Butterflies as model systems

Butterflies as model systems
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Butterflies captivate out attention because of their striking colour patterns. They have been used to connect several disciplines in biology. Following are some broad areas (not exhaustive at all) which have used butterflies as model systems:

  1. Developmental biology: Development of spots on wings (developmental biology, evolutionary biology), Eye-spots: development and evolutionary significance,

  2. Anti-predator strategies:

  3. Mimicry patterns:

  4. Citizen science https://academic.oup.com/bioscience/article/65/4/419/255008

While the above-mentioned aspects are only cursory, it tells that butterflies can serve as model organisms just like the fruit fly or yeast. A small discussion at the CUBE lab today was pondering on likely questions which could be addressed using the butterfly as model systems. It turned out that there were several questions and some of them linked diverse areas from circadian rhythms, migration patterns, sensory biology to climate change. It is exciting that butterflies could tell us a lot more, beyond their bright colours patterns!

Like it? Please stay tuned for details coming soon from some enthusiastic CUBISTS…On the other hand, if anyone has any comment to be added, you are most welcome! Till then Happy CUBING and keep posting! (I could not provide reference for some topics due to the technical limit set, will add to these).

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CUBISTS went hunting for butterflies. They set up a bait trap. The bait trap is an apparatus which offers bait and attracts insects. We used fermented banana which could attract fruit feeding butterflies. Well yes, not all butterflies feed on nectar. Some also consume fruits. Catching butterflies through traps is easier than running behind butterflies! Of course, there are limitations as you would not get nectar-feeding species in your trap. However, we were eager to catch some butterflies and made a bait trap from a plastic bottle.

Within a few minutes, we found a visitor, Common Evening Brown or Melanitis leda. There were other visitors too, including fruit flies, Common Palm-fly (Elymnias hypermnestra). But Melanitis leda is striking because of its wing patterns!

What is striking about wing patterns? Well, wing patterns in Melanitis leda have been known to differ across seasons. Being a tropical species, seasons here correlate to predominantly dry and wet. The dry season (November - May) has dried leaf litter scattered around the ground floor. The wet season (June - October) has abundant green vegetation. So what has this got to do with wings?

Wings of Melanitis leda has elements called “eye-spots”. Eye-spots are circular concentric rings present near the wing margins. In the dry season, these eye-spots are reduced in size. While in the wet season they are prominent (please see dry and wet season forms of in Melanitis leda this link) What could be the significance behind the variation of eye-spot size? Melanitis leda adults feed on grasses and their life-cycle usually revolves around the ground-level vegetation. Hence there is a hypothesis that wing patterns in this species change as an adaptation to changes in background vegetation. Following is a hypothesis explaining the cause of variation.

Hypothesis: Reduced eye-spot size in the dry season would reduce the chances of detection by predators. When the butterfly with reduced spots sits against a background of dried leaf litter, it is less likely to be detected. If it has bigger spots, it will be detected faster. On the other hand, large eye-spot size during the wet season could make the butterfly conspicuous against the green vegetation background. However, the presence of eye-spots on wing margin wil cause predators to attack the wing margin. As a result, vital body parts like head, thorax and abdomen are likely to be safe.

This hypothesis was tested in an experiment which involved another butterfly species (Bicyclus anynana) also exhibiting eye-spot size variation. The predator was mantid. It was found that butterflies with larger eye-spot size were difficult to capture or attack by mantids than butterflies with smaller eye-spot size. Thus eye-spot size variation could have evolved as a selection against predators.

Eye-spot size variation demonstrates the use of butterflies as a model system to address questions in evolutionary biology/ adaptations. There could be several other possibilities. We could discuss this in the latter course. If you have any questions/ suggestions/ comments regarding this, please feel free to post!

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Image of wet and dry season forms of Melanitis leda reported in this paper Wet season morph has larger eye-spots (top left) while dry season forms (top right, bottom left and right) have reduced the eye-spot size or no spots. Please note the variation in the dry season forms.

