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Category Archives: biology

Hostile invader: Ladybug species carries spores that kill competitors

Invasive species have become a problem on nearly every continent, where native species that may have had millions of years to adapt to their environment are somehow trivially displaced by a species that originated somewhere else. How is it that the invaders can be so phenomenally successful against what should be a well-entrenched competition?

A new study shows that in at least one case, some insect invaders engage in a bit of biological warfare, carrying a fungus that kills their competitors (the host can tolerate the fungus). The fungus spreads because of a nasty habit the insects have—namely that they tend to eat each others' eggs. Somewhat ironically, all of this goes on in a species that tends to have a friendly reputation: the ladybug (or ladybird, for the anglophiles among us).

The invasive species in question is an Asian ladybug, the harlequin ladybird Harmonia axyridis. Because of its fondness for agricultural pests (fondness in the same sense that I have a fondness for lobster) Harmonia has been introduced to some countries where it wasn't native. When the invaders were introduced, the native ladybug species dropped like flies (pun intended), being easily displaced by the new arrivals.

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Carbon in Alaskan soils stays stored despite warming

A greenhouse in winter, with the rest of the tundra frozen around it.
Josh Schimel

Although the climate changes that are being driven by human carbon emissions are likely to cause serious disruptions on their own, one of the additional worries is that the initial warming will set off events that keep changing the planet even if humanity gets its carbon emissions under control. So, for example, warming the oceans could heat up the clathrates that exist there, releasing methane that greatly enhances the greenhouse warming.

The other place that scientists have been watching nervously is the Arctic. About half the carbon stored in the Earth's soil is in the Arctic, where it's locked in place by permafrost and low metabolic activity caused by the cold. As those regions melt, the worry is that bacteria in the soil will start feeding on the carbon trapped there, releasing it into the atmosphere as CO2 that causes further warming.

A new study that looks at 20 years of changes in Alaska, however, suggests that this won't necessarily take place. In the area being studied, the warming temperatures rearranged the ecosystem and redistributed the carbon. But, in the end, there was just as much carbon stored in the soil. What needs to be determined now is just how well this experience will translate to other areas of the Arctic.

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Carnivorous plant has deleted most of its junk DNA

The business end of a bladderwort, ready to suck in prey.
Enrique Ibarra-Laclette, Claudia Anahí Pérez-Torres and Paulina Lozano-Sotomayor.

Over the weekend Nature released a paper that describes the genome of a fascinating creature with a rather unglamorous name: the bladderwort. These plants live in swampy or liquid environments and find it hard to get sufficient nutrients there, so in order to survive the plants have turned carnivorous. The bladders that give the group of related species its name are actually feeding organs. When an organism brushes up against their triggers, the bladders swell by sucking in the surrounding water, along with any organisms it carries. They then seal off, allowing the plant to digest its prey.

The oddities continue at the molecular level. The genome of this bladderwort, Utricularia gibba, contains more genes than are found in the human genome (something common in plants). But it carries them all in a compact genome that's only a bit over 2 percent of the size of the human version. It does this largely by getting rid of just about everything that could possibly be considered superfluous—which may tell us important things about whether most of the DNA we carry really is superfluous.

First, the details, then some perspective.

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Carnivorous plant has deleted most of its junk DNA

The business end of a bladderwort, ready to suck in prey.
Enrique Ibarra-Laclette, Claudia Anahí Pérez-Torres and Paulina Lozano-Sotomayor.

Over the weekend Nature released a paper that describes the genome of a fascinating creature with a rather unglamorous name: the bladderwort. These plants live in swampy or liquid environments and find it hard to get sufficient nutrients there, so in order to survive the plants have turned carnivorous. The bladders that give the group of related species its name are actually feeding organs. When an organism brushes up against their triggers, the bladders swell by sucking in the surrounding water, along with any organisms it carries. They then seal off, allowing the plant to digest its prey.

The oddities continue at the molecular level. The genome of this bladderwort, Utricularia gibba, contains more genes than are found in the human genome (something common in plants). But it carries them all in a compact genome that's only a bit over 2 percent of the size of the human version. It does this largely by getting rid of just about everything that could possibly be considered superfluous—which may tell us important things about whether most of the DNA we carry really is superfluous.

First, the details, then some perspective.

Read 9 remaining paragraphs | Comments

Carnivorous plant has deleted most of its junk DNA

The business end of a bladderwort, ready to suck in prey.
Enrique Ibarra-Laclette, Claudia Anahí Pérez-Torres and Paulina Lozano-Sotomayor.

Over the weekend Nature released a paper that describes the genome of a fascinating creature with a rather unglamorous name: the bladderwort. These plants live in swampy or liquid environments and find it hard to get sufficient nutrients there, so in order to survive the plants have turned carnivorous. The bladders that give the group of related species its name are actually feeding organs. When an organism brushes up against their triggers, the bladders swell by sucking in the surrounding water, along with any organisms it carries. They then seal off, allowing the plant to digest its prey.

The oddities continue at the molecular level. The genome of this bladderwort, Utricularia gibba, contains more genes than are found in the human genome (something common in plants). But it carries them all in a compact genome that's only a bit over 2 percent of the size of the human version. It does this largely by getting rid of just about everything that could possibly be considered superfluous—which may tell us important things about whether most of the DNA we carry really is superfluous.

First, the details, then some perspective.

Read 9 remaining paragraphs | Comments

Carnivorous plant has deleted most of its junk DNA

The business end of a bladderwort, ready to suck in prey.
Enrique Ibarra-Laclette, Claudia Anahí Pérez-Torres and Paulina Lozano-Sotomayor.

