Deadly or Delicious? Batesian Mimicry

What is the best way to remember your girlfriend’s birthday? Some might say to set a reminder in your phone or organise the flowers to be sent weeks in advance but I think you will agree that the most effective way would be to forget it once! Am I right guys? Fortunately my boyfriend has not forgotten any of those ‘vitally important’ dates and therefore escaped from being the object of my wrath but if he had of, I’m sure he would be very unlikely to forget the following year!

Some animals employ a similar strategy called aposematism (Mappes et al. 2005). This involves the prey item using bright colours to remind predators that last time they ate an animal that stood out so blatantly, like themselves, they got very sick or experienced something else that they would rather avoid than experience again. Some examples of animals using this technique are select species of frogs, snakes, wasps and bees to name a few. But not all animals with these bright colour markings are actually poisonous or distasteful to predators!

Batesian mimicry is a style of mimicry where one palatable organism mimics another species that is known to be unpleasant and unpalatable. Because the model and the mimic share the same predators and similar warning systems (most commonly aposematic colouration), the mimic relies on the predator mistaking them for the model and leave them alone (Pasteur 1982).

Honey Bee (Apis mellifera) worker beside a hoverfly
(Eristalis tenax) (Source: Warren Photographic. Image By Taylor)

One example of this is in the hoverfly. Hoverfly species mimic the colouration of bees and wasps and therefore their predators assume that they possess the same sting despite them just being a regular fly (Golding et al. 2005).

Interestingly, different species of hoverfly show slightly different colour patterns. A study by Edmunds and Reader (2013) suggested that species of hoverfly mimic different species of bumblebees. In areas where there were a high frequency of black and yellow hoverflies there was also an increased frequency of black and yellow bumblebees. Similarly, red-tailed hoverflies were commonly found in areas with many red tailed bumblebees.

References

Edmunds, M. & Reader, T., 2013. Evidence for batesian mimicry in a polymorphic hoverfly. Evolution, 68(3), pp. 827-839.

Golding, Y., Ennos, R., Sullivan, M. & Edmunds, M., 2005. Hoverfly mimicry deceives humans. Journal of Zoology, 266(1), pp. 395-399.

Mappes, J., Marples, N. & Endler, J. A., 2005. The complex business of survival by aposematism. Trends in Ecology and Evolution, 20(11), pp. 598-603.

Pasteur, G., 1982. A classificatory review of mimicry systems. Annual Review of Ecology and Systematics, 13(1), pp. 169-199.

Taylor, K., n.d. Honey Bee (Apis mellifera) worker beside a hoverfly (Eristalis tenax), photograph, viewed 26 March 2014,

<http://www.warrenphotographic.co.uk/photography/bigs/38654-Honey-Bee-and-Hover-Fly-side-by-side-white-background.jpg>

The animal kingdom’s ‘sweet transvestite’: The Female Spotted Hyena

Female spotted Hyenas are a strange. While the anatomy of striped hyenas (Hyaena hyaena) and brown hyenas (Hyaena brunnea) tend to be relatively standard, the female spotted hyena (Crocuta crocuta) throws conformity and normality out the window with their convincingly masculine genitalia (Muller & Wrangham 2002).

The female spotted hyena internal anatomy
(Source: Curious Cox. Image by Unknown)

Female spotted hyenas have a clitoris which has the same size, length and erectile ability of their male counterparts’ penises. Strangely enough, they have no external vagina and instead mate, give birth and urinate from the urogenital canal that their clitoris encompasses (proving giving birth to be very difficult indeed!) In addition to their pseudopenis, female hyenas have developed a pseudoscrotum that appears to be the fusion of the labia.

Female spotted hyenas have what is referred to as sexual monomorphism. Sexual monomorphism is rare in the animal kingdom and even rarer in species where females imitate males (Muller & Wrangham 2002). Female spotted hyenas’ genitals mimic male genitalia so well that even researchers of the species are unable to determine between the sexes of cubs until they are around three months old. Juveniles, subadults and adults are also impossible to sex unless you have an extensive understanding of the species (Muller & Wrangham 2002).

