Wednesday, January 30, 2008

Solastalgia: olacium (comfort) and algia (pain)

IISc lost the hovering diving pied kingfisher because water bodies disappeared a while back, one among many others
I don't usually link articles but this one written by Clive Thompson on Glenn Albrecht's work is irresistable. An excerpt:

"... scores of Australians described their deep, wrenching sense of loss as they watch the landscape around them change. Familiar plants don't grow any more. Gardens won't take. Birds are gone. "They no longer feel like they know the place they've lived for decades," he says.
They're suffering symptoms eerily similar to those of indigenous populations that are forcibly removed from their traditional homelands. But nobody is being relocated; they haven't moved anywhere. It's just that the familiar markers of their area, the physical and sensory signals that define home, are vanishing. Their environment is moving away from them, and they miss it terribly."

Monday, January 28, 2008

Seperating the men from the boys: variance

Short nosed fruit bats in a mating group

Get ready for a lot of speculation. I've blogged about the harems of these bat's before. This post is just to give you a feel for what variance is like (and to show you the pictures) . I looked under the eaves of the Physics and IPC departments. I found a total of three harems, the top male, in the photograph above monopolised 10 females. (Based on a bat guy's know-how I'm guessing the bat on the outside is a male, the ones in the group are all females. You do see a few hints of dimorphism between the two.) The second largest harem had 7 females, and the smallest, in the next photograph had 3. There were three pairs and four loners.

The smallest harem

If my conjecture is right, (and seeing how it skews the sex ratio quite strongly towards females it may not be), then three males between them managed to have primary sexual access to about 90 percent of the female population (20 of 23)!

Biologists like to call this reproductive skew, the notion that reproductive success is spread across a population in a skewed manner, allowing a few individuals to produce the most offspring. On average each male should have 2.3 females, paired up with him here (23 females, 10 males). But some males have nearly 5 times that number and others have none!

A pair (Can you see the differences between them? My guess, right side one's a male)

There are much wilder skews in reproduction in other animals, think about social insects. Honeybees, for instance, in which the queen bee is the sole reproducing female among thousands and thousands of sterile female bees. Biologists have used kin selection theory to explain such behaviour, where some animals willing give up mating rights to help kin, because they receive sufficient indirect genetic benefits through them to make up their losses.

A solo roosting bat

In many other systems, however, such as this and other polygamy systems, this won't work. The relatedness between these females is likely to be low. So what's going on? Reproductive skew theory is a system of models that attempt to add ecological and social factors to kin selection kind of ideas within some kind of formal quantitative frame-work. In this system, among the bats, the key driver appears to be access to a resource that makes all the difference, a roost. The difference between boom and bust.

Anecdotally, two things. The largest harems in IISc have always been in the same roost. So there seems to be something to that idea, good roost, high attractiveness . Also, as you would have noticed I shot these images using flashes. Now the bright lights in the roost were not appreciated and were probably stressful and disturbing. Now these bats can fly in the day, they just don't from fear of predation. There I was however, simulating it to an extent.

But none of the animals in the harem situation moved, neither did the pairs. The only bat that instantly took off and moved to another roost was the solo bat. The picture above is him taking off. I suppose one could read something interesting into it, the roost may not have been so good and so the male lost little in moving on. The other males, with the harems, however, stood to loose both females and the roost and well the hung on for all their fear and tribulations. For which I'm grateful, off course!

Bat huddle or exchanging parasites

PS: I did warn you this was going to be speculative.

Thursday, January 24, 2008

Aphids: speedsters

Ants tending their aphids
Aphids are perhaps most famous for being the poster children of mutualism. To be able to cooperate with another species is quite an achievement. Particularly in the eyes of humans, a species whose own history of cooperation is extremely checkered. Then to stably maintain that cooperation over evolutionary time-scales where we fail often, even over the shorter course of human history. But then the clock ticks over slowly at the level of genetic evolution. Meme time is a faster beast.

Another ant, probably not another aphid
Apart from being cattle to their social arthropod herders, aphids are interesting in other ways. Ways that relate again to time, ecological time. Ways that relate to the rhythms of days, months and years. Aphids feed on plant sap. They used specialized mouth parts to dig into the living phloem of plants to extract sugar and other nutrients from the plant. They are, in a way, plant parasites. Gardeners will differ with my dilly-dallying and pull out the aggressive pesticides.

