Two Minds, One Theory

Two Minds, One Theory
Wallace & Darwin - The Two Faces of Evolution Theory

As part of the year-long events celebrating the 150th Anniversary of the Singapore Botanic Gardens, the exhibition on the Evolution Theory, first discussed by Charles Darwin and his lesser-known counterpart, Alfred Russel Wallace is currently being featured at the Botany Centre of the SBG.

The exhibition discusses Natural Selection and the Theory of Evolution as first postulated by the two intellectuals after spending a lot of time circumnavigating the globe and observing a profusion and diversity of life forms. The search for an explanation to understand long-term organic change brought them to many parts of the world then unfamiliar with the western civilisation.

Between the two intellectuals, A.R. Wallace spent many years in the Far East, collecting thousands of specimens in his research. In 1869, he published his landmark work, the Malay Archipelago, elaborating his theory of evolution. Wallace also made significant contributions to biogeography when he linked the geographical distribution of animals and plants to the regions' geological history.

Alfred Russel Wallace (1823-1913) - Ardent beetle & butterfly collector, naturalist, biologist, socialist, prolific Victorian writer, biogeographer and thinker

Whilst in Singapore, Wallace explored Bukit Timah collected 700 species of beetles. The incredible productivity at Bukit Timah is an illustration that we live in a region with one of the richest biodiversities in the world.

Amongst his collections, Wallace also collected numerous species of butterflies in the region. As a collector and a scientist, Wallace wrote in his book, the Malay Archipelago, a rather graphic and emotional account after successfully capturing the spectacular Wallace's Golden Birdwing (Ornithoptera croesus) at Batchian, Moluccas in 1858.

He noted that "On taking it out of my net and opening the glorious wings, my heart began to beat violently, the blood rushed to my head, and I felt much more like fainting than I have done when in apprehension of immediate death. I had a headache for the rest of the day. So great was the excitement produced by what will appear to most people a very inadequate cause".

Wallace's Golden Birdwing (Ornithoptera croesus) Male (above) and female (below) Plate from Reise Fregatte Novara. Zoologischer by Rudolf Felder and Alois Friedrich Rogenhofer

Wallace is also credited with describing many butterfly species for the first time, and amongst those was the famous Rajah Brooke's Birdwing (Trogonoptera brookiana) which Wallace first described in 1855.

Wallace is credited with first describing the famous Rajah Brooke's Birdwing in 1855 after a specimen was given to him by the then governor of Sarawak, James Brooke.

In recognition of his work, many later researchers also paid tribute to Wallace by naming new organisms after him. Amongst butterflies, one famous local subspecies of the Blue Pansy is the most well-known. The Blue Pansy (Junonia orithya wallacei) had the subspecies named after Wallace by the collecter Distant in 1883.

The local subspecies of the Blue Pansy was named after Wallace

The SBG Exhibition traces some of Wallace's journey in the Far East, and explains some of his theories and findings. Interestingly, he is also credited with giving the Durian, the name "King Of Fruits"! He was a converted durian eater, and actually enjoys eating the fruit that many westerners avoid.

Some of Wallace's theories on natural selection, displayed in butterflies, are mimicry, camouflage, masquerade, sexual dimorphism and so on, can be seen in Singapore's butterflies. At the SBG exhibition there are also many specimens of butterflies around the displays and nature dioramas.

At the Launch of the Exhibition, I also gave a short talk on Natural Selection, adaptation and survival strategies with particular reference to butterflies. I was honoured to have, amongst the distinguished guests in the audience, personalities like Minister George Yeo, Professor Tommy Koh and nature guru, Ms Ilsa Sharp.

The exhibition lasts until 31 Aug 2009, and for those who have yet to catch this exhibition in tribute to Alfred Russel Wallace, you have about a week more to visit the display at the SBG Botany Centre.

