Blog Post 8 - Automimicry


In this week’s post I will introduce the concept of automimicry. Many prey species carry primary defences like warning colouration and secondary defences such as toxins and stings, which are harmful to predators, but cannot be detected by predators before the prey is captured (Svennungsen and Holen, 2007; Ruxton and Speed, 2006).  Predators that attack defended prey usually learn to avoid similar-looking prey by associating the prey's visual characteristics with its defence. Because the warning signal is typically structurally unrelated to the secondary defence, it is not necessarily an honest indicator of a prey's true defence level. Therefore, secondary defences are readily exploitable by undefended ‘cheats’ that carry only the deceptive warning signal (Svennungsen and Holen, 2007). Such exploitation is illustrated in the previously discussed concept of Batesian mimicry, where one or several undefended species benefit from mimicking the appearance of a defended model species. Another intriguing possibility, which is the focus of this blog, is that of automimicry, in which some fraction of the individuals in a defended species produces little or nothing of the defence, but nevertheless obtains some protection from predation because they are identical in appearance to their defended conspecifics (Speed et al. 2006).

In automimicry, the replication of patterns present in conspecific individuals at homologous sites or elsewhere in the body can take a few forms. It can occur through behaviour where an individual will mimic the gestures of another class of individuals, and it can also occur through morphology where colour patterns and threatening body parts are repeated and used for intimidation and defence (Guthrie and Petocz, 1970). Automimicry seems to follow the concept of one works well, and two work even better (Guthrie and Petocz, 1970). So basically, as long as an automimic prey species looks and acts like it has that secondary defence, even though it doesn’t, it is usually avoided by predators.

There are many examples of automimicry. Some include the gray hairstreak butterfly (Strymon melinus) which have a false head at the base of their wings deflecting attacks from the actual head. The foureye butterflyfish (Chaetodon casistratus) mimic their own eyes on their back to also deflect attacks from the vulnerable head. Also many males of various bee and wasp species, although defenceless, are protected from predators by their resemblance to females that are equipped with stingers.

The gray hairstreak butterfly (Strymon melinus) Source: https://en.wikipedia.org/wiki/Automimicry#/media/File:Gray_Hairstreak_(One_more_time...)_(6222138633).jpg Retrieved on: 03/05/2019
 
The foureye butterflyfish (Chaetodon casistratus) Source: https://en.wikipedia.org/wiki/Automimicry#/media/File:Chaetodon_capistratus2.jpg Retrieved on: 03/05/2019


References



Guthrie, R.D. and Petocz, R.G., 1970. Weapon automimicry among mammals. The American Naturalist, 104(940), pp.585-588.

Ruxton, G.D. and Speed, M.P., 2005. How can automimicry persist when predators can preferentially consume undefended mimics?. Proceedings of the Royal Society B: Biological Sciences, 273(1584), pp.373-378.

Speed, M.P., Ruxton, G.D. and Broom, M., 2006. Automimicry and the evolution of discrete prey defences. Biological Journal of the Linnean Society, 87(3), pp.393-402.

Svennungsen, T.O. and Holen, Ø.H., 2007. The evolutionary stability of automimicry. Proceedings of the Royal Society B: Biological Sciences, 274(1621), pp.2055-2063.

Comments

  1. Tasmin7 May 2019 at 23:29

    Automimicry seems to be quite a curious thing. I assume it’s something to do with underlying genetic changes that result in the secondary defence (e.g. the toxin) not being expressed?

    ReplyDelete

Post a Comment

Popular posts from this blog

Image
Blog Post 6 - Aggressive Mimicry So far, I have explored defensive mimicry in animals, specifically Batesian and Mullerian mimicry. In this week’s post I will explore aggressive mimicry. As introduced in my first blog, aggressive mimicry is a form of mimicry in which predatory organisms share/mimic similar signals to that of a harmless model, which allows them to avoid being correctly identified by their prey or host (Jackson and Cross, 2013). This form of mimicry can be compared to “a wolf in sheep’s clothing” strategy. Aggressive mimicry has evolved to improve foraging success (Glaudas and Alexander, 2017). It has been seen to involve various sensory modalities such as visual, acoustic, chemical, and vibrational, and it usually involves a single signal or variants of that signal (Glaudas and Alexander, 2017; Wignall and Taylor, 2010).   Above is a classic example of aggressive mimicry. Lophiiformes or angler fish as they are more commonly known, use a visual form ...
Read more
Image
Blog Post 3 - Batesian Mimicry in Papilio polytes This week I will be using the swallowtail butterfly, Papilio polytes, as an example of Batesian mimcry. The swallowtail butterfly is common throughout Asia and is known to resemble the unpalatable red bodied butterfly, Pachliopta aristolochiae (Katoh et al. 2017). In the swallowtail butterfly there is a single male isoform and two different female isoforms; Interestingly, only the female forms can mimic the red bodied butterfly ( Nishikawa et al. 2015) . Females occur either in the form of:                                                                               ...
Read more
Image
Blog Post 9 – Automimicry Explained Further  & an Example It is widely assumed that prey were cryptic and defended before evolving some kind of warning signal. However, focusing on the mechanisms that drove the evolution of defensive display may prevent examination of a pivotal event in the evolution of aposematism, the evolution of the secondary defence that is to be displayed (Speed et al. 2006). Secondary defences can be costly to generate and maintain so their evolution may need special consideration (Ruxton and Speed, 2005; Skelhorn and Rowe, 2007). If defences often evolve before aposematic displays in prey animals, there is a paradox: why should prey invest in costly secondary defences if they are already well-protected by crypsis? (Speed et al. 2006). Two general explanations can resolve this issue. The first is via preadaptation. A prey species may already possess a trait that happens to provide some protection against a predator (Speed et al. 2006). For exa...
Read more