Indian Wildlife Club Ezine (November, 2016)

-Jayshri Dumbre

Duration: 8th to 14th October 2016

It was "call of the forest" and I got the opportunity to do patrolling activity of Bhimashankar forest area for entire seven days. 

"Each day provides its own gifts"- a quote by Marcus Aurelius came to alive for me in those seven days. I was truly excited for the forest walk and did not wanted to lose a single moment of it after waiting for nine months for this opportunity. 

It was a sheer joy and bliss to wander in dense forest just after the monsoon. We were lucky for not having rain during entire period of this activity. It wasn't too sunny, hence we could do patrolling activity in pleasant weather.

The entire Bhimashankar Wildlife Sanctuary is divided in two parts namely Bhima - 1 and Bhima - 2 for better management and control. We were four volunteers to join for the program for this batch. We all travelled to Murbad district location to report to Bhima-2 forest office from our respective locations. We completed official formalities in the forest department office as instructed. We also received a brief instructions and general plan of activities that we were supposed to conduct in next four days in order to cover Bhima-2 forest area. We reached Forest Rest House, Nariwali village by state transport bus (MSRTC) in the evening and could take a small forest walk nearby up to village river before the sunset. Mr. Thakare was the caretaker of the rest house who was also a resident of the village. We stayed at the rest house for next four days and had tasty food at Mr. Thakare's home.

After having breakfast in the morning, we travelled to Khopiwali village. The forest guard, Mr. Raju accompanied us for the day. Our trek to Gorakhgad pinnacle started from Khopiwali. Raju has immense amount of stamina and its him due to which the day was adventurous. Although I had done this trek just 7 months earlier, it was still thrilling to climb the pinnacle again. We visited Sondi waterfall on our return. The waterfall was giant and we couldn't dare to go any closer to it. We could cover beat no. 748 and 750 in this day.

Golden Orb Spider

Few lizards and bats were seen at Gorakhgad. The various species of earthworms, crabs and frogs were abundant. Butterflies and flowers were everywhere.

On our way to return we could spot the Golden Orb Spider (Nephila pilipes).   It is probably best known to the public for its ability to build large, spectacular webs with spider silk that is stronger than kevlar. However, although large webs might mean more prey caught, the trade-off would be its susceptibility to parasites. Like all spiders from the family Nephilidae, female gigantism is extremely pronounced and this results in the large sizes of mature female spiders, achieving body lengths of 40mm to 50mm. 

 

On third day, we started early morning to cover the entire forest area of beat no. 749. We had planned our day in order to stick to flat terrain of forests and avoided any steep ascent. Mr. Vilas, Forest Guard, was accompanying us on this day and our first spot to visit was Subhedar waterfall. 

Bronzed -back Mantella frog

On our way to waterfall, we saw Bronzed-back Mantella frog. There are about 220 species of Poison Arrow Frogs and Mantella belongs to this family. This a small, terrestrial frog normally found in rainforest. The Bronzed-back Mantella is named specifically because of its bronze stripe which lines its back and travels through to the tip of its nose covering the rim of its large eyes. The Bronzed-back Mantellas are small, reaching a size of 2.5 centimetres (1 inch) in length. 

The Subhedar waterfall was marvellous and high enough, although best part was it is untouched. There were no other tourists and we were the only one to enjoy the place fully. The water was cold and was shallow so that we could enjoy to the fullest. We had a bath in the waterfall followed by some photography and then we moved to our next destination 'the river point' by the lunch time. After the lunch at river (which tasted just yum), we traced the Sidhhagad platue and returned back to Narivali by another route instead of returning by the same route we came. Sidhhagad platue and return journey was longest and took approximately 5 hrs of trekking. We were extremely tired on this day that we slept immediately after the dinner.

On this day, we were supposed to reach to Bhima-1 office by trekking; however, since the staff was on holiday on the occasion of Dasara, we were asked to stay back at Nariwali by Bhima-2 RFO. Mr. Thakare himself made our forest walk arrangements on this day and accordingly, we visited Jambhurde dam after the breakfast and covered a small part of forest adjoining the dam. We had late lunch after coming back to Nariwali and had rest thereafter.

