Madagascar’s Upside-Down Trees

(Photo credit: Gil.K/Shutterstock)

Madagascar is home to six of the world’s eight species of baobab trees. (Photo credit: Gil.K/Shutterstock)

The baobab is a tree with an unusual look. Many compare its appearance to a tree planted upside-down, as it looks like its roots are reaching toward the sky. [Read more…]

Australia’s Pickiest Eater

koala

Koalas, one of nature’s pickiest eaters, choose to only dine on eucalyptus leaves. (Photo credit: Purestock/Getty Images)

Many people have favorite foods. But the koala takes “favorite food” to the extreme. These Australian marsupials have evolved to live almost exclusively on eucalyptus leaves. And if that isn’t picky enough, recent research suggests that koalas are highly selective as to the species of eucalyptus they prefer and even the individual trees from which they choose to eat. How have these animals become so picky, and how can scientists use this information to aid in koala conservation efforts?

Filling a Niche

In ecological terms, the highly-selective diet of the koala makes them a specialist, that is, a consumer that primarily eats one specific organism or a very small number of organisms. Specialist species are generally sensitive to environmental changes, especially changes that affect the availability of their food source. However, the pickiness of koalas is likely an evolutionary adaptation.

Eucalyptus trees are the dominant trees of Australia. In fact, there are more than 700 species in the genus Eucalyptus, and most are native to Australia. However, the leaves of these trees are actually very low in protein, not easily digested, and contain compounds that are toxic to most species. Therefore, the ability for koalas to specialize in eating eucalyptus leaves has allowed them to fill an ecological niche. Koalas have virtually no competition for their preferred food source.

Koalas spend approximately 18-20 hours each day sleeping, and most of the remaining time is spent eating. They eat about 500 grams of eucalyptus leaves each day. A number of adaptations allow koalas to digest this food efficiently:

  • Powerful jaws allow the koala to chew the leaves into a very fine paste.
  • The koala’s liver is able to deactivate the toxic compounds found in eucalyptus leaves.
  • A portion of the koala’s large intestine is greatly enlarged to maximize the amount of nutrients extracted.

Studying Feeding Preference

Recent research has focused on finding what characteristics of eucalyptus leaves make them tasty for koalas. In one study, scientists tested a variety of leaves on captive koalas and recorded how much they ate. By analyzing the chemical composition of the leaves that koalas preferred, these scientists found that koalas ate less when the leaves provided to them were high in certain chemicals called formylated phloroglucinol compounds, or FPCs.

The next step in this study was to track wild koalas in a eucalyptus woodland. The scientists found that they were able to use the taste preferences of the captive koalas, based on chemical composition, to predict the tree preference of wild koalas. In addition, the scientists found that koalas spent more time in larger trees that were surrounded either by smaller, less-tasty trees or by larger trees that were equally tasty. Using this combination of leaf chemistry, tree size, and spatial environmental data, scientists hope to map koala habitats based on habitat quality, as a koala would see it.

The Future of Koala Habitats

All of this koala habitat mapping may prove very useful as the concentration of carbon dioxide continues to increase in the atmosphere. Other laboratory studies have shown that increases in carbon dioxide cause the concentration of toxins or compounds that otherwise interfere with digestion in eucalyptus leaves to increase. By studying how increased concentrations of carbon dioxide would affect the chemical composition of various Eucalyptus species, scientists may be able to predict which areas contain habitat that would most likely be of high quality for koalas in the future, and work to protect these areas.

More to Explore

The Demise of the Cavendish Banana

bananas

The Cavendish variety accounts for nearly 100% of the bananas imported around the world. (Photo credit: Muellek Josef/Shutterstock)

Whether sliced into a bowl of cereal, split in two and served with ice cream, or peeled and eaten, the banana is a common part of the American diet. Americans eat more bananas annually than oranges and apples combined. Bananas are an excellent source of vitamins, including B6 and C, magnesium, potassium, and fiber. While Americans typically view bananas as a snack food, in other parts of the world, they hold a much more important nutritional role. In some areas of Africa, where more than 200 species of the fruit are grown, bananas account for 80% of consumed calories. However, the banana that you know and love – a variety called the Cavendish – is in danger of being wiped out by a catastrophic disease currently spreading across the globe.

[Read more…]

The 411 on Fjords

(Photo credit: Stefan Auth/imagebroker RF/Photolibrary)

Fjords are a spectacular part of the Norwegian landscape. (Photo credit: Stefan Auth/imagebroker RF/Photolibrary)

Fjord is a Norwegian word describing a long, narrow inlet of water with steep cliffs on either side. Norway has the world’s highest concentrations of fjords. [Read more…]

Are We in a New Epoch? The Case for the Anthropocene

freeway

The proliferation of concrete on Earth’s surface is one piece of evidence scientists suggest supports the designation of a new epoch called the Anthropocene. (Photo credit: UpperCut Images/Alamy)

The Holocene Epoch began around 12,000 years ago. Are we now in the Anthropocene? In a recent study published in Science magazine, some scientists argue that we indeed have entered a new epoch. [Read more…]

Botanic Gardens Help Protect Threatened Plant Species

botanic garden

Botanic gardens are home to a large percentage of threatened plant species. (Photo credit: ©Wikimedia Commons)

While botanic gardens might seem like just a pretty or relaxing place to visit, it turns out they hold a very important role in the global conservation and preservation of threatened and endangered plant species. However, some researchers think botanic gardens should be taking an even bigger part in ensuring that threatened and endangered plant species are protected from extinction. [Read more…]

Solar Power Savings

solar panels

Switching from coal to solar power could save thousands of lives, according to new research. (Photo credit: Digital Vision/Getty Images)

Transitioning from coal to solar power in the United States could prevent the premature death of nearly 52,000 Americans annually, according to a study recently published in the journal Renewable and Sustainable Energy Reviews.

[Read more…]

A Closer Look at the Environmental Consequences of Fracking

wastewater from fracking

This containment pond holds contaminated water produced by the fracking process. (Photo credit: Dwight Nadig/E+/Getty Images)

While not exactly a new technology, fracking (which is short for “hydraulic fracturing”) has been a common topic in the news recently. Fracking is known both for its potential to ease U.S reliance on foreign sources of energy and for its possible adverse effects on the environment, which scientists now think include the potential for starting earthquakes.
[Read more…]

Cameroon’s Mysterious Crater Lakes

(Photo credit: Harri's Photography/Flickr Open/Getty Images)

Though picturesque, some crater lakes hide a deadly secret. (Photo credit: Harri’s Photography/Flickr Open/Getty Images)

August 21, 1986 started out as a normal day near Cameroon’s Lake Nyos. By the end of the day, however, 1746 people and 3500 livestock in the area would be dead. The cause of the catastrophe was, of all things, an exploding lake. But what caused the lake to explode? More importantly, could it happen again? [Read more…]

Harnessing Earth’s Energy in Iceland

Iceland geothermal plant

Geothermal energy is a significant part of Iceland’s renewable energy program. (Photo credit: naten/Shutterstock)

Iceland is known for its dramatic fire and ice landscape. Visitors come from all over the world to soak in the island nation’s thermal pools, which are heated naturally by underground plumes of magma. However, this geothermal energy is harnessed for more than just recreational purposes – it is also used as an important source of renewable energy in the country and even beyond its borders.   [Read more…]