Publications browsing by category


Invaders’ “Away-Field Advantage” Not as Strong as Once Thought

Thursday, May 16th, 2013

Brown tree snakes (Boiga irregularis) caused the local extinction of more than half of Guam's native birds and lizards after it invaded the island in the 1940s. (National Park Service)

Brown tree snakes (Boiga irregularis) caused the local extinction of more than half of Guam’s native birds and lizards after they invaded the island in the 1940s. (National Park Service)

by Kristen Minogue

For decades, ecologists have assumed the worst invasive species—such as brown tree snakes and kudzu—have an “away-field advantage.” They succeed because they do better in their new territories than they do at home. A new study led by the Smithsonian Environmental Research Center reveals that this fundamental assumption is not nearly as common as people might think.

Click to continue »

Weddell Seals Have Most Adult-Like Brains of any Mammal at Birth

Thursday, May 2nd, 2013

by Kristen Minogue, Regina Eisert and Olav Oftedal

Because they must lean to navigate under sea ice in just over a month, baby Weddell seals are born with near adult-sized brains. (Samuel Blanc)

Because they must learn to navigate under sea ice in just over a month, baby Weddell seals are born with near adult-sized brains. (Samuel Blanc)

When it comes to brain size, Homo sapiens generally get the most credit. But to find the baby mammals with the proportionally largest brains on the planet, Smithsonian scientists had to search in Antarctica. In a study published online in April, they found Weddell seal pups have the most developed brains at birth recorded for any mammal so far.

By the time they are born, baby Weddell seal brains have already reached 70 percent of their adult size. (The brain of a human infant is a mere 25 percent of its adult size.) But the researchers found this rapid development carries a hefty price tag.

Click to continue »

Earthworms jeopardize orchid growth

Friday, March 29th, 2013

by Kristen Minogue

Lumbricus rubellus, a European earthworm that is now one of the most common in the eastern U.S.  More than 10,000 years ago, Pleistocene glaciers wiped out native earthworms. Today virtually all earthworms in the U.S. north of Pennsylvania are invasive. (Holger Casselmann)

Lumbricus rubellus, a European earthworm that is now one of the most common in the eastern U.S. More than 10,000 years ago, Pleistocene glaciers wiped out native earthworms. Today virtually all earthworms in the U.S. north of Pennsylvania are invasive. (Holger Casselmann)

Most gardeners consider the sight of an earthworm writhing in the dirt a good omen. The slimy invertebrates chew up and churn up the soil, making it easier for vegetables and flowers to access nutrients.

But for wild orchids, they’re more of a menace. Earthworms could prevent roughly half a forest’s orchid seeds from even germinating, ecologists from Smithsonian Environmental Research Center and Johns Hopkins University discovered in a study published online this March in Annals of Botany Plants.

The small size of orchid seeds (they are barely the size of dust grains) makes them particularly vulnerable. As earthworms chew up forest litter, they ingest orchid seeds as well. When that happens, two things can keep the seeds from germinating: One, the process of passing through an earthworm’s gut can render them unviable. Or two, if the seeds survive ingestion, they can end up buried so deep that they can’t access the fungi they need to germinate and grow. As a general rule, deeper soils are much less likely to have those fungi.

Click to continue »

Milk before dinosaurs? The evolution of a household beverage

Monday, November 26th, 2012

by Kristen Minogue

Artist's depiction of the prehistoric synapsid Varanodon agilis (left) under attack from an ancient amphibian. (Wikimedia Commons/Smokeybjb)

Milk—the white, calcium-rich liquid common to mammals and refrigerators across the globe—may have evolved long before the mammals that secrete it. It may have evolved even before dinosaurs. It’s an idea SERC lactation expert Olav Oftedal proposed a decade ago and is now gaining momentum among biologists who study the evolution of what we drink.

Click to continue »

Climate Change Stimulates Growth of Invasive “Super Weed”

Thursday, November 8th, 2012

by Kristen Minogue

Tom Mozdzer explores a patch of invasive Phragmites in SERC's global change wetland.

Is it better to be a jack of all trades or a master of some? In the plant world, it’s possible to do both–and that could make a huge difference in deciding which plants dominate under climate change. This holds especially true for one: the invasive reed Phragmites australis. Its ability to alter its anatomy enables it to grow well in just about any environment, including one spiked with CO2 and nitrogen, SERC ecologists discovered in a study published Oct. 31.