Text & Photos by Khew SK (except where indicated)

• Further Reading : Straits Times 22 Aug 09 : Natural History - A Common Heritage for Singapore - Dr Chin See Chung, Director/SBG

Life History of the Elbowed Pierrot

Life History of the Elbowed Pierrot (Caleta elna elvira)



Butterfly Biodata:
Genus: Caleta Fruhstorfer, 1922
Species: elna Hewitson, 1876
Sub-species: elvira Fruhstorfer, 1918
Wingspan of Adult Butterfly: 22mm
Caterpillar Local Host Plants: Ziziphus sp. (Rhamnaceae)

Physical Description of Adult Butterfly:
Above, the Elbowed Pierrot is dark brownish black with a broad white band spanning both wings. Beneath, the Elbowed Pierrot is yellowish white with a number of black spots and markings. In particular, the basal streak in the forewing is right-angled, and appears to link up with the basal streak in the hindwing. Each hindwing has a slender white-tipped filamentous tail at the end of vein 2.


An Elbowed Pierrot visiting flowers in the nature reserve.


An Elbowed Pierrot puddling on wet grounds.


An Elbowed Pierrot resting on a perch.

Field Observations of Butterfly Behaviour:
This small-sized species is rather common in the nature reserves of Singapore. The adults are often found flying close to the ground and settled at moist spots on the forest floor. On sunny days, they can be found to visit flowers, and the males have been observed to puddle on bird droppings.

Early Stages:
The local host plant, a Ziziphus sp., is a thorny straggling shrub with simple, alternate and ovate-lanceolate leaves, each of which has three prominent nerves and finely toothed along the edge. Young leaves are light brown to reddish brown, and turning green when mature. All four instars of the immature stages of the Elbowed Pierrot feed on the young brownish leaves, and the green leaves when they are still relatively young and tender.


Host plant:a Ziziphus sp. Young shoots.


Host plant: a Ziziphus sp. Close-up shots of young and mature leaves.


A mating pair of the Elbowed Pierrot.


Elbowed Pierrot mothers' attempts to lay eggs on the leaves of the host plant.

Eggs of Elbowed Pierrot are typically laid on young shoots or leaves of the host plant. The small egg is disc-like (about 0.5mm in diameter) with a depressed micropylar. When freshly laid, the egg is yellowish green. The color soon decolorizes to light green within the next few hours, and then to white overnight as it matures. The surface is covered with a reticulated pattern of intersecting ridges.


Two views of an egg of the Elbowed Pierrot. Diameter: 0.5mm.



Left: mature egg showing the caterpillar eating away the egg shell for its exit.
Right: empty egg shell.

Each egg takes 2-2.5 days to hatch. The young caterpillar emerges after nibbling away sufficiently large portion of the egg shell. Measured at a length of about 0.9mm, its pale yellow body is cylindrical in shape, sporting long fine setae (hairs) and a brown head capsule.


Top: a newly hatched caterpillar, length: 0.9mm.
Bottom: 1-day old caterpillar, length: 1.2mm.

The newly hatched grazes on the surface of young leaves. As it feeds and grows, its body takes on a greenish undertone. After 2 to 3 days of growth, it looks pumped up at a length of about 2mm. After a period of immobility of about half a day, it moults to the 2nd instar.


1st instar caterpillars. Top: 2-day old, length: 1.5mm.
Bottom: late in this stage, length: 2mm.

Covered with numerous setae, the body of the 2nd instar caterpillar could in either light yellowish green or pale pinkish coloration. Setae found at the dorsal and lateral margins are longer and stiffer. The body is flatter compared to the 1st instar caterpillar, and faint dorsal bands whitish in color are discernible.


2nd instar caterpillars. Top: newly moulted, length:2mm.
Bottom:late in this stage, length: 3.5mm.


Top: late 2nd instar in pre-moulting dormant state.
Bottom: newly moulted 3rd instar caterpillar.

