October 19, 2012

How old are trees in the Amazon?

We know this tree is tall- but how old?

How old are trees in the Amazon?
How can you tell the age with no tree rings?

Most people are familiar with the technique of looking at tree rings to measure the age of a tree. For every ring, you can see another year that the growth was stunted in the winter and flourished in the summer. However, that presents a problem for aging trees in the tropics where the seasons aren’t typically as well defined. 

So, how is it done?

There are a few ways it can be done, and by using a combination of techniques a solid estimate of the age is possible. Here are few of the most modern techniques:

Carbon Dating 
When plants change carbon dioxide into organic matter (i.e. when they grow) during photosynthsis, they have an amount of a molecule called carbon-14 that matches the atmosphere. After entering the plant, the carbon-14 declines predictably over time via radioactive decay into nitrogen-14. So, by measuring carbon-14 in the middle of a tree (the oldest, first year growth) you can then get a pretty good rough estimate of the age of the tree. The downside? It takes a long time to analyze the tree in the lab, and not all trees sequester carbon at the same rate.

Invisible Tree Rings
Recent research showed that some tropical trees that don’t appear to have tree rings actually do have them- they’re just not visible to the naked eye. However, by taking x-rays of them you can see the calcium rings, associated with yearly growth, and therefor determine the age. The downside? Researchers still aren’t sure how many trees share these calcium x-ray visible rings.

Normal Tree Rings
Tree rings visible on this tree in the Amazon.
It ends up that a lot more tropical trees have tree rings than originally thought. Here in Tambopata, for instance, the dry season is marked enough that tree rings would be visible in a lot of species.

How old are the trees? A good rough estimate is that it takes trees between 60-100 years to become mature, and can live for up to 600 years!

References from here, here, here, and here.

See more posts by biologist Phil Torres at TheRevScience

October 18, 2012

Amazon Camera Traps

We've had a camera trap set up at the Tambopata Research Center to catch glimpses of the elusive mammals in the area- check it out!

October 15, 2012

Extraordinary Beaks


Extraordinary Beaks
by Iva Petrovchich, Pandemonium Aviaries intern

One of PeruNature’s partner groups is Pandemonium Aviaries, a 501(c)3 non-profit bird sanctuary where exotic endangered birds are being kept and bred until they can be reintroduced to their native communities. Based in Silicon Valley and founded in 1996, Pandemonium Aviaries has helped upwards of 350 birds and continues to grow through both local and worldwide support. Among the numerous aviaries, there is a small population of macaws that dance, sing and play.

For those of us that started our relationships with birds tentatively and with the slightest tinge of fear accompanying the awe, noticing the beaks on macaws is an automatic first instinct. And why wouldn't we? They're something amazing. The most conservative estimate would have macaw beaks exerting a pressure of over 500 pounds per square inch, and they easily crush Brazil nuts. If that doesn't intrinsically reinforce being over cautious, nothing will.

There are a lot of uses for beaks that come quickly to mind, in addition to crushing Brazil nuts or lunging at an overeager acquaintance to assert their boundaries. Fighting, foraging, killing prey, feeding their young, using objects, luring potential mates-- things we have come to expect. But perhaps, we are missing a more delicate feature of beaks.

When comparing the native sparrows, finches, and Jays that visit Pandemonium Aviaries to the enormous-beaked birds that enamor visitors through Peru Nature, the idea that birds from warmer climates have larger beaks than those from colder climates is obvious. But why? What accounts for the huge beaks of the toucans, for example, that one can see when taking a trip with Peru Nature?

One reason for these beak sizes may be that toucans have shown the ability to regulate their temperatures with their beaks. Considering that birds already operate at a higher metabolic rate than mammals, keeping cool is a very important process and these thermal windows are critical. Luckily enough, toucan beaks are richly lined with blood vessels. By being able to modify the blood flow to their beaks, they can control how they will radiate body heat. When the toucans overheat, blood rushes to their beaks; when the weather is colder, they restrict the flow. In infrared pictures, you can see the toucan's beak light up like an incandescent bulb when they get warmer than their liking. In fact, regulating blood flow in their beaks can account for 30% to 60% of their body's total heat loss, and it is estimated that toucans can lose as much as four times its resting heat through their beaks.

While the beaks of tropical birds may register with us first and foremost for their power and strength, we must also recognize that they are even more complicated than we may have anticipated. And while the thermoregulation studies haven't quite panned through with macaws to the same extent as they have with toucans, I can't help but admire at the macaw smiles at Pandemonium Aviaries when they take a break from dancing.

Purple Pleasing Fungus Beetle


A purple pleasing fungus beetle, Gibbifer sp. - Phil Torres
If you stop to think about it, purple is one of the least common colors in all of nature, even here in the Tambopata rainforests. 

Thus, when I come across anything purple, from a leaf to a beetle, I always take the time to try and get a good shot.

One of the more pleasing-to-the-eye beetles around the Tambopata rainforests is this here Gibbifer sp., a pleasing fungus beetle. I’ve seen them range from light sky blue, to dark blue, to this purple, and I’m unsure if they make up one species or several.