Over the weekend Nature released a paper that describes the genome of a fascinating creature with a rather unglamorous name: the bladderwort. These plants live in swampy or liquid environments and find it hard to get sufficient nutrients there, so in order to survive the plants have turned carnivorous. The bladders that give the group of related species its name are actually feeding organs. When an organism brushes up against their triggers, the bladders swell by sucking in the surrounding water, along with any organisms it carries. They then seal off, allowing the plant to digest its prey.

The oddities continue at the molecular level. The genome of this bladderwort, Utricularia gibba, contains more genes than are found in the human genome (something common in plants). But it carries them all in a compact genome that's only a bit over 2 percent of the size of the human version. It does this largely by getting rid of just about everything that could possibly be considered superfluous—which may tell us important things about whether most of the DNA we carry really is superfluous.

First, the details, then some perspective.

Read 9 remaining paragraphs | Comments

Carnivorous plant has deleted most of its junk DNA

The business end of a bladderwort, ready to suck in prey.
Enrique Ibarra-Laclette, Claudia Anahí Pérez-Torres and Paulina Lozano-Sotomayor.

Over the weekend Nature released a paper that describes the genome of a fascinating creature with a rather unglamorous name: the bladderwort. These plants live in swampy or liquid environments and find it hard to get sufficient nutrients there, so in order to survive the plants have turned carnivorous. The bladders that give the group of related species its name are actually feeding organs. When an organism brushes up against their triggers, the bladders swell by sucking in the surrounding water, along with any organisms it carries. They then seal off, allowing the plant to digest its prey.

The oddities continue at the molecular level. The genome of this bladderwort, Utricularia gibba, contains more genes than are found in the human genome (something common in plants). But it carries them all in a compact genome that's only a bit over 2 percent of the size of the human version. It does this largely by getting rid of just about everything that could possibly be considered superfluous—which may tell us important things about whether most of the DNA we carry really is superfluous.

First, the details, then some perspective.

Read 9 remaining paragraphs | Comments

Infecting mosquitos with bacteria could block malaria

Mosquito bites kill an estimated 1-2 million people every year. It is not the mosquitoes’ fault, though—it's the pathogens they transmit that are lethal, not the bites themselves. Nets and insecticides can help, but they can also be costly, logistically difficult to distribute, and not particularly green. So alternative strategies to prevent disease transmission are needed.

Wolbachia are bacteria that reside in insect cells and have a very complicated relationship with their hosts. They can render mosquitoes resistant to certain pathogens, and they can reduce mosquitoes' lifespans, which is significant because it is often the older mosquitoes that transmit the pathogens that make us sick. Wolbachia infect up to 76 percent of the 2-5 million insect species on Earth—but not, of course, the mosquito species that carry dengue fever or malaria. That would be far too convenient.

So researchers have been trying to infect disease-carrying mosquitoes with Wolbachia in the lab and then let these infected mosquitoes out into the wild to mate with and infect disease-carrying strains in order to reduce disease transmission. This has in fact already happened in northeastern Australia, where researchers spent four years maintaining Wolbachia in mosquito cells in the lab before letting infected mosquitoes loose in January 2011 to infect wild Aedes aegypti, the mosquitoes that transmit dengue fever. The trial is going so well that it is being repeated in Vietnam.

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Birds and the feather did not evolve together

Illustration of Microraptor, which is thought to have had iridescent feathers.
Mick Ellison/AMNH

“Which came first, the chicken or the egg?” Evolutionarily speaking, it’s a yawn of a conundrum. We know it was the egg, which evolved (with shell to enable a terrestrial lifestyle) some 300 million years ago, long before a chicken first clucked across a patch of open ground.

In between the origin of the egg and the domestication of the chicken, however, there are plenty of other interesting features to consider. Take the feather. There were hints of a revolution 150 years ago when part-dinosaur, part-bird archaeopteryx was discovered. Recently, discoveries in China have pulled back the curtain to reveal a varied cast of feathered dinosaurs, and we've found it wasn't just the direct ancestors of birds that were sporting down coats.

These discoveries have made the question of evolutionary origins even more interesting. At one point, you could have wondered whether feathers—which are basically made of the same stuff as scales— arose directly to aid flight or had been co-opted for the purpose from some other function. The prevalence of feathers and feather-like structures in flightless organisms points to the latter. So when did they first appear, and what were these other functions?

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The rise of a frog-killing fungus pinned in part on global trade

It’s a tough time to be a frog. A fungal disease known as chytridiomycosis has been decimating populations across the planet for about a decade. Since its discovery in the late 1990s, it has already wiped out about 100 species. Although it seemed to appear suddenly, a team of scientists has now published the evolutionary history of the fungus, which suggests that chytridiomycosis has been killing amphibians for thousands of years.

The fungus, Batrachochytrium dendrobatidis, damages amphibian skin, often with fatal consequences, because these creatures use their skin to absorb water and electrolytes they need. The infection spreads primarily through skin-to-skin contact, but a form of the fungus called a zoospore can persist in wet environments for months. Though the spread and impact of the disease have been well-documented, the reason for the rising infection rate remained under debate.

When a scary new infectious disease starts spreading, scientists need to learn why the pathogen has suddenly become so deadly in order to understand how to protect at-risk populations. Epidemiologists know that a deadly disease doesn’t just emerge from thin air—either an existing pathogen evolved into a new, more virulent form, or something about the affected species or its environment has changed to increase its susceptibility.

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