RFO, Bhima-2 arrived Nariwali and had a detailed discussion with us about our next plan. As instructed, we trekked to Ahupe village from Khopiwali via the famous Ahupe Ghat route with Mr. Raju. We observed an unique species of chameleon on the way.

Indian tiger centipede

 A colourful Indian Tiger centipede (Scolopendra hardwickei)  got our attention while walking. One of the bright coloured creature which looks very beautiful. It can deliver a painful venomous bite which is a clear cut message from the orange and black strips. It's venom is very potent and can cause extreme pain, swelling and aches in humans.  Our trek was hectic as we gained the maximum altitude on this day. We also had our backpacks with us as we were shifting our base from Nariwali to Ahupe. It took almost 5 hrs to reach Ahupe. We reached there in the evening but the forest guards had no information about our arrival. However, Mr. Kede managed our stay and food arrangement for the day. He also finalised one forest guard to accompany us for our next day trek. We stayed at Forest Vanarakshak office and had food arrangements at Mr. Kede's home.

We started for Kondwal village with Mr. Laxman Lange, Forest Guard, after the breakfast at Mr. Kede's home. The trek was easy without any hard ascent or descent. Although we had our backpacks with us, this was the least tiring trek. We trekked via Bhatti Forest and then half of the walk was via road head. We observed several wild monkeys on this road-head which made this trek memorable. Kondwal village was the real treat. We enjoyed the Kondwal Forest walk in the evening time with Mr. Pandu Damse who took us in the dense forest where hardly any path was visible. We spotted Shekaru (Ratufa Indica - the big giant squirrel) and their nests and visited several beautiful water streams. This forest was also seemed to be best for various flowers and butterflies species.  We visited Kondawal waterfall on return journey and spent some time there in peace while it turned dark. Our stay and food arrangement was done at Mr. Damse's home and we were pleased to receive very tasty food and hospitality. 

We started our day very early morning to spot few wildlife. We covered entire Ghatghar forest area which included crossing of multiple river streams. The Ghatghar forest is really dense and full of beauty. We spotted various birds, shekaru, snakes, pugmarks of deer and scratch marks of leopard. 

Common Jezebel

I captured Common Jezebel (Delias eucharis) butterfly in my camera. They are very colourful having hues of yellow, red, black and white. Typically the upper side is white with well defined black veins and the underside having a similar pattern in addition to the hind wings having a bright yellow with a series of red spots. Both the male and female look very similar with only few differences. It is found to frequent a wide variety of habitats including tropical rain forests, open woodlands and flower gardens and can be seen in most parts of the islands.

Tree snail

The image shows a tree snail descending down a rough wooden structure. The land snails too are abundant in this forest.

After having continuous long walk for approximately 7 hrs, we decided to return to have our late lunch. Post lunch, we initiated our journey to Bhima - 1, Forest office and reached there in the evening by 6:00pm with Mr. Damse. However, the staff had already left for the day and we couldn't detail out various options available to us. It was anyway our last day of patrolling hence we decided to return back to our respective hometowns. We handed over our reporting documents to Mr. Damse for completing the reporting formalities at office and left for Pune by MSRTC bus.

During patrolling, the information on various flowers/trees and their use, characteristics received from forest guards was very useful. The program could been more systematic if IWC and Forest Department could have provided us a more detailed schedule for seven days to avoid randomness and coordination related issues. 

Overall a mesmerising experience in the lap of nature and I strongly recommend this program for all the nature lovers out there.

(Jayshri Dumbre is a metallurgist by profession.  She is also a passionate mountaineer and trekker, who has completed Advanced Mountaineering Course from the National Institute of Mountaineering (NIM), Uttarkashi) 

Staying well out of sight

Being transparent is sometimes not sufficient to be invisible, says S.Ananthanarayanan

Taking on the colours of the surroundings is a good way to avoid detection. However, this may not work when one is in featureless surroundings. In such a case, what is needed is to be transparent. Even so, being transparent helps mainly when one is lit from behind and not quite as well when lit from the front. This is because there is almost always a bit of light that transparent surfaces reflect, which would give the transparent object away.