Plants like this are called “jack-and-master” plants. Typically, the most competitive plants surpass their neighbors through one of two strategies. “Jack-of-all-trades” plants do moderately well under most scenarios. Their competitors will surpass them when conditions are good, but if the environment becomes stressful, the jack of all trades will grow better. “Master-of-some” plants do very well under only a few conditions, so if the environment shifts in their favor, they are certain to emerge victorious. But a few types—the jack-and-master plants—can use both tactics. And the invasive Phragmites is one of them.

Click to continue »

Invaders escape persecution from parasites

Tuesday, February 7th, 2012

by Monaca Noble

Invasion was a godsend for the rough periwinkle snail, which managed to escape its flatworm parasites. (World Register of Marine Species)

Most organisms have several types of parasites associated with them. However, when species are introduced, they may lose some of their natural parasites through the invasion process. Or sometimes, parasites that survive the journey don’t do very well in the new environment. In essence invasion acts as a filter limiting the number of parasites that are transported and introduced. In science this process is called the parasite escape hypothesis.

Take the common cat parasite Toxoplasma gondii. T. gondii‘s complex two-host life cycle makes it difficult for it to adapt to new places. The parasite has two phases, a sexual phase and an asexual phase. The sexual phase can only take place in the cat (primary host), but the asexual phase can occur in several mammal species (secondary host) including cats, mice, humans, and birds. Because the parasite must infect a cat to reproduce and survive, its preferred secondary host is a mouse. If a mouse infected with T. gondii were introduced into an area with no cats, the parasite would not be able to survive.
Click to continue »

Toughest Shellfish in the Sea?

Tuesday, January 24th, 2012

by Kristen Minogue

Blue mussels (Credit: Meriseal)

Some species can survive just about anywhere. Take blue mussels, a group of shellfish whose habitat stretches from the Arctic to the Mediterranean. Over the last several decades, biologists have thrown all kinds of tests at them – heat, cold, saltwater, freshwater, low oxygen. They’ve even tried drying them out. Almost nothing fazes these animals. For invasion scientists trying to figure out how far they could spread, that’s a scary prospect.
Click to continue »

Snowmageddon vs. Caribbean Creep

Monday, January 9th, 2012

by Monaca Noble

SERC's Green Village during Snowmageddon February 2010 (Stephen Sanford)

Remember Snowmageddon 2010, the east coast storms that dumped up to three feet of snow over the mid-Atlantic? The February snowstorm was the largest in the region in nearly 90 years, resulting in the heaviest snowfall on record for Delaware (26.5 inches) and the third heaviest snowfall in Baltimore (24.8 inches). The storm made a big impression on Dr. João Canning-Clode and other scientists at the Smithsonian Environmental Research Center, who began to wonder if the storm, and the December/January cold snap that preceded it, would lead to the deaths and potential disappearance of marine invaders from southern climates.
Click to continue »

How Plants (Occasionally) Escape the Food Chain

Friday, December 23rd, 2011

by Kristen Minogue

Leaf shredded by insects. Credit: Marina LaForgia

It’s a trick worthy of any spy thriller: to elude an enemy, hide among something it won’t notice. Or, to be extra safe, something it finds incredibly disgusting. It turns out the same strategy can work for plants that don’t want to get eaten. Sometimes.

For the last seven months, intern Marina LaForgia has kept tabs on tree saplings in more than a dozen different environments and watched the game of ecological survival play out. As she tracked their progress, she searched for an answer to a deceptively simple question: Is diversity good for plants? When it comes to the food chain, will hungry herbivores pass over tasty plants if they’re surrounded by less palatable ones?
Click to continue »

Why We Like Science

Friday, November 4th, 2011

Above: One perk of student research at SERC. Photo courtesy of the Phytoplankton Lab

It’s impossible to work here without some compulsion to understand the natural world – whether it’s colonial tunicates that bear a creepy resemblance to the Borg or endangered orchids that need microscopic fungi to survive. So when Smithsonian Magazine launched a “Why I Like Science” series on their blog Surprising Science, we took full advantage of the opportunity to share our enthusiasm. Here’s how four staff responded when asked why science is cool.

Click to continue »