Friday, December 30, 2011

transpiration inspiration

First off, let me acknowledge that I am a useless bum and have not posted in a timely nor consistent manner. I'll work on that...

Secondly, I hope everyone's holidays were filled with warm feelings, minimal family drama, and safe travels.

Now that that's out of the way, it's story time...

My dad’s dad, officially known as “Gramps,” always ends up bringing up a curious topic whenever I visit. I think that its elegance must deeply move him. We’ll be walking outside and encounter the same old, massive pecan tree in the yard. He approaches it and places a hand on it. “I would like to find one person who can tell me exactly how this tree can move hundreds of gallons of water from the ground all the way to its top every day.” I want to exclaim “Transpiration! Adhesion! Cohesion! Evaporation!” But I don’t.

Sir David Attenborough puts transpiration in a well-framed perspective. Take 3 minutes and 1 second to watch this clip:

Let’s talk about the components of this process; there are only two. Adhesion is the tendency of water molecules to stick to things. When you wash your hands, you must also dry them. The water clings to your hand until you forcibly remove it. This is adhesion. Cohesion is the tendency of water molecules to stick to each other. Like when you pour some water on a table. It doesn’t just scatter in a mist. It pools together as much as it reasonably can. This is cohesion.

Within trees and all vascular plants, a complex network of plumbing exists. One set of pipes is called xylem. There are tons of them. And these are some tiny-ass pipes. As in only one molecule of water wide. Huh. Then how can the trees get enough water to their leaves if their pipes are so tiny? The question should be how could they do it if they weren’t so tiny.

This is where adhesion comes in. Water is better able to cling to a surface with which it has maximal contact- which the tininess of these vessels provides. Now cohesion comes in. Where one molecule of water is clinging to the walls of xylem (adhesion), another is sure to follow and cling to it (cohesion) AND the walls of the xylem also (adhesion again). And behind that water molecule, another. And so on and so on. A long column of water forms within the xylem, under a tenuous tension that will collapse should it be broken at any single spot.

Let’s put this set-up in motion. Water evaporates from the surface of the leaves (via radiation from the sun or low humidity in the atmosphere), and our columns of water begin to move upward, the water molecules chasing their evaporating comrades. At the base of the tree, water molecules are sucked from the soil into the xylem, beginning their own journey to the pores of the leaves, soon to float away into a whole new world in the form of humidity. It is so simple yet so efficient- just like a straw. It is transpiration.

Gramps is still looking at me, wide-eyed and with one hand still on the pecan tree. I know that in reality, this tree is living proof of a divine creator for him. So I do not begin the whole adhesion, cohesion routine. Instead, I reply with the same affirmation every time.

“It really is something, Gramps. It really is.”

I think that satisfies us both.

Monday, December 19, 2011

lumpers and splitters

The number one question my college professors asked in class was “what is a species?” The predictable kids would shoot up their hands and explain that a species is a group of like organisms that can breed and produce viable, fertile offspring. And that is really not a bad answer. But there is no easy answer to this question.

I struggled for a long time to accept Linnaean taxonomy. That is- this system we have put in place to give animals Latin names to separate and organize them as much as humanly possible. We need it, for sure. It helps us organize evolutionary trees and distinguish one animal from another. But all of life is really on a grand continuum, and to me it almost seemed an insult to its complexity to try and finitely categorize all of its marvels.

After a few semesters of classes, I began to really get sick of how many species I was memorizing. But my feelings turned downright bitter when subspecies came into the picture. You’ve got to be kidding me, right? Can’t our scientific energy be directed to something more important?

I learned that those dirty scientists who insist on splitting groups of animals until there are at least a million species and subspecies per genus are called “splitters.” Those rational biologists who would like to clean up our present taxonomy by combining extremely similar animals are called “lumpers.” Until spring semester of senior year, I was a proud and unbudging lumper.

One of my best teachers of all time, Dr. Hill, devoted a class to talking about lumpers and splitters. He described to us what I just described to you. Someone raised their hand and asked whether he was a lumper or a splitter. After a brief pause, he said three horrible words. “I’m a splitter.” What? But I liked him. I liked a splitter? Gross.

Skip to the end of the lecture, and I don’t think it’s so gross anymore. As a bird biologist, he was acutely aware of the plummeting numbers of migratory songbirds. The more species of birds we have, the more birds the government can list as federally protected. Ahh. It was not an issue of organization at all. It was political. So much of science is driven by legislative politics. How had I never thought of it that way?

There’s something to be said for changing your mind. If it helps protect the birdies, I say to hell with a clean evolutionary tree. Split, people, split!

What do you think?