Laura E. Bagge, Karen J. Osborn and Sönke Johnsen from Duke University, North Carolina and the Smithsonian National Museum of Natural History, Washington DC, report in the journal, Current Biology, the adaptation by a class of sea water dwelling organisms to minimize reflection of light by their body surface, as a means to avoid detection.  

 The animals studied are a group called hyperiids, which inhabit the upper column of sea water, short of deep water, and are covered by a light shell.  The organisms are generally transparent. However, as the downward illumination at the depths where the animal is found is much greater than horizontal illumination, even a small extent of reflection by the animals would make them stand out when viewed horizontally. The animals have thus been under evolutionary pressure to minimize the level of reflection by their surface.

The reason that transparent surfaces also reflect part of the light that falls on them is that there is a change in the speed of light when it passes from the surrounding to the  transparent material and again when light passes out, to the surroundings.  The speed of light in a material depends on the way the material supports electric and magnetic variations that light consists of.  The abrupt change in these properties when light passes from one material to another results in part of the energy not being transferred into the material but sent away as a reflection.  One way of reducing the reflection from a surface would hence be to create conditions so that the change in the speed of light is not abrupt, but a little smoother.

The Current Biology authors report that they used a scanning electron microscope to investigate the skin surface of seven varieties of hyperiids and discovered features, which have not been documented so far, which may be the way reflectance is reduced from these surfaces. The researchers found that the skin on the legs of one form of hyperiid is covered by nano-protuberances some 200 nm in height and the skin of this and the other hyperiids also had a layer of spheres, in the same range of dimensions.

The paper notes that the effect of such protuberances of dimensions less than the wavelength of light was first observed in the case of corneas of moths and some butterflies. Moths usually come out at night and to be able to see, they need to let in as much of the light that comes to their eyes as possible. The cornea, or the outer layer of their eyes, which has thus evolved to minimize reflection, and maximize transmission, also has protuberances of sub-wavelength dimensions. The minimized reflection also serves to make the moth more difficult to detect, in the dark, which protects it from predators. It was also later found that the wings of the moth and cicadas have a microstructure so that the area of chitin (hard tissue) the light strikes increases as one gets nearer the surface, the paper says. 

A gradually changing structure, at a size less than the wavelength of light results in gradual change in the speed of light waves and hence greater proportion of light being transmitted, as opposed to reflected. The paper mentions that the theoretical reduction in reflectivity, based on the dimensions of the surface structure, is verified in practice and experiment. The researchers found that the legs, which account for most of the surface area of one variety of hyperiids, were almost fully covered with an ordered, periodic array of nano-protuberances, 200 nm high and spaced 96 nm apart and conical in shape, just like what is seen on the transparent wings of insects and corneas of moths.

 

The paper notes that a thin transparent layer where the speed of light is in between the speed on the two sides of a surface, could be arranged, depending on the wavelength of the light that was falling, to completely eliminate reflection. This property has been made use of to cover lenses used in the laboratory or industry, to reduce reflection at the surface. While instances of this device have not been seen in nature, the paper says, most of the body skin of the hyperiids were covered with a dense monolayer of identical spheres, which appeared to be layer of a form of bacteria.  X Ray analysis showed that the material was all organic and some of the spheres, which were not part of the skin but external attachments, also seemed to be undergoing division. These spherical bodies measured from 52 to 320 nm, which would affect reflectivity and appeared to be acquired from the environment.

Further analysis showed that the nanostructure clearly reduced reflectivity of the surface, particularly when light fell at glancing angles and was more likely to be reflected. A clean, smooth skin surface was found to have reflectivity of 0.6 to 1% when light fell squarely on the surface, increasing to 7% to 75% at glancing angles.  With the nanostructure, however, reflectivity was less than 0.5% for a broad range of wavelengths and angles of incidence.

