Oh, Deer: How Do Aspen Trees Survive Herbivory?

A White-tailed deer browsing in Duluth, Minnesota (Photo: DPR, 2012)

Because of their relative immobility, plants are often perceived as being largely defenseless against predators. This couldn't be further from the truth. Anyone who's watched Journey to the Center of the Earth or Jumanji has seen exaggerated fictional depictions of such plants as the Venus Flytrap or the Pitcher plant. But even these striking examples miss the more common, albeit much more subtle, mechanisms of plant defense. The goal of my graduate research over the next couple of years is to elucidate the joint costs and benefits, as well as the ecological implications of what we believe to be a multivariate defense system in aspen trees towards mammalian herbivores. Specifically, I will be examining how Quaking aspen trees (Populus tremuloides) balance three defense traits (resistance, tolerance, and escape) to survive herbivory by White-tailed deer (Odocoileus virginianus) at various stages in their life cycle. If they spoke English, I'm sure the deer would tell you that plants do, indeed, have active defense systems. Although, if you've ever gotten tangled in poison ivy, you should already know this!

Sea Urchins: The Marine Hedgehogs

Red Sea Urchins in a kelp forest off the coast of British Columbia  (Photo credit: NatGeo)

The sea urchin is a small echinoderm found in marine ecosystems from the very depths of the ocean to the intertidal zone. Feeding primarily on algae and small invertebrates, these spectacular pin-cushions move along the ocean floor using tubular feet powered by a water vasculature system. In 14th century England, the term "urchin" was used to refer to the hedgehog. Thus, when these spiky marine creatures were first described, they were given the name "sea urchin." From kina in New Zealand, to uni in Japan, sea urchin is served in local cuisine all around the world. But perhaps more importantly, this organism has helped better our understanding of animal embryonic development. A dioecious organism, the male and female urchins produce sperm and eggs, respectively. Both gametes are dispersed into the open ocean in synchrony, in order to increase the likelihood of fertilization.

In a recent laboratory exercise, I had the opportunity to collect gametes from live sea urchins of the species Lytechinus variegatus. After observing the sperm and eggs under a microscope, we mixed the two and watched as the eggs were fertilized, began to cleave, and eventually gave rise to motile, feeding plutei. The video below, of a 48 hour pluteus was created by taking a series of images through the larva on Rhode Island College's new Olympus FluoView 1000 confocal laser scanning microscope. The green coloration is the result of autofluorescence.

Thanks to Dr. Thomas Meedel of Rhode Island College for the excellent lab, and Dr. Eric Roberts for his assistance with the confocal microscopy. 

The Namib Desert Beetle: A Recipe for Water

The Namib Desert Beetle laden with water droplets (Photo credit: Solvin Zankl)

As the early morning fog drifts across the Namib Desert of south-west Africa, an army of spindly-legged beetles emerges from the sand. Accustomed to an average annual rainfall of one inch, these critters are eager to employ their water collection apparatus that makes them so unique. The process begins when heat is radiated from the matte black exoskeleton, resulting in a body temperature slightly lower than that of the surrounding air. With the beetle's body held at a 45° angle to the sand, the moist breeze contacts the cool exoskeleton and water condenses into small droplets. This beading effect is facilitated by a series of hydrophilic (water attracting) bumps surrounding by a waxy, hydrophobic (water repelling) surface on the insect's back. The droplets may grow to nearly a quarter of an inch, and then roll down to be gratefully sequestered by the beetle's mouthparts. And then it's back down the dunes and away from the morning sun for these diminutive hydroplants.

A seawater greenhouse in Australia (Read about the exciting initiative here)

Researchers at MIT have used this peculiar water collection mechanism as a model for the synthesis of materials used in a range of innovative research and industrial devices (See the news article here). Among other applications of this mechanism is a seawater greenhouse project designed for arid coastal regions, described by Michael Pawlyn in his presentation entitled "Using nature's genius in architecture" (Available on TED here). These projects represent yet another example of innovation based directly on natural systems observed on this planet - the ultimate design project.

Can't get enough?
The beetle's water collection mechanism was first described in the article: Parker, Andrew R., and Lawrence, Chris R. November, 2010 "Water capture by a desert beetle." Nature 414: 33-34. More about this insect, and other biomimicry projects can be explored on AskNature. Watch the BBC wildlife feature on this beetle here.

I'm Taking a Lichen to This.

