Introduction to Batesian Mimicry

Prey species use a huge variety of defense mechanisms to avoid being eaten; some species spray formic acid, some species confuse their attacker by suddenly jumping into the air, and some species simply run away as fast as they can. Other species leave a bad taste, or sometimes make their attacker ill, when eaten. Whilst this usually doesn't help the individual being eaten (rest in many pieces, little guy), predators learn to avoid that particular species - resulting in protection for a whole population of that prey species. 

Often, prey will announce how dangerous or bad-tasting they are by having distinct markings, or colours. Enter center stage, the Batesian Mimic (who, spoiler alert, lies). Batesian mimicry is a type of defensive mimicry which involves a non-harmful species looking like a harmful species (called a 'model') to avoid being eaten (Allen and Cooper, 1995).

Figure 1: Mimetic Scarlet King Snake and its model, the Eastern Coral Snake

Logic dictates that Batesian mimicry would be frequency-dependant (ie: the number of mimetic individuals would be limited by the number of model individuals), and this has been shown to be the case is the majority of mimetic species such as the Scarlet King Snake shown in Figure 1, where the frequency of predation on the mimic species decreased with increased relative abundance of the model species (Pfennig et al., 2001). 

This is not always the case, however, as hoverflies are more abundant than their wasp model species (Dittrich et al., 1993). In cases such as this, the model species is usually so dangerous that it is thought that predators will avoid any prey which looks like the model, even if the chance of catching a harmless mimic is much higher than catching the actual dangerous species; "better safe than sorry" springs to mind.

Interestingly, it has been suggested that mimicking a species that can easily escape a predator can be just as an effective method to avoid predation as mimicking a harmful species. It is suspected that a certain predator could associate markings/colours of a very agile prey species as being a "waste of energy" and will not try to catch said species. As such, a less agile species (that would otherwise be easy to catch and eat) could mimic the "waste of energy" model and hence, predators would not bother trying to eat it (Gibson, 1974).

- Allen, J. A. and Cooper, J. M. 1995, ‘Mimicry’, Journal of Biological Education, vol. 29, no. 1, pp. 23-26
- Dittrich, W., Gilbert, F., Green, P., McGregor, P. and Grewcock, D. 1993, 'Imperfect mimicry: a pigeon's perspective', Proceedings of the Royal Society of London, vol. 251, no. 1332, pp. 195-200.
- Gibson, D. O. 1974, 'Batesian mimicry without distastefulness?', Nature, vol. 250, no. 1, pp. 77-79.
- Pfennig, D. W., Harcombe, W. R. and Pfennig, K. S. 2001, 'Frequency-dependent Batesian mimicry', Nature, vol. 410, no. 1, pp. 323.

- Figure 1: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitNsKjhlsSlWcgdJytSdJiVK6ez4yB3Z_-aMSUENLRV6ONjT-eIP-dGLRN6qe3bKocz3bxaYlrgl4hQSWz7I_pO0cDIDlkYUoBUN6M5VHiLNuTK4570r5BIWzKZR9Cv_ud-qmpkvwv5xGq/s1600/Coral_snake_mimics.gif