Pleasing Fungus Beetles are beetles in the family Erotylidae and feed exclusively on basidiomycete fungus (aka shelf-mushroom looking fungus) as both larvae and adult, with specific host species they feed on. If you find a dry fallen tree with some fungus growing on it, you almost always will find one of these beetles shuffling around. Their bright colors make them quite conspicuous so they likely have some form of chemical defense.

So why are the colors purple and blue so rare in animals? Scientists actually aren't exactly sure. It likely has to do with the complexity and rarity of molecules that create the color blue/purple color, as well as the fact that those pigments that form blue/purple are found more in high saline alkaline environments. These alkaline environments are difficult for most organisms to thrive in, thus the low numbers of animals that actually can be blue/purple.

This could be why we see a lot of blue/purple color formed from a structural scattering of light (much like a blue morpho) rather than an actual pigment, because scattering is a bit 'easier' to evolve.

As for the beetles, I have no idea why they are called pleasing fungus beetles, perhaps because they really are pleasing to look at or their notably docile ‘personality.’ There is also another family, the Endomychidae, which are commonly called the ‘handsome fungus beetles.’ I think someone was fond of fungus beetles.

For a great review and key to genera of the family Erotylidae, see here.

And for the final test, say “purple pleasing fungus beetle” five times fast.

To see more posts by biologist Phil Torres, check out TheRevScience.com

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October 12, 2012

The Froggy Medicine Factory


The monkey frogs of the Tambopata rainforest are literally covered in medical secrets yet to be discovered.

I think we caught this monkey frog on a bad day.
Maybe she'd cheer up if she knew she could save lives.

What makes monkey frogs remarkeable is their incredible array of chemicals that exist on the slim that covers their skin- as of 2009, there were over 200 unique peptides discovered in that goo. These chemicals likely evolved to provide them with protection from predators, illnesses, and drying out, however a multitude of them have proven to have a lot of potentially useful purposes for humans, too.

The monkey frogs, tree frogs of the genus Phyllomedusa, are made up of about a dozen species here in southern Peru. They are called monkey frogs because they tend to crawl along a branch like a monkey, rather than hop like a frog.

New peptides are being found all the time on these frogs, and with a variety of functions. Take, for instance, the frog Phyllomedusa bicolor, the giant monkey frog. One study looked at its use by the indigenous in the Amazon. They found that placing the frog on burnt skin causes an "increase in physical strength, heightening of senses, resistance to hunger and thirst, exalted capacity to face stress situations." The drug component that causes that even remarkably makes up 7% of the frog's weight! 

Forget spiderman, I think frogman is more likely to fight crime.

Not just to become a superfrog-like.

Amplectant Phyllomedusa camba.
There are a multitude of other studies on their antimicrobial properties, here and here are good examples, and in 2012 alone I found 56 studies with the terms "Phyllomedusa skin" and "drug" included, so it is an very active area of biomedical research.

As far as I know, the compounds are all still in testing phase and not yet used by humans for medical purposes. However, they doesn't mean humans haven't found a use for them, legal or not- one monkey frog caused a scandal because it was being used to dope up race horses, making them both excited and numb.

So, while we can look forward to seeing what interesting and useful compounds come out next, please don't take this as an excuse to try using a monkey frog drug recreationally- the compounds are poisons, afterall, and we don't yet know the long term effects or short term risks. It really is extremely dangerous.

I do know one person who 'doped up' on an unknown monkey frog and claims he felt he was dying then thought he turned into a frog. For all we know that frog condition could be a permanent one, so don't do it!

October 10, 2012

Ants, Plants, and Bodyguards


Here in the rainforests of Tambopata, we see many interesting relationships between different organisms. Some are just smaller than others.

Camponotus femoratus ant feeding on an Inga extrafloral nectary.
The plant provides the sugar, the ant provides the protection.
Photo by Phil Torres
If you think about it, nectar is typically pollinator bait- it draws insects like butterflies, beetles, and flies into the flower to drink, covering them in pollen, and helping the plant reproduce. However, pollination is not the only role that insects can play for plants- they can also be protectors.

What you are glimpsing above is an ant drinking out of an extra-floral nectary (EFN). An EFN is a fancy term for a source of nectar that lies outside the flower. These EFNs are typically located near the base of a leaf, or along an outer branch. Thus, any ant aiming to drink from it has to walk all the way up the entirety of the plant.

So why have an EFN? Over millions of years, a relationship can form between these ants and plants: the plants provide the nectar, and the ants provide protection. This nectar is even ant-diet specific, containing more sugar, and less amino acids, so they can have the energy to take down any herbivore that happens to attempt to feed on this plant.

The image shows an Inga sp. plant, however other plants can have relationships with ants that are even more complex than this. Some plants provide homes for them, some ants tend honeydew producing aphid 'cattle' on the plants, and some plants even reabsorb and 'eat' the anta' feces!

The ant in the image is only 3mm long. The well it is drinking out of, only about 1mm wide. Size clearly doesn't matter when it comes to interesting behavior.

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