It was initially thought that this genital masculinisation was the non-functional result of unusually high levels of androgens (hormones such as testosterone and androsterone) while the cubs are developing in the womb. Although this still thought to play a role in the masculinisation of the female genitalia, it was discovered by Licht et al (1998) that initial masculinisation occurres before these hormones are activated and therefore cannot be the sole cause of masculinisation.

While it is still uncertain what has produced such an unusual trait, there are many speculations about how natural selection has played a role in producing females with such large and realistic male genitalia and how this seemingly hindering adaptation might be somehow advantageous. Muller and Wrangham (2002) suggest that it could be to defend against sibliside in the early stages of life where it is observed that females are most likely to be killed by their siblings (Frank et al 1991). The genital masculinisation may also help to reduce the chances of females becoming the target of infanticide by dominant females when they kill the cubs of lowerranking females. Yet another possible reason is to defend against intergroup aggression as it has been witnessed that females that are unknown to the clan are dealt with considerably harsher than unknown males (Holekamp et al. 1993). Each of these hypothesis are yet to be definitavely proven yet.

References

Female spotted hyena and her "Penis", n.d. photograph, viewed 17 March 2014, <http://curiouscox.wordpress.com/2012/01/11/the-spotted-hyenas-she-penis/>

Frank, LG, Glickman, SE & Licht, P 1991, 'Fatal sibling aggression, precocial development, and androgens in neonatal spotted hyenas', Science, vol 252, no. 1, pp. 702-704.

Holekamp, KE, Ogutu, JO, Dublin, HT, Frank, LG & Smale, L 1993, 'Fission of a spotted hyena clan: consequences of prolonged female absenteeism and causes of female emigration', Ethology, vol 93, no. 1, pp. 285-299.

Licht, P, Hayes, T, Tsai, P, Cunha, G, Kim, H, Golbus, H, Hayward, S, Martin, MC, Jaffe, RB & Glickman, SE 1998, 'Androgens and masculinization of genitalia in the spotted hyena (Crocuta crocuta). 1. Urogenital morphology and placental androgen production during fetal life', Journal of Reproduction and Fertility, vol 113, no. 3, pp. 105-116.

Muller, MN & Wrangham, R 2002, 'Sexual Mimicry in Hyenas', The Quarterly Review of Biology, vol 77, no. 1, pp. 3-16.

Beware of the freeloader! The Blue Alcon Butterfly

The caterpillars of the Blue Alcon Butterfly (Maculinea alcon) have the ability to mimic ants smell and sound so they can be a freeloaders in the nest before developing into butterflies.

Young Maculinea  alcon caterpillar being carried to the nest
by a worker ant. (Source: Nature. Image by Nash)

An M. alcon caterpillar starts life off in a relatively standard way by feeding on flowers of its host plants however, after three to four weeks it drops from the plant to the ground. As a result of the caterpillar’s ability to secrete hydrocarbons that closely mimic the smell of red ant (Myrmica) larvae, it is taken back to the nest by worker ants and fed and cared for as if one of their own. This approach is commonly referred to as ‘cuckoo’ behaviour (Thomas & Settele 2004, Als et al. 2004, Mouquet et al. 2005, Arnaldo et al. 2011).

While in the ant nest, it continues to mimic the smell of the larvae and also makes sounds resembling the noises the ant larvae make to beg for food. In some cases, the caterpillar even mimics the sound of a queen and receives an even higher level of care (Cobb 2009). After continued care and feeding from the ants it develops its chrysalis and later hatches and makes its way out of the nest.

Unlike the ‘cuckoo’ behaviour of M. alcon, other species such as M. arion, M. teleius, M. nausithous and M. arionides take a predacious approach. While still entering the nests by secreting an odour mimicking ant larvae and causing ants to think they are their own, these species often do not stay to be cared for by the ants. Instead they retreat to ‘safer’ areas in the nest and return periodically to feed on ant larvae (Thomas & Settele 2004).

