Blog Post 2 - Defensive Mimicry Pt 1

Batesian Mimicry


Survival in nature is largely a matter of eating and trying not to be eaten by predators and rivals. Many animals work an “honest” living through their size, strength and hunting methods, however there are numerous animals who have chosen to weave deception, treachery, and downright fraud into their lives. 

As introduced in my post last week, these animals do this through mimicry. For the next 2 weeks I will be focusing on a defensive form – Batesian mimicry – while trying to understand the genetics and evolution of this mimicry. We can recall from my last post that defensive mimicry is basically where animals with several predators resemble other dangerous animals for protection. We can also recall that Batesian mimicry is where a harmless organism mimics the aposematic traits of a harmful organism to be avoided by predators. 
 


Mimicry has always been considered as strong evidence for natural selection with predation as the driving force (Ceccarelli and Crozier, 2006). Multiple studies have presented population genetics models to explain Batesian mimicry and what these models have generally found is that polymorphism can be maintained in mimic populations (Ceccarelli and Crozier, 2006). These studies have also found that rates of evolution can be effected by relative population sizes of the model and the mimic, the closeness of the mimics resemblance to the model or predator learning (Ceccearelli and Crozier, 2006). 
 


However, one traditional idea involving the evolution of Batesian Mimicry is the two-step hypothesis. According to this model, a major mutation of large effect first produces a rough resemblance to the model, enough for predators to generalize their avoidance of the model to the new mimic, followed by fine tuning of the mimic’s appearance toward the model (Kazemi et al. 2017). This fine tuning can improve the mimicry through fixation of “modifier” alleles and these modifiers affect specific morphs such as colour changes closer of that to the model (Brooker et al. 2015). This two-step mechanism is the reigning paradigm for explaining the evolution of Batesian mimicry (Kikuchi and Pfenning, 2010). 
 
Join me next week as I attempt to explore the evolution of Batesian Mimicry through an animal example.  
Check out this video of a deep sea trickster - the mimic octopus (Thaumoctopus mimicus). The ability of this harmless species to mimic both the colours and shapes of numerous harmful species is an incredible display of Batesian Mimicry. 




Reference List:


Booker, T., Ness, R.W. and Charlesworth, D., 2015. Molecular evolution: breakthroughs and mysteries in Batesian mimicry. Current Biology, 25(12), pp.R506-R508.


Ceccarelli, F.S. and Crozier, R.H., 2007. Dynamics of the evolution of Batesian mimicry: molecular phylogenetic analysis of ant‐mimicking Myrmarachne (Araneae: Salticidae) species and their ant models. Journal of Evolutionary Biology, 20(1), pp.286-295.


Kazemi, B., Gamberale‐Stille, G., Wåtz, T., Wiklund, C. and Leimar, O., 2018. Learning of salient prey traits explains Batesian mimicry evolution. Evolution, 72(3), pp.531-539.

Kikuchi, D.W. and Pfennig, D.W., 2009. High-model abundance may permit the gradual evolution of Batesian mimicry: an experimental test. Proceedings of the Royal Society B: Biological Sciences, 277(1684), pp.1041-1048.  
 

Comments

  1. Tasmin26 March 2019 at 20:58

    Very interesting! I’m wondering though what the trigger of this mutation (that leads to morphological variation) could be?

    ReplyDelete

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