Monday, December 12, 2011

human to hope

Last year, I committed one of the deadly sins of scientific method. I said “I hope” in place of “I hypothesize.”

Let me set the stage. I am but a mere undergraduate, frightened and nervous to be presenting a research plan to a lab full of esteemed PhD and masters degree holders.  The lab meeting has gone surprisingly well- they have asked a lot of pointed questions, and none of them stumped me. After an hour or so of discussion, I’m feeling pretty confident and start speaking a little more freely. And then I say it…

“I hope to find significant variation within….”

I stop mid-sentence. I glance from face to face, slowly realizing what I had just done.

“I mean I hypothesize that I will find significant variation. I hypothesize. “

The damage had been done. The cardinal rule of scientific investigation: Experimenters must remain unbiased in order to obtain valid results. I know this; it has been drilled into my head relentlessly. What was I thinking?

After reflecting on my slip-up for the rest of the day, I realized that I knew exactly what I was thinking when I used the dreaded phrase. I was thinking how COOL it would be if I found that two salamanders species had evolved divergently so they didn’t compete with each other for food. That is remarkable. Somehow, the phrase “I hypothesize” just didn’t convey how cool this research question is.

I fully appreciate the necessity of indifference in scientific investigations. But come on people; it’s human to hope. Just don’t say it out loud- especially at a lab meeting.

Friday, December 2, 2011

coffee drinkers, this one goes out to you

Do you drink coffee? I myself am not so much a big coffee drinker, but I know lots of people are. If you consume even one cup of coffee a week, there is an indirect but very real way that you can help save wildlife. Please read on.

Songbirds (aka Passerines) are some of the most beloved animals we have in North America. They’re easy to find- look out of your window right now and I bet you’ll see at least one. Their songs make up the calming soundscapes of nature that people seek when they spend time outside. They’re oftentimes very beautiful. Here are some of my favorites-

Painted Bunting

Indigo Bunting

Black and White Warbler

There’s a whole subculture of birding enthusiasts across the country- it’s totally a thing. You’ll see them wandering around with binoculars, thousands of dollars worth of scopes and other optical equipment, and their trusty field guides in their packs. They will also likely have with them their “lifelist”- a list of all the birds of the continent with a little checkbox next to each bird for when said birder sees it. The satisfaction a birder feels when he or she checks a bird off his or her lifelist is comparable to seeing your favorite band play your favorite song live. Or eating a whole pan of brownies. Or whatever you find to be equally as gratifying.

One thing about many of the Passerines that makes them such a spectacle is their migratory habitats. Not all Passerines migrate, but many do. They head south in the fall to find food. Here in Alabama, the flocks of Cedar Waxwings are some of my favorites to look for in the winter. They come down from Canada for the winter and their soft wheezy calls make me think of cold winter mornings.

Cedar Waxwing

Many Passerines take it a step further and fly across the Gulf all the way to Central or South America. Here, they find shelter and food in the vast expanses of forests the tropics have to offer. For whatever reason, they especially like to roost in the trees of the large coffee plantations that stretch for miles and miles. The trees provide just the right amount of shade for the little coffee plants to be maximally productive, and apparently are just right for the migratory birdies too. A study done by the Smithsonian Migratory Bird Center found that shade-grown coffee plantations support a greater amount of migrant species than other lands devoted to agriculture. Win-win, right? Migrant birds habitat is protected and the coffee growers have good harvests that help to fuel their country’s struggling economy.

It was a win-win until recently. Coffee growers have started to plant another species of coffee plant that does not require the shade from trees overhead. Without the need for trees overhead to provide shade, planters mow down huge tracts of land to plant a greater amount of coffee. Problem is, migrant birds are still migrating… but to what? Their winter homes are disappearing. And consequently, so are they. Fast. So fast that your kids may not see but a fraction of the songbird diversity that you grew up with.

But can we really hate on the Central and South American coffee planters? I say no. They and their economies need the money, and the difference in profit between planting shade and sun coffee is huge. They’re doing what they must to support their families and economies. 

This is where we come in. As one of the largest consumers of Central and South American-grown coffee, America has the power to decrease the demand for sun coffee and increase the demand for shade coffee. And thanks to the Smithsonian Migratory Bird Center, it is easy. Next time you shop for coffee, look for this seal.

If the package bears this image, it means that the coffee inside has been grown and harvested from a certified shade coffee plantation. If you can’t find it at a local grocer, I encourage you to purchase your coffee online.

By making this small change, hundreds of species can be saved. Drink bird friendly coffee, save biodiversity!

I hope you will research this issue further. Google it up, folks. This is important.