 

Helper  bacteria

Another instance of bacteria help organisms stay unseen is in the case of the Hawaiian Bobtail squid or the Flashlight Squid. While foraging at night in the shallow Pacific Ocean (and some parts of the Indian Ocean), the squid presents a silhouette or shadow against the moonlight or starlight, to predators below, and becomes a sitting duck target. The squid has evolved to support a colony of light emitting bacteria, called Vibrio Fischeri, which live off the sugar and amino acid nutrients from the squid, and repay by getting luminescent, as and when required, for the host to hide its shadow.

 

Increasing reflectivity

A converse of the strategy described so far is employed by some silvery fish, like sardines, carp and mackerel, to stay out of sight in well lighted waters. Although their scales reflect diffuse light, to match the background, there is a property in reflection which makes the light a little dimmer, on reflection.  It has to do with light being electrical and magnetic vibrations, in all planes transverse to the direction of motion of the light. On reflection, certain planes are reflected more easily than others, leading to a drop in intensity. These fish have a multilayered and transparent microstructure in their scales so that transmitted light is channeled to reflect and compensate for the loss. The light coming off the fish is hence of the same intensity as the light that fell on it and that is there in the surroundings, and the fish stays out of sight!

[the writer can be contacted at response@simplescience.in]

-Susan Sharma

One of the major reasons for the increased pollution levels in land locked cities like Delhi and Gurugram , has been identified as agricultural crop burning.  A brief research on the Internet gives us research reports and practical measures tried and tested elsewhere.  These can be implemented all over India by agriculturists with very positive outcomes. 

In the recent past some bright minds working as part of State Bank of India Youth for India fellowship program , have gone deeper and implemented successful projects in the area of agricultural farming, worthy of emulating.   Two blogs which I found on the SBI Youth for India Blog mention the possibility of reducing farm and forest emissions, if only awareness and some amount of hand holding is available in rural areas.   Links to these blogs are given below.

Excerpts from a fellow’s Diary – Farming Needs Improved Techniques

Posted on June 11, 2014by SBI Youth For India

Amrita Bhattacharya talks about avoidable forest fires

Living in the fire and haze
https://sbiyouthforindia.wordpress.com/2016/05/13/living-in-the-fire-and-haze/

Posted on May 13, 2016by SBI Youth For India

SBI YFI fellow Taher, writes about working with farmers on soil solarisation project. Traditionally, farmers prior to sowing the seeds would prepare the ground by piling leaves, biomass and forest wood up to a height of 2-3 feet and then burning it as they believe it destroys the weeds and leads to healthy plants. Paddy is then sown after the first shower. Approximately 750-800 kg of bio-mass is used for 1/4 acre. Apart from the damage to the environment and pressure on forest resources, it is a laborious process, involving 3-4 months of activity. Through soil solarisation process, the ground is prepared by spreading a layer of cow dung or vermi-compost or ash from domestic fires and then covering it with a plastic sheet for about 20 days. After this, with the first showers the paddy is sown. The results have been encouraging and farmers are getting convinced about the merits of this process.

Taher Sarthawala worked  with BAIF in Lachakadi in Gujarat.   

Plastic sheet therapy for crop residues

Here is an excerpt from his blog, which documents the initial struggle in changing mindsets. 

Later he presented his views during our exposure visits. He said,“Now is the time to move away from our traditional methods towards new-and-improved techniques. If we don’t, then agriculture will no more be a viable option and we will have to look elsewhere for our livelihood. Using this new method, the quality of seedlings is better, with more leaves and absolutely no weeds. The SST technique requires lesser time and saves us the drudgery of having to go into the jungle in search of biomass.”

The astonishing results took the farmers by surprise. Ironically, fields that had been treated with Rabb, which was supposed to kill weeds, had more weeds than those that had solarized soil.

The results from the SST technique not only attracted farmers from other villages but also forest officers, who were having a tough time dealing with the traditional method, due to which the forests were losing their green cover. The new technique impressed the forest officers to such an extent that it got sponsorship from the Forest Department."

