India’s Tiger Sanctuaries

Bengal tigers

As of 2014, the worldwide population of Bengal tigers numbered 2226. (Photo credit: Swapan Photography/Shutterstock)

Over a century ago, more than 100,000 Bengal tigers roamed India. Today, there are just over 2200. What caused such a drastic drop in numbers? And what can be done to save the Bengal tiger from extinction? [Read more…]

20 Eco-Friendly Tips to Reduce Your Impact on the Environment

Earth

Earth Day was founded in 1970 by Senator Gaylord Nelson.  (Photo credit: Loskutnikov/Shutterstock)

April 22 marks the 48th annual celebration of Earth Day. Senator Gaylord Nelson of Wisconsin founded Earth Day in 1970 to bring environmental issues to the top of the national agenda. Until then, there were little to no legal or regulatory mechanisms to protect the environment. [Read more…]

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…]

Let’s Talk Loons

common loon and chick

Common loons protect their young chicks by carrying them on their back. (Photo credit: Roberta Olenick/All Canada Photos/Getty Images)

The echoing call of a common loon across a misty lake is a haunting, ethereal sound. Few who have heard it can soon forget it. Recognizable by their distinctive black and white coloration, loons are common sights during the late spring through early fall months on lakes across the northeastern states and portions of the Upper Midwest. [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…]

The Mountain Gorillas of Rwanda

mountain gorilla

The mountain gorillas of Rwanda are the only primate species in the world that is growing in number, making this critically endangered species a success story.  (Photo credit: erwinf/Shutterstock)

The mountain gorillas of war-torn Rwanda are making a comeback. [Read more…]

Quinoa: The Mother Grain

harvesting quinoa

The quinoa boom has greatly benefited Altiplano farmers and their families. (Photo credit: David Mercado/Reuters/Corbis)

In recent years, quinoa (pronounced “keen-wah”) has gained wide popularity around the world.

[Read more…]