The 2nd instar caterpillar reaches a length of about 3.5-4mm, and after about 3 days in this stage, it moults again. The 3rd instar caterpillar has numerous short and fine body setae. The two whitish parallel dorsal bands, flanked by two thin and deep green bands, are now rather pronounced, The 3rd instar takes 3-4 days to complete with the body length reaching about 6.0-7.0mm. There is no obvious sign of any nectary organs, which are common in many other lycaenid species, on the 7th and 8th abdominal segments,


3rd instar caterpillars. Top: early in this stage, length: 4mm.
Bottom: late in this stage, length: 6mm.

The 4th (and final) instar caterpillar is similar in appearance to the 3rd instar caterpillar with one main difference being the apparent merging of the two dorsal bands into a single broad band. The body segments appear to be translucent, in either light green or pale pinkish coloration. The body shape deviates from the usual onisciform shape in being much flatter with a large prothorax.


4th instar caterpillars. Top: middle-aged, pink form, length: 9.5mm.
Bottom: late in this stage, green form, length: 12mm.

While some members of the Caleta genus (such as Caleta roxus) do not carry any nectary organs in any instar, the Elbowed Pierrot has a slit-like structure on the 7th abdominal segment in the final instar. With no ant attendance observed in the field, it is likely to be a non-functional dorsal nectary organ. In addition, no tentacular organs can be found on the 8th abdominal segment.


A likely non-functional dorsal nectary organ on the 7th abdominal segment of
a final instar Elbowed Pierrot caterpillar.

After 5-6 days of growth and reaching a maximum length of around 12-13mm in the final instar, the body of the caterpillar gradually shrinks, and finally takes on a pale reddish brown coloration. All bred specimens chose to enter their pre-pupatory phase on a spot on the leaf surface. At the chosen site, the caterpillar readies itself for pupation by spinning a silk girdle and a silk pad. The caterpillar secures itself to the silk pad via claspers on its posterior end.



Two views of an immobile pre-pupatory larva of the Elbowed Pierrot.
The silk girdle can be easily seen.

Early stages of the Elbowed Pierrot.

Pupation takes place after one day of the pre-pupal stage. The hairy pupa has the typical lycaenid shape, being somewhat flatter and having a broader abdomen. It is pale brown in the abdomen, dark brown on the thorax and beige in the wing pad areas. The pupa has a length of about 8-9mm.


Two views of a pupa of the Elbowed Pierrot, length: 8mm

Six days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. The prominent white bands on the forewing uppersides become visible through the pupal skin in the wing pads. The next day the adult butterfly emerges from the mature pupa.


Two views of a mature pupa of the Elbowed Pierrot.


A newly eclosed Elbowed Pierrot


A newly eclosed Elbowed Pierrot perching near its empty pupal case.


References:

• The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
• The life history of Caleta roxus, Konrad Fiedler, Nachr. entomol. Ver. Apollo, N.F. 14 (4): 371-384, Jan. 1994.

Text by Horace Tan, Photos by Anthony Wong, Benedict Tay, Sunny Chir and Horace Tan

We Are One!

We Are One! - Butterfly Lodge is One Year Old

It has been a year since the launch of the Butterfly Lodge at Oh’ Farms on 9 Aug 2008. Last Sunday, on the day when Singapore was celebrating its 44th National Day, our friends at Butterfly Lodge, members of Butterfly Circle and a few invited guests also had a gathering to celebrate Butterfly Lodge’s first birthday!

We spent the evening in a very casual and carefree setting, chatting and sharing stories about butterflies (of course!). Amidst the laughter and bantering, we could hear the low-frequency throb of helicopters in the nearby skies, returning from the National Day Parade at Marina Bay. With the constant supply of good wine, drinks, beer and delicious food, all of us were so engrossed in our conversations and eating that we did not remember to snap even a single shot. What a pity !

Yeok Keong, the owner of Butterfly Lodge at Oh’ Farms also presented tokens of appreciation to members of ButterflyCircle who had helped in the initial planning and setting up of Butterfly Lodge. The pictures below show some of the A1 size posters outside the butterfly flight cage (photos on the posters were contributed by ButterflyCircle members).