An excerpt from Amrita Bhattacharya's blog reads

"The forests in and around the area I live in Uttarakhand Pithoragarh Berinag Forests is on fire for close to a month, only now I have seen some posts in the media about the devastating fires that are raging in Uttarakhand. Reportedly nearly 1900 hectares of forest land has been destroyed and the fires still continue to rage engulfing the region in a haze of smoke. The locals say it has not been this bad in a long time, as the dry pine needles prone to fires are still more vulnerable in the drought like state where it has not rained for past several months.

The concern is even more when you find out that the fires are often man made and intentional, showing a serious apathy towards the very forests that maintain the ecological balance of the mountains.

The pine trees which are often tapped for resin, is anyway left weak and the inflammableres in exposed on the bark. These trees after they are burnt in forest fires dry up and are cut and sold."

Forest fires

Pollution due to crop burning is not just India's problem but a universal one.  Many developing countries faced it, but found alternatives for this "short cut" in farming practices.  

1. Burning wheat residue results in a loss of nearly all the nitrogen and approximately half of the sulfur and phosphorus present in the residue. 
2. Research shows that standing wheat stubble helps store 76% of over-wintering precipitation compared to 57% when the stubble is burned in the fall.
3. Generally, every inch of water stored produces from 5 to 7 bushels of grain per acre. 

In the year 2004, the State of Washington , Department of Ecology Air Quality Program prepared a detailed report entitled "Agricultural Practices To Help Eliminate or Reduce The Need to Burn"

The report observes 

 “Burning has been used as a quick residue removal tool. Long-term, repeated field burning along with tillage has been shown to be detrimental to soil productivity. 

However, burning might be a limited tool to manage excess residue and Increased public concern and compliance with air quality regulations also must be considered. “

 “Before using fire as a tool, growers should consider other management practices and factor in economics together with environmental impacts on water conservation, erosion control, and air quality, when making decisions on which to use.”

At harvest, the stems, stalks and leaves from a newly harvested crop are left in the field.  This 

1.Protects the soil from erosion by wind and rain

2.Reduces water run off from the fields during the rains.

3.Conserves water

4.Adds organic matter to the soil.

5.Reduces labour, fuel and equipment wear.

6.Provides habitat for wildlife.

7.Reduces release of carbon gases.

At planting, instead of disturbing (plowing or tilling) the whole field, seeds are planted in very small grooves or strips.  This keeps most of the old stems, stalks and leaves (crop residue) intact on the soil surface to protect the soil while new plants are growing.

Hill pollution

Organic farming system is a method of farming system which is primarily aimed at cultivating the land and raising crops in such a way, as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm wastes, aquatic wastes) and other biological materials along with beneficial microbes (biofertilizers) to release nutrients to crops for increased sustainable production in an eco friendly pollution free environment. It is a method of crop and livestock production that involves much more than choosing not to use pesticides, fertilizers, genetically modified organisms, antibiotics and growth hormones.

Organic production is a holistic system designed to optimize the productivity and fitness of diverse communities within the agro-ecosystem, including soil organisms, plants, livestock and people. The principal goal of organic production is to develop enterprises that are sustainable and harmonious with the environment.

One of the practices for Organic farming is Penning. Penning is done with herds of either Sheep or Goat. Sheep / Goat penning is one of the traditional methods of enhancing soil fertility. Penning is an important part of Organic Farming. In this process the sheep are made to stay in the field overnight which enables its fecal matter and urine are left in the field later incorporated to a shallow depth by working blade harrow or cultivator or cultivator.

The sheep get their feed from field and field is enriched with nutrients and loads of micro organisms act on them to turn the soil more fertile than before. As the activities of various organisms increase in the soil makes it more porous. The physical properties of the soil are found to be greatly improved after every penning.

The number of sheep / goat in one flock varies from 100s to 1000s. The penning starts in the evening where the sheep / goats are made to assemble in a selected field. They are brought in such a way the kids are with mothers. Penning is found to turn soil into more fertile than before and any crop can be grown after sheep penning. Also the root grub dies due to the power of sheep urine. The urine reduces salinity in the soil. Grazing of the sheep / goat in the field helps the field with fewer weeds which would have turned into menace.

The farm produces are found to be of good quality and tastier compared to produces from non-penned fields. The weight of the grains from the penned fields is more.