Aphids feeding on bamboo (click on image to enlarge)
Many species are monophagous, they can eat only a single species. In the dispersal stage they find the plants they eat using chemical cues. They can probably infest a plant only at certain stages in it's life cycle and must find plants that are appropriate to them. Such resources are often rare, ephemeral and short-lived. To make the most of the possibly short-lived windfall, these insects must expand rapidly in number.

Aphids speed up reproduction time in a truly spectacular way. They reproduce parthenogenetically. No mating. They can mate and do under certain circumstances, but they can switch to just making perfect copies of themselves. You might ask ok, but just how much time does an aphid shave off by skipping the finding-a-mate stage? Admittedly only a little.

The truly large time saving comes from a crazy trick called the telescoping of generations. Female aphids give birth to parthenogenetically produced female aphids who are already pregnant with the next generation. That amounts to a larger reduction of reproduction time. And it's what allows them to infest a plant in your garden in the short span of a few days. It's also what might allow them to develop quick resistance to the pesticides gardeners and farmers use. A granddaughter and daughter is exposed to everything a female aphid is exposed to and selective pressures needn't work independently on each generation, which I think should speed up the process of developing resistance.

A ladybird feeds on bamboo aphids

Off course, such abundance does not go unnoticed in the competitive world out there. Aphids have their predators, ladybirds most notable of all, lacewing larvae, hoverfly, wasps and many other tiny carnivores. Many of these predators are believed to be attracted by plants, who produce volatile chemical cues in response to aphid attack. All these wonderful weapons deployed in a war for survival in a system in which the upper hand probably changes often and in innovative ways.

Wednesday, January 23, 2008

Flame of the forest

I'm terribly sorry I haven't really been posting much, there's been a lot to do. With some luck we should be back on schedule shortly.
These trees are blooming all over right now, so I thought it was a good time to resurrect the post.

Flame of the forest

This tree deserves it's name in more ways than one. The flowers look like flames individually. A tree in flower does really look like it's on fire. And every bird within a mile's radius is in love with it. And off course squirrels and insects.

Two days of waiting paid off! Ta dah here they go. The last one, a Spangled drongo, is a western ghats species. If you look at its distribution in the GI and I its painted along the western ghats. Well, it's here and it picked this tree to feast upon.

Flame of the forest
You know sometimes I feel like one of those sad homeless people you see on the streets, clutching at their treasures. Things no one else would find even remotely interesting. I'll be raving about some bird no ones even ever heard of before. Well, fortunately there are a few people who are a bit like that in CES and I'm not considered stark raving, but only moderately mad. Well, the slightly deranged vocabulary that apparently accompanies this enterprise does make up!

Wednesday, January 09, 2008

Don't fear the shadows

Wildlife photographers, particularly macro photographers, do not like shadows. They'd prefer it if their images didn't have any. Much of their obsession over lighting is about removing shadows or at least about softening them considerably. Diffuse light which does this is everyones manna from heaven.

Painted stork in shadow on a roof in Kokkre Bellur

There's a simple reason for this dislike. Shadows typically obscure details and features. Parts of an image in shadow usually do not show great detail. You'll hear talk now and then of good shadow detail but that's a relative thing. In comparison to the middle tones in an image, you're not going to see much in the darker (in shadow) regions. (Take a look at the two painted stork images, take one after the other.) And somehow, somewhere along the line, detail has become the be-all and end-all of wildlife photographers. Or at least the majority of them. This universe is slowly changing now. But this change is not the only reason one ought to embrace shadows.

The stork steps out of the shadow

Wasp nest surface front diffuse lit
Shadows are important to limning form. They are darn important. Take a look at the preceding and following photograph. They are of the exact same object, same view and position, no change except the direction and hardness of the light. In the second image, the light comes in from the right hand, causing the bumps on the surface to throw shadows onto the ares under them. The valleys elongate and change the shapes of the shadows giving you a sense of their shape and the curves of that surface. You suddenly have a sense of the shapes of each of those bumps and valleys.