Being the only one of its kind here, Butterfly Lodge features only common local butterfly species with the main aim of promoting butterfly appreciation and awareness amongst school children. We are proud to report that within a year, about 5000 visitors (mainly from Child Care Centres, Pre-schools and Primary Schools) have visited Butterfly Lodge and attended an introductory lesson related to the life cycles and behaviour of butterflies.

We are glad to say that ButterflyCircle and Butterfly Lodge have created opportunities for kids here to observe the activities in a typical day in the life of a butterfly, such as feeding, sunbathing, performing courtship dance, mating, and laying eggs, up close and personal, creating lasting learning interactive experiences for the kids.

How many students these days have the chance to see mating butterfly ? At Butterfly Lodge, visitors can very often observe a live scene of what mating is all about. This presents a very good teachable moment of explaining how a new life begins to our young children.



In the enclosure, students may be lucky enough to witness a weird behavior of how a female would reject mating by pointing her abdomen upwards as shown in the picture here.

Indeed, we are delighted to learn that some of our young visitors are now able to recognize and identify the butterfly species flying around in their neighbourhoods after their visit to Butterfly Lodge.

While playing the role of supporting Butterfly Lodge in various areas, ButterflyCircle members also gained valuable learning experiences and insights on the biology and ecology of butterflies during the past one year. Here are some examples :

One whole batch of Plain Tiger (Danaus chrysippus chrysippus) larvae were found dead overnight after they were fed with Crown Flower (Calotropis gigantea) leaves supplied from a neighbouring country. We suspected that the leaves might have been contaminated with chemicals that we were not aware of . Butterfly larvae are very susceptible and vulnerable to toxins - even a trace amount of toxin is enough to kill all of them.

There was an initial success of breeding the Blue Pansy (Junonia orithya wallacei) in captivity, resulting in good numbers of Blue Pansys in Butterfly Lodge. However, they did not proliferate further after one or two generations. Subsequently, despite a few times of introductions of both male and female Blue Pansys into the enclosure, we have not seen caterpillars yet. We suspect that certain unknown factors in the enclosure environment may have prevented Blue Pansys from mating or laying eggs.

Both the male and female Blue Pansy are very pretty and attractive. We will continue to monitor the breeding progress for this species.

One pair of Jacintha Eggfly (Hypolimnas bolina jacintha) was introduced into the enclosure in Aug 08. The species was doing very well during the first few generations. But, again the number of Jacintha Eggfly larvae dropped drastically over a period of 2 to 3 months. Since late March 2009, there was not a single Jacintha Eggfly left. So we suspect that inbreeding may have a role in causing infertility in the species.

A new female form of Jacintha Eggfly?

Furthermore, we also observed that a small number of female Jacintha Eggfly in the last one or two generations displaying unusual markings as shown in the picture. Was it due to inbreeding or is there really such a new form that has not been observed before?

It was a pleasant discovery that Peacock Pansy utilizes Strobilanthes cubia as a preferred larval host plant in the enclosure despite the presence of Red Flame Ivy (Hemigraphis alternate) and Ruellia repens which are its known host plants in the wild.


A Peacock pansy caterpillar in its pupation position and the newly discovered host plant, Strobilanthes cubia

In addition, it was also observed that without enhancing the gene pool with new introductions from outside the flight cage, low fertility rate also affected the population of the Peacock Pansy (Junonia almana javana).



Lastly, we also discovered that the life span of some species such as Common Mime (Chilasa clytia clytia ) and Common Birdwing (Troides helena cerberus) was very short (less than a week) in captivity. So these species are not suitable for captive breeding unless the flight cage is high and big enough for them to roam freely.

Apart from some minor setbacks, generally, it has been a very successful year for Butterfly Lodge. Looking forward, Butterfly Circle and Butterfly Lodge will continue working together to educate more children and the public in butterfly appreciation. With more people being butterfly-literate, many flying jewels should soon be fluttering in our natural environment for our next generation to appreciate. We are also confident that what we have learnt in captive breeding will help in the conservation of some butterfly species in the future.

Text by Federick Ho ; Photos by Neo Ai Ling & Federick Ho