((Text and photographs by Amina Bibi.  K. Amina Bibi is a Post Graduate in Agriculture with specialization in Plant Breeding and Genetics. She is currently working as Agriculture Officer in Karaikal, Department of Agriculture, Government of Puducherry) 

The dwindling owl population a concern.

-Ajay Gadikar

Owls are revered as the carrier of Lakshmi, the deity of wealth. However, at the same time, owls are feared as the symbol of ill omen in several literary texts. Come Diwali and a vast number of owls are caught and sacrificed every year in many cities. Each year the forest dept keeps vigil on trading of illegal body parts of owl at some suspected pockets.  

Two years back I was called upon by the forest dept to identify the body parts of different owls which they had seized from some traders. It was a pitiable scenario with so many owl parts (feathers /nails /beak etc) scattered on the table, all these owls must have been captured and killed for black magic.

Many of the owl species are facing population decline in Indore city.  While visiting the different areas of the city while preparing the list of birds found in Indore division for the forest, I noticed that the owl habitats are vanishing fast.

There are seven species of owl found in Indore city and its outskirts. 

1.Spotted Owl

2.Barn Owl

3.Rock Eagle Owl

4.Mottled Wood Owl

5.Jungle Owlet

6.Collared Scops Owl

7.Short eared owl

Spotted Owl: They are the one most easily spotted. Earlier I had used to see them regularly at 10 different locations in well wooded gardens and farmlands at city fringes, but slowly they got lost from all those places except one.

Barn Owl: This owl has a white face contrasting to its brown body parts.  At night it looks very fearsome. This owl is easily adaptable to the urban areas but now its count has also decreased.

Indian Eagle Owl: This species is the largest of owls found at the city outskirts.  Mostly it remains at the edges of the city, where he gets most of the food in the form of rodents.  It spends the day under the shelter of a bush or in some large foliaged tree near villages. 

Mottled wood Owl, Jungle Owlet and collared scops owl (seen above) are mostly found in forest areas. They are frequently seen in Kajligarh forest area under choral forest range.

Short eared owl is a winter migrant in our area and is regularly seen around Sirpurlake during winter months.

Owls being nocturnal, are not seen very easily in day time.  During  day time they just relax at their secluded places away from their hunting places.  Once spotted in day time by any bird they are fiercely chased and mobbed away by drongos and crows.  All of the owl species are protected  under the Wildlife (Protection) Act of 1972. They are included in schedule IV of the act.

However, the practice of capturing owls for various purposes is prevalent.  Each year, cases of owls seized from hunters and traders are reported from different areas.  Many people in the citystill sacrifice these birds, subscribing to the myth that the practice brings wealth.

The widespread use of these enchanting birds in black magic and sorcery driven by superstition, totems and taboos is one of the prime forces responsible for the decline of this group of birds. Owls have highest demand in the grey market.

Actually owl is a very beneficial bird for the farmers.  It consumes many rodents and protects the damage caused to the grains and plays a vital role in pest control.

( Text and photographs by Ajay Gadikar.  Ajay Gadikar is an  Ornithologist from Indore.) 

Understanding what gives rise to the patterns on the coats of rodents arise has moved a step closer, says S.Ananthanarayanan.

Indian epics and folklore say squirrels participated by carrying pebbles when Lord Rama built a bridge across the sea to Lanka. In appreciation, Lord Rama stroked them on the back, and hence the stripes that they carry since then. Evolutionary biologists, however, have sought an answer more in terms of the cellular, developmental and molecular processes that lead to the periodic appearance of hair pigmentation, even if it were Lord Rama who set those processes off, to start with.

Ricardo Mallarino, Corneliu Henegar, Mercedes Mirasierra, Marie Manceau, Carsten Schradin, Mario Vallejo, Slobodan Beronja, Gregory S. Barsh and Hopi E. Hoekstra, from Institutes in Harvard, Massachusetts, Stanford, Seattle, Madrid, Paris, Strasbourg and Johannesburg report in the journal, Nature, that they have identified the agent that causes differences in the action of pigment-creating cells, and hence the variations in the colouring of animal hair. This is a finding that could help understand how individual, visible forms of organisms evolve, the study says.