Wasp nest surface side hard lit

The visual areas of our brains have wired into them algorithms that allow us to infer shape from what is essentially a 2D representation of the world, that the retinas pass onto them. There are two pieces of information that the brain uses to reconstruct shape in the brain. One piece of info comes from the stereoscopic nature of our eyes, two 2D representations from two eyes set at a fixed angle can be used to reconstruct shape. This is missing in a photograph which is truly 2D. Viewing a photograph is like viewing the world with a single eye.

The other info that can be used are shadows (and hence, off course, bright areas). Objects cast shadows depending on their shapes and on the surface which the shadow is cast. The shape can can often be inferred from the shadow. Whether we are hardwired to do this or learn I don't know, and am too lazy right now to find out, but we can. The shapes of uniformly lit and hence even toned objects like the wasp nest surface in the 1st wasp nest photograph cannot be apprehended at all. We take our cues from the smallest hints, we do it so effortlessly that it does not occur to us that we couldn't without shadows.

Giant african land snails with a smaller native (?) snail
Note the shadows at the far end of each whorl that shows the curve of the shell within the whorl

Note that the lack of shadows makes the shape of the snake in section hard to apprehend, makes it look flattened

Now think of shadows at a smaller scale. They create texture. Rather they limn texture. Something that is completely missing from the first wasp nest image and predominates in the second. For what is texture, but many shapes at micro scales.

Red weaver ant. The leaf texture shows up because of shadows

Off course none of these are good reasons not to use shadows on their own merit, as excellent design elements.

Leaf shadows
Katydid hide and seek

Wednesday, January 02, 2008

Kaadupapa: forest baby

Slender loris on branch
I find it a little hard to decide precisely which attribute earns the Slender loris it's Kannada name, Kaadupapa. Whether it's the childlike huge eyes, adapted for nocturnal vision. Or the tiny tiny hands, equipped with pads, for a grip that does not often fail. The fragile slender limbs, the slow deliberate response to everything. Or the whistle, a territorial call, which could be mistaken for a child's demands for food.

Slender loris on branch

All the furry, feathery creatures of the world find their way to our doorstep. CES is the orphan-house for animals. We have had beautiful bats hung on our doorway, with a note in a childish hand weighed down with stones on the doorstep left as explanation. People regularly bring us squirrel babies, naked, still blind to the world. The common denominator among these many is that they shiver, they are cold. Small animals (all that remains in this truncated land loose heat rapidly, they are more surface than substance and this is their undoing. The first Loris we ever caught was retrieved from the bicycle repair shop in a rain-storm. It had an arm missing, one hopes it was a predator, a non human one that took it. This one came to us late yesterday night, few details reached me through the many layers that were between the finders and the 'rescuers'.

Slender loris close up

Most of the time, when there are no apparent injuries, we surmise that these little ones are just cold. All they need is a little warmth and food and they are ready for the world again. We transferred this little guy to a spacier box, gave him a towel to keep warm with and a few crickets to feast on and wished him beddy bye for the night. The lab is warmer than the outside and that should help. The warmth, rest and food seemed to have done it well and it was reasonably active in the morning. A little checking showed no obvious injuries or broken bones (with gloves, these guys know how to bite real good). So we figured it's best to let it go.

Not everyone is so lucky. The last one we had was all skin and bones and breathed his last before my eyes. I slept not so much last night, hoping this guy would not go the same way. Or escape and wander around the lab like the first one did.

Lorises are well protected by law in India. But their nocturnal nature has spawned myths and rumors about them, the ghost like call does not help their PR one bit. And like everything else on this earth, they are threatened by habitat loss. The IUCN includes it in the Red list and terms it near threatened. It's probably the most exotic animal IISc hosts, also one that claims kinship to us, a primate. According to a Sindhu, a Loris researcher working at NIAS, we have a healthy population here which can, given a chance, last a while. Here's hoping IISc doesn't loose a Red-lister in it's quick and dirty march towards what (everyone hopes) is (at least) an (infrastructural) A-list.

Large eyes help in nocturnal hunting

Wishing you a great 2008!

My present for 2008, a slender loris