Studies have found cuckoo feeding behaviour is present in M. alcon, M. rebeli and also a more distant relative from the Phengaris genus. Thomas and Elmes (1998) and Als et. al. (2004) state that the cuckoo varieties in Maculinea and Phengaris definitely evolved from a common ancestor and speculate that this ancestor was predacious. If this is correct, this is a demonstration of convergent evolution of these species.

References

Als, TD, Vila, R, Kandul, KP, Nash, DR, Yen, S, Hsu, Y, Mignault, AA, Boomsma, JJ & Pierce, NE 2004, 'The evolution of alternate parasitic life histories in large blue butterflies', Nature, vol 432, no. 7015, pp. 386-390.

Arnaldo, PS, Wynhoff, I, Soares, P, Rodrigues, M, Aranha, J, Csősz, S, Maravalhas, E & Tartally, A 2011, 'Maculinea alcon exploits Myrmica aloba in Portugal: unusual host ant species of a myrmecophilous butterfly in a peripheral region', Journal of Insect Conservation, vol 15, no. 3, pp. 465-467.

Cobb, M 2009, 'Caterpillars make noises like ants', The Journal of Experimental Biology, vol 212, no. 12, p. v.

Mouquet, N, Belrose, V, Thomas, JA, Elmes, GW, Clarke, RT & Hochberg, ME 2005, 'Conserving Community Modules: A Case Study of the Endangered Lycaenid Butterfly Maculinea alcon', Ecology, vol 86, no. 12, pp. 3160-3171.

Nash DR, n.d. I'll take this one home, photograph, viewed 10 March 2014, <http://www.nature.com/news/2008/080103/full/news.2007.405.html>.

Thomas, JA & Elmes, GW 1998, 'Higher productivity at the cost of increased host-specificity when Maculinea butterfly larvae exploit ant colonies through trophallaxis rather than by predation', Ecological Entomology, vol 23, no. 4, pp. 457–464.

Thomas, JA & Settele, J 2004, 'Butterfly mimics of ants', Nature, vol 432, no. 7015, pp. 283-284.

Ugelvig, LV, Vila, R, Pierce, NE & Nash, DR 2011, 'A phylogenetic revision of the Glaucopsyche section (Lepidoptera: Lycaenidae), with special focus on the Phengaris–Maculinea clade', Molecular Phylogenetics and Evolution, vol 61, no. 1, pp. 237–243.

The Art of Deception

This world we live in is full of amazing creatures that can do spectacularly deceptive things to get what they want. Whether they want to protect their young, defend their territory, to feed themselves or protect themselves from becoming food, animals have devised a myriad of methods for duping their companions (Schuiling 2004, El-Hani, Queiroz & Stjernfelt 2010). Animals use visual appearance as well as sounds, smells and behaviours in order to deceive each other and enhance their chances of survival.  (Matsumoto-Oda & Tomonaga 2005, Wickler 2013)

Over the next few weeks I will have the pleasure of introducing you to the many styles of deception, such as defensive and aggressive mimicry, automimicry, crypsis, distraction displays, and tactical deception to name a few (Vane-Wright 1976). You will also be introduced to a small assortment of the many incredible animals that perform these fraudulent feats.

References

El-Hani, CN, Queiroz, J & Stjernfelt, F 2010, 'Firefly Femmes Fatales: A Case Study in the Semiotics of Deception', Biosemiotics, vol 3, no. 1, pp. 33-55.

Matsumoto-Oda, A & Tomonaga, M 2005, '“Intentional” control of sound production found in leaf-clipping display of Mahale chimpanzees', Journal of Ethology, vol 23, no. 2, pp. 109-112.

Schuiling, GA 2004, 'Deceive, and be deceived!', Journal of Psychosomatic Obstetrics and Gynecology, vol 25, no. 2, pp. 170-174.

Vane-Wright, RI 1976, 'A unified classification of mimetic resemblances', Biological Journal of the Linnean Society, vol 8, no. 1, pp. 25-56.

Wickler, W 2013, 'Understanding Mimicry – with Special Reference to Vocal Mimicry', Ethology, vol 119, no. 4, pp. 259-269.