A colorful array of cructose lichens (Photo credit: Arizona-Sonora Desert Museum)

That crusty patch of plant-like material growing on a rock behind your house is called a lichen. But it is also so much more. Lichens are composite organisms formed by the association of a fungus (the mycobiont) and an alga and/or cyanobacterium (the photobiont). Together, they form an organism with physiological properties quite unlike that of either of the equivalent free-living constituents. For one, lichens are surprisingly tolerant to a range of environmental parameters, allowing them to live in some of the most extreme conditions on the planet. And yet, they serve as “canaries in a coal mine” when it comes to pollution, due to their sensitivity to many environmental contaminants. The unique symbiotic relationship exhibited in lichens reveals itself in a variety of shapes and sizes, including hair-like (filamentous), crust-like (crustose), leaf-like (foliose), and powder-like (leprose), among others. The photobiont provides sugars produced by the reduction of carbon dioxide using sunlight, while the mycobiont provides nutrients and a hydrous environment for the bacteria or algae. Apart, many of the companion organisms cannot survive. Food for thought: How does one classify a symbiotic organism made up of a fungus and an alga and/or bacterium?

Film Feature: 180° South (2010)

Surfing below Cerro Corcovado, Patagonia, Chile (Photo credit: surfriderhumboldt)

The iconic stone statues of Easter Island serve as an object lesson in conservation when you hear the backstory of the rise and fall of an entire culture, and environment. What was to be gained by erecting such extraordinary effigies? And at what price? On his quest to follow the monumental 1960's journey of Yvon Chouinard and Doug Tompkins, surfer and rock-climber Jeff Johnson learns several important lessons in conservation along the way. From landscape-transforming dams in South America, to video gaming habits in the United States, there is a need to step back and rethink our ecological impact on the planet. An incredible story of ordinary people taking part in the conservation of some of the most beautiful habitats on earth, this film threatens to inspire you to do the same.

Find the official film site here, or purchase on Amazon here. 

Film Feature: The Botany of Desire (2009)

The four feature crops of The Botany of Desire (Photo credit: HomesteadGardens)

In this film, based on Michael Pollan's 2001 national bestseller The Botany of Desire, the symbiotic relationship between humans and agriculturally-significant plants is explored via four representative crops. The apple, prized for its sweetness, the tulip for its beauty, cannabis for its pleasurable intoxication, and the potato for its power over human fate. By considering the history of these four plants, from their humble origins in the wild to their modern-day place in human economy and society, the film approaches the association from a plant's perspective to ask the question: do plants "use" humans as much as we use them?

The apple is thought to have originated in Kazakhstan, and later introduced to the rest of Asia, Europe, and eventually America, where Johnny "Appleseed" Chapman played a major role in spurring the adaptation of robust apples varieties to the New World by planting seeds rather than grafting selectively-bred species onto rootstock. Today, scientists and farmers are responding to pest and disease threats to monocultured apples by harnessing the biodiversity of "old world" breeds through cross-fertilization, gene transfer, and mixed crops.

The history of the tulip is perhaps even more astonishing. From its original distribution in central Asia, the obsession over the flower's beauty blossomed to result in the "tulip mania" of 17th century Holland, where a single tulip bulb sold for more than the grandest canal house in Amsterdam (in today's economy, equivalent to a town house on 5th Ave, or 10-15 million dollars). Although this absurd speculative bubble crashed in 1637, the obsession exists even today - with no better illustration than the Dutch Aalsmeer Flower Auction, which covers an area greater than 200 football fields and processes 19 million fresh flowers a day (roughly 30% of the world's flower market).

Few plants have had such an influence on human society as Cannabis, or marijuana. In America alone, 750,000 arrests are made per year for possession of the plant or drug, accounting for one third of all crimes. An estimated 15 million Americans use the drug on a monthly basis. Cannabis was discovered in India and China thousands of years ago, and has since spread to almost every country where suitable climates can be accessed or simulated. Scientists in Israel have recently found that THC, the compound responsible for the plant's hallucinogenic effects, acts similarly to the brain's own molecule, anandamide - involved with the calculated "forgetting" of extraneous sensory information. Do you really need to remember every face you saw at the transit mall this morning? This connection, according to some, offers potential uses of Cannabis, or THC, in the treatment of posttraumatic stress.

And last, but not least, is the potato. Unlike the previous examples, this plant originated in the Andes range of South America before introduction to Europe in the late 16th century by Spanish conquistadors. It very quickly became the staple food source of Northern Europe, especially Ireland - facilitating the Industrial Revolution and resulting in the death of 1 million people during the potato famine of 1845. Though the Great Famine should have served as a lesson, the agricultural sector continues to practice monoculture of this crop - churning out enough Russet Burbank potatoes to provide the 7.5 million pounds of French fries eaten by Americans every year. Recent efforts have been made to integrate polyculture practices, natural pests, and genetic engineering into the potato industry to save environmental, health, and economic costs.

The take-home message? Humans are intricately woven into the web of life, with plants impacting our lives just as much as we impact the plants' lives. In order for this mutual relationship to continue and thrive, we must allow the plants to adapt just as we do ourselves, and part of that means eliminating the pervasive practices of monoculture and pesticide.

Find the PBS site on this documentary here. 

Photo credits: Apples (ImageShack), tulips (vo2ov), cannabis (Susty), and potatoes (Guardian).