The genes that give rise to cells that produce melanin, a complex, chained molecule that gives skin and hair its colour, and the mechanisms that regulate the balance between dark and light pigmentation, are part of existing knowledge through research based on animals, like laboratory mice.  How these processes contribute to the array of pigment patterns seen in wild animals, however, is not understood, the study says. The researchers hence took up the naturally occurring coat pattern of the African striped mouse, to gain insight into the processes that bring about stripes, “a striking and characteristic pattern that has evolved independently” in a large number of animals, the study says.

While the melanocytes, or the cells that produce melanin, are present in many parts of the skin tissue, it is the presence of agents that allow the transport of specific parts of the genetic code to pigment creating centres that get the cells to become active. The study discovers that it is a protein called Alx3 that plays the role of regulator, by suppressing the action of Mitf, another protein that is implicated in pigment production by melanocytes.  The researches examined traces of these regulators, which are called transcription agents because they allow parts of the DNA to be copied as templates for the assembly of proteins, in the tissue of different parts of the animal body and where fur of different shades arose, and also at different times, starting from the early embryonic stages of growth, till adulthood.

 

A remarkable thing about the striped pattern that arises in animals is that similar patterns are seen in species which seem to have evolved along different genealogical lines. The last common ancestor of the mouse and the chipmunk, for instance, the paper says, dates back to 70 million years, or the time of the dinosaurs. While the African striped mouse has one light coloured stripe, sandwiched between two darker lines, on either side of its spine, the chipmunk and the squirrel display similar but distinct patterns.  Analysis of the proteins present in skin biopsies revealed that the colour distribution arose in the animals through similar pathways, of expression of the Alx3 gene and the Alx3 transcription agent, which regulates the rate of pigment production, and also the ASIP and Edn3 genes, which bring about changes in the pigments produced.

 

The discovery by the group writing in Nature is an advance in understanding the specific mechanics of the development of colours in a large class of animals.  The computer scientists-mathematician Alan Turing had developed a theory of how color or form-yielding agents, called morphogens, could spread  or diffuse at different speeds, and interfere, like light waves, to clump together or to negate each other, and create bands or spots of different colours.  Although without speaking of what the morphogens may be, Turing’s theory of ‘reaction and diffusion’ was able to explain the black and white patches on a breed of cows. The theory was carried forward by others and the stripes that appear on the back of the tiger are now understood as a pattern of pigmentation brought about by periodic waves of diffusion of chemicals in the tiger embryo.

There has also been some work to identify possible morphogens that lead to shapes, like ridges on the roof of the mouth of the common mouse, or the shape of some cacti. This approach is also used in modeling why some stripes are vertical while others maybe horizontal, or even the reason for organs, like the fingers, to grow in particular directions. The current work, on the African striped mouse, however, is the first time that the very agent that results in colour distribution has been identified. The reason why the variation in colours is in the form of  stripes, or even the different numbers of stripes is yet to be understood, but the action of Alx3 has now been identified and tracked down to the early embryonic stage when the spinal chord is just forming. 

An editorial in the journal, Nature says that the genes that affect the colour of the skin also affect other things. At the embryonic stage, the tissue from which the spinal chord is formed also spreads out and leads to the formation of the hair and skin, the bones of the face, the nerves in the intestines, parts of the heart and the adrenal glands, crucial parts of the sense organs and many body structures that are unique to vertebrates, the editorial says.  Unusual skin pigmentation is thus seen to signal other ailments. Deficiency in Alx3 leads to the spinal chord or brain not forming correctly, a condition that can be moderated by doses of folic acid and deficiency of which in human mothers leads to spinal chord defects in human babies, the editorial says. It is again mutations in the Alx3 gene that causes facial deformities and failure of the facial bones to knit properly. Understanding how the stripes come about on the backs of rodents is hence more than skin deep, the editorial says.

Chipmunks ETC

[the writer can be contacted at response@simplescience.in]