after Lincoln P. Brower and Jane Van Zandt Brower). This is a case of bipolar (only two species involved) automimicry; the model is same species as its mimic. Equivalent to Batesian mimicry within a single species, it occurs when there is a palatability spectrum within a population of harmful prey. For example, Monarch Butterflies (Danaus plexippus) feed on milkweed species of varying toxicity. Some larvae will feed on more toxic plants, and store these toxins within themselves, while others will not. The less palatable caterpillars will thus profit from those that ingest high levels of toxic substances, just as other butterfly species benefit from mimicry of Monarchs.