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thanks for giving us very important and precious knowledge.
In Melanitis leda butterfly along with change in eye spot size will there be any change in colour of wings ?

@Sumasasi, we all should collectively learn.

Besides eye-spots, the background wing colouration also differs across seasons in Melanitis leda. While eye-spots is one of the elements which varies between dry and wet season morphs, background wing colours, the shape of wings are some other characteristic features differing across seasons. Please see description of wing patterns for dry and wet seasons in Melanitis leda in the paper of I mention in the earlier post (Brakefield, 1984). Also see the coloured images from the website link (ifoundbutterflies.org) I have earlier mentioned and look for dry and wet season forms.

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What is the status of Evening brown species?
What about their larvae?
Please send pictures.
What color do we expect for their pupae?
@Harshad

We had three adults of Melanitis leda collected from HBCSE campus. They have been released in a plastic box. Next day we found eggs laid on all sides of the plastic box. A grass plant was kept inside the plastic box. However, no eggs were laid on the grass plant.

Around 50 eggs were collected with a brush and placed in a plastic box with pores. Eggs hatched on the second day. Freshly hatched larvae are white. They were provided with fresh grass blade. Grass is a species of Axonopus, taken from the campus.

Pupae of this species are green in colour. We expect these pupae to be formed on leaves of the plant. We will follow up with this in later posts.

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Here are some different butterflies we all saw near our trap.

If I’m not wrong ,this one is the female Eggfly .

Well ,this one sorry but I forgot it’s name :sweat_smile:

P.S. No harm was done to the butterflies, they were handled with care.

We saw many more too like the Tailed Jay, lemon emigrant , male hypolimnas bolina, orange perriot, etc.

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Microscopic images of eggs and larvae of evening Brown.

The right one is the egg from which the larvae has hatched , while the left one has larvae still inside.

This larvae in the above picture which @Harshad sir has sent was observed under dissecting microscope. This video is of the same larvae hatching from the egg.

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Is hatching period same for all types of butterflies@sjuday2527 or do they differ from each type

  1. The butterfly in the first photo is: Male of Papilio polytes (Indian common Mormon). The female has variety in forms, like cyrus, stichius. Please see on this website https://www.ifoundbutterflies.org/#!/sp/603/Papilio-polytes. I was wrong in the identification.

  2. The butterfly in the second photo is baron, Euthalia aconthea meridionalis Fruhstorfer, 1906 – Dakhan Baron https://www.ifoundbutterflies.org/#!/sp/586/Euthalia-aconthea

  3. The butterfly in the third photo is the dorsal aspect of the common palm fly, Elymnias hypermnestra https://www.ifoundbutterflies.org/#!/sp/969/Elymnias-hypermnestra
    and the the later photo is the ventral side.

Also we saw the Indian Red Pierrot Talicada nyseus nyseus, https://www.ifoundbutterflies.org/#!/sp/743/Talicada-nyseus. There is no organge Pierrot.

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Thanks for the correction sir :heart:

Any references please? @Harshad

The reference is as follows https://royalsocietypublishing.org/doi/full/10.1098/rspb.2014.1531
It has already been posted earlier. This reference paper carries out a predation trial in the lab. This paper is just an example of the deflection hypothesis for eye-spots. Alternately there have been other hypotheses proposes.
Some argue that eye-spots intimidate predators because of their conspicuousness (http://dx.doi.org/10.1017/S1464793105006810, https://www.researchgate.net/profile/Martin_Stevens5/publication/261062216_Do_animal_eyespots_really_mimic_eyes/links/0f31753319ab484d0e000000/Do-animal-eyespots-really-mimic-eyes.pdf).

Others argue that eye-spots resemble vertebrate eyes. Eye-spots have been hypothesized to look like avian eyes or mammalian eyes (Predator Mimicry: Metalmark Moths Mimic Their Jumping Spider Predators). Thus eye-spots resemble eyes of enemies of predators attacking butterflies.

Though these explanations are likely, there has been no evidence of which predators attack butterflies in the wild and do predators get intimidated/ deflected by eye-spots?