Author Archives: SarahSpeckmaier

Eggs on Legs: How a Species was Divided by Song

More Than Just a Tune

Take a walk outside and listen for a moment – odds are you’ll hear a variety of birdsongs functioning as nature’s own soundtrack. While birdsongs are known and enjoyed by many, a lesser known fact is that these songs actually define separate species, or populations of animals that don’t mate with one another. Recently, scientist Benjamin Freeman made a fascinating discovery. With the help of birdsong, he determined that a population of Rusty-breasted Antpittas, previously thought to be one species, should actually be classified as two separate species.

https://upload.wikimedia.org/wikipedia/commons/9/95/Ochre-breasted_Antpitta_2.jpg

The Rusty-breasted Antpitta. Image source: Tony Castro

 

How it Happened

Rusty-breasted Antpittas, which are small birds native to Central and South America, are affectionately referred to as “eggs on legs” due to their small size and round shape. The Antpittas which Freeman investigated in his 2018 study live in the Andes, and travel by hopping and running. Because the birds are unable to fly, the mountains and valleys within the Andes form geographical barriers between groups of Antpittas.

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The Andes Mountains. Image source: Lucia Barreiros da Silva

 

Over the past few million years, the northern and southern groups of Antpittas evolved differences in their songs and genetics due to this separation. These differences, in fact, are so great that Freeman believes the two groups to be separate species – that is, they would not mate if they were to encounter one another. For an insider view of how Freeman believes the two populations have become separate species, check out the video below.

https://www.youtube.com/watch?v=RQU3cPAofeE&feature=youtu.be

 

What is Speciation?

The process of a population separating into multiple species, as seen in the Rusty-breasted Antpitta, is referred to by scientists as speciation. A common cause of speciation is when populations are separated by geography – in the Antpitta’s case, the barriers were formed by the mountains and valleys of the Andes. And as climate change causes temperatures to rise, this effect can become even more extreme: species move to higher elevations in order to reach their preferred temperature ranges, causing populations to separate even further and develop more differences. The podcast below paints a more detailed picture of speciation, and how the presence of different species can make the world we live in a more exciting and colorful place.

 

A Final Note

The story of the Rusty-breasted Antpitta is just one example of the processes that are occurring around us all the time. From birds, to bugs, to beluga whales, each species on Earth has unique traits that were formed by years of speciation. So the next time you step outside and find yourself listening to birdsong, take a minute to appreciate it – chances are, it’s more meaningful than you might have thought!

 

By Olivia Campbell, Morgan Kaye, Kevin Keum, & Sarah Speckmaier

 

Eruption Incoming: Sound Waves Help Scientists Predict Volcanic Eruptions

A Precautionary Tale

If you’re like most people, the words “volcanic eruption” probably spark fear into your mind: rumbling earthquakes, hot lava, and volcanic ash likely aren’t something you want to encounter. Luckily, a recent discovery allows scientists to accurately predict volcanic eruptions, keeping people safe both on the ground and during air travel.

Warning System at Work

Geophysicist Maurizio Ripepe has made a historical achievement by discovering a method for detecting volcanic eruptions before they happen. Ripepe’s system, which is the first in the world to successfully predict volcanic eruptions, is currently in use at Mount Etna, Europe’s largest active volcano. The warning system, which relies on vibrations made by sounds too low for humans to hear, alerts authorities near Mount Etna about an hour before the eruption will take place. Since its beginnings in 2010, the warning system has successfully predicted 57 out of the 59 eruptions that have taken place at Mount Etna.

File:Etna Volcano Paroxysmal Eruption October 26 2013 - Creative Commons by gnuckx (10491835855).jpg

Eruption at Mount Etna that took place in October 2013. Source: Wikimedia Commons

 

How Does it Work?

The warning system devised by Ripepe relies on infrasound waves, which are extremely low vibrations that are produced by volcanoes before an eruption. As gas rises out of a volcano’s magma before an eruption, it causes air movement within the craters, producing sound waves. Much like a musical instrument, the shape of the craters affects the kinds of sounds that are produced. These infrasound waves are then detected by the warning system, indicating that an eruption will happen soon. At Mount Etna, which is an open-vent volcano, the exposed magma provides plenty of gases to produce the infrasound waves that alert the warning system. Volcanoes with closed vents make early detection a little more difficult – a challenge scientists are continuing to tackle.

Video describing an infrasound detection system. Source: CTBTO

 

Looking to the Future

The success of Ripepe’s warning system at Mount Etna has paved the way for many more advancements in predicting volcanic eruptions. Scientists believe similar technology can be applied to volcanoes around the world, even those with different structures than Mount Etna. Although volcanoes still pose a threat to human safety, hopefully we’ll be able to rest a little easier knowing that warning systems can help people stay safe.

Two’s a Crowd: Liver Disease Risk Increases With Multiple Risk Factors

Why It Matters

If you’re a health-conscious sort of person, you probably already know that keeping a healthy diet and living an active lifestyle can reduce your risk of certain health problems – for instance, liver disease. But did you know that exposure to certain chemicals can influence your liver’s health for the worse?

How Tough is Your Liver?

When faced with handling its typical everyday duties, the liver is a very resilient organ. It can easily recover from the early stages of damage that may lead to liver disease, such as having a few drinks in one night. However, when the number of risk factors concerning the liver begins to add up, the likelihood of developing non-alcoholic fatty liver disease increases. Included in the list of risk factors that may pose a threat is the presence of certain chemicals in the environment.

Diagram of the liver in the human body. Source: Wikimedia Commons

 

PCBs: A Potential Threat

Two chemicals that may pose a threat to your liver’s health are vinyl chloride, an industrial chemical, and polychlorinated biphenyl compounds (PCBs), which are oily liquids used in electrical equipment. PCBs have been banned since the 1970s due to their health risks, but unfortunately, they break down very slowly and as a result are oftentimes still present in air, water, and soil sources across the globe. Currently, the greatest potential source for coming into contact with PCBs is through consuming animal products. Recent studies by the Environmental Protection Agency revealed that the maximum concentration of PCBs is just a few parts per billion (ppb) in fish, and even less for meat and dairy. These levels are considered safe for humans, though people who eat large amounts of seafood may be at higher risk.

Structure of a polychlorinated biphenyl compound. Source: OSPAR

 

Healthy Choices Can Reduce Your Risk

However, experts agree that for most people, there’s no need to panic – the effects of these chemicals were only seen to be harmful when combined with additional unhealthy lifestyle factors such as obesity or a diet with a large excess of calories. Just look to rodents for an example: in lab experiments, only the obese mice which were fed excessive amounts of food suffered from the chemicals’ harmful effects, while the healthy mice were not affected by the chemicals. It’s only when faced with additional risk factors, such as obesity, lifestyle, or genetics, that it becomes necessary to pay extra attention to your liver’s health by watching out for the warning signs of liver damage.

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Video explaining the warning signs of liver damage. Source: Intan Farisha

 

A Final Note

The good news is that for an active person of a healthy weight, these chemicals likely don’t pose a cause for concern. So don’t worry, your liver is probably going to be just fine – as long as you remember to eat your veggies and go for a jog once in a while!