Blog Post 4 - Defensive Mimicry Pt 2 Mullerian Mimicry 


Welcome back! This week I will be sticking with defensive forms of mimicry, but I will be moving on to explore Mullerian mimicry examples, genetics and evolution. As I briefly mentioned in my introductory post Mullerian mimicry is where multiple harmful species mimic similar appearances/converge on the same warning characteristics, for shared mutual benefits (Merrill and Jiggins, 2009). The Mullerian mimicry theory suggests that the less abundant species is generally the one to evolve to mimic a more abundant or better defended model species (Merrill and Jiggins, 2009), and this is termed as “advergence”. It is also to recognize that Mullerian mimicry frequently involves larger collections of similar-looking species, these are known as “mimicry rings” (Sherratt, 2008).


Just like I discussed in Batesian mimicry, Mullerian mimics show localized polymorphism and usually evolve by means of a major mutation whose effects are later modified (Turner, 1987). Sexual selection, selection imposed by predation, and anti-apostatic selection also play a role in the evolution of Mullerian mimic species (Sherratt, 2008). Unlike in that of a Batesian mimic, “Supergenes” are not as common in Mullerian mimics. On a genomic level, what is seen to drive this type of mimicry evolution is the invasion of dominant modifiers (dominant alleles i.e. DD/Dd vs. dd), altering gene expression through different molecular mechanisms, however, the molecular mechanisms underlying this evolution are largely unknown (Llaurens et al. 2015). Dominance plays an important role in shaping the conditions of polymorphism persistence and the frequency of alleles at a particular locus (Llaurens et al. 2015).   

Mullerian mimicry is a good example of positive selection acting at a local scale (Llaurens et al. 2015), whereby process by which new advantageous genetic variants (such as specific warning colours) sweep a population, producing mimicry rings over a gradual time frame (Motyka et al. 2018).   

Here is a cool example of Mullerian mimicry in Dendrobates frogs in Peru: 

(a - c) These three frogs are all putative members of a single species, Dendrobates imitator. Each of these different morphs is sympatric with a different species in a different geographical region. The species with which each morph is sympatric is shown directly below that morph. From left to right, the species in (d - f ) are: Dendrobates variabilis (Tarapoto), Dendrobates fantasticus (Huallaga Canyon) and Dendrobates ventrimaculatus (Yurimaguas). Retreived from: https://www.ucl.ac.uk/taxome/jim/Mim2/dendrobates.html Date retrieved - 3/4/2019

Please join me again next week as I attempt to investigate and explain Mullerian mimicry in a specific example.



References

Merrill, R.M. and Jiggins, C.D., 2009. Müllerian mimicry: sharing the load reduces the legwork. Current Biology, 19(16), pp.R687-R689.

Motyka, M., Kampova, L. and Bocak, L., 2018. Phylogeny and evolution of Müllerian mimicry in aposematic Dilophotes: evidence for advergence and size-constraints in evolution of mimetic sexual dimorphism. Scientific Reports, 8(1), p.3744.

Sherratt, T.N., 2008. The evolution of Müllerian mimicry. Naturwissenschaften, 95(8), p.681.

TURNER, J.R., 1987. The evolutionary dynamics of Batesian and Muellerian mimicry: similarities and differences. Ecological Entomology, 12(1), pp.81-95.
 

Comments

  1. Tasmin11 April 2019 at 03:03

    Those frog mimics are amazing! Please can you explain what anti-apostatic selection is?

    ReplyDelete

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