This Week in Science: August 24-30 2013

Scientists uncovered the largest fish ever and it has one of my favorite scientific names: Leedsichthys problematicus.

“How many species of non-avian dinosaur were there? We will probably never know the definite total, but we can be sure that there were both more and less dinosaur species than have been named to date.”

Hellbenders are making a comeback.

10 years of weather in 3 minutes.

170 year of hurricanes mapped across the globe.

New Australian fossils might help to fill the gap in the fossil record.

The British Geological Service has a 3D database of fossils.

12 animal adjectives.

These baby snapping turtles will crawl right up to your front door.

Young and old whales alike serenade the ladies.

Don’t wash raw chicken!

Scientists have discovered a new element.

Sleeping for 8 hours is a relatively recent development.

Were terror birds herbivores?

What causes Namibia’s ‘fairy circles‘?

Pterosaurs were massive and amazing, but how did they fly?

The Yosemite Rim Fire is terrifying and oddly beautiful.

Scientists recently discovered a ‘walking’ shark.

This baby pangolin is just too cute!

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What Makes a Species?

What is a species? At first, that seems like a simple question. Species is probably the most commonly discussed rank of the taxonomic hierarchy, but it is by no means simple.

The most prevalent definition of a species relies on the biological species concept. To be a species, individuals must be able to interbreed and produce viable offspring. In other words, the offspring must also be able to produce more offspring. For example, horses and donkeys are able to mate, but their offspring (mule) are sterile. Therefore, donkeys and horses are different species, but that is obvious by looking at them. What if you couldn’t tell by looking at them? Even with the sophistication of DNA technology, most species descriptions rely on morphology, or what the organisms look like.

There could be a variety of reasons why individuals cannot, or do not, interbreed. If two species are separated by a geographic feature, such as the Appalachian Mountains or the Mississippi River, they will not be able to interbreed because they are spatially disjunct. Over time, the species will probably change and become more and more different. What if two species breed at different times of the year? They will not be able to interbreed because the don’t breed at the same time. Or what if two species do live in the same place, but have unique calls or genitalia that are incompatible? They can’t interbreed. What about two species of plants that have different numbers of chromosomes? They won’t be able to reproduce viable offspring.

Variation within a ‘ring species’ (via Wikimedia Commons)

Sometimes species are difficult to distinguish just by looking at them. For example, the Western meadowlark and the Eastern meadowlark look virtually identical and their ranges overlap. However, their songs are different and they don’t interbreed, despite looking alike. Some organisms are called ‘ring species’. Imagine a species of snakes at lives around a lake. Surrounding the lake are different subspecies that are adapted to the local conditions and each of these subspecies can breed with the neighboring subspecies until you reach a point where the ends of the rings overlap. There the two subspecies cannot breed. Where did the snake population shift from one species to another? Are they all the same species? And what about species where individuals look radically different from each other? In many organisms, males and females look very different. For example, in some species of iguana there are three different morphotypes: the big males, the small females, and the small males. Unless you studied their behavior, it would be difficult to determine whether they belonged to the same species.

But what if you couldn’t observe behavior? That is a core problem in paleontology and it shows itself in two different ways: chronospecies and lumpers v. splitters. When scientists study fossil organisms, we are limited to morphology because bones do not preserve behavior. We have no way of knowing whether or not organisms could still interbreed after millions of years. Could a theropod dinosaur from the Early Cretaceous breed with theropod from the Late Cretaceous? Another challenge is the scarcity of fossils. Paleontologists might only find a handful of bones and from them extrapolate and describe an entire individual. However, that comes with consequences. When is variation too insignificant to justify naming a whole new species? Are the differences just normal variation? There are two primary schools of thought: lumping and splitting. Lumpers tend to allow more variation within their species, while splitters allow very little. Dinosaur paleontologists tend to be the most prolific splitters.

It can be difficult to describe what makes a species and some organisms are more complicated than others. It is vital to remember that even though classification systems make biology more manageable, everything has been devised by humans. Science is constantly changing and adapting to new observations, but it is simply attempting to describe what we know. Nature does not fit into little boxes.

This Week in Science: August 17-23 2013

Some female bugs pretend to be males of a different species to avoid ‘stabbing sex’.

A whale carcass can feed polar bears for a long time.

Speaking of whales, here’s how scientists perform a whale autopsy.

Sometimes sharks ate dinosaurs.

What made early mammals special?

Neil deGrasse Tyson on the meaning of life.

‘If Mary Anning had been the only woman to wander the coast with geological intent, there would be no mystery‘.

You can see the California wildfires from space.

‘Multitaskers Make the Best Lovers, Say Tree Frogs‘.

How earthquake waves move and how we measure them.

This poor aphid.

This might be the coolest night-light that I’ve ever seen.

19th century paleontology has its pros and cons.

Male big horn sheep are either sexy or long-lived.

The importance of science outreach.

Climate change might be helping the redwoods.

How many eggs did dinosaurs lay?

Gender is complicated.

’16 Things BuzzFeed Doesn’t Know About the Ocean‘.

This Week in Science: August 10-16 2013

The Smithsonian aims to collect genetic material from all species.

This is how to become a fossil.

Consider supporting this mobile museum!

Whale deadfalls are ecological hotspots.

How the extinction of megafauna impacted the Amazon.

How can you measure height on Mars without sea-level?

During the Cold War, we tried to put a copper ring around the Earth.

‘In North American Katydids, Green isn’t the Dominant Colour, Pink is‘.

Fears of ‘Testicle-Eating’ Fish Overblown

Urban beekeeping is probably not a good idea.

The olinguito, a carnivore discovered this week, is adorable.

Some lipsticks might contain heavy metals.

A decapitated copperhead rattlesnake attacks its own body.

Video of Perseid meteor exploding.

Taxonomic Hierarchy

Life is complex. In biology, scientists try to organize all of the living things on Earth through taxonomy. Taxonomy is a method of arranging these living things (taxis: arrangement, -nomia: method) and we have Linnaeus to thank for it.

Taxonomy is based on a hierarchy of classification; the lower you go in the hierarchy, the more closely related the living things are. These groups, from largest to smallest are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. When I was in high school, I learned a mnemonic to remember the order of taxonomic classification: Did King Phillip Come Over For Good Spaghetti?

To make classification simpler, let’s choose two species and follow them through the hierarchy. Let’s compare the domesticated cat (Felis catus) and humans (Homo sapiens).

The largest layer of the classification hierarchy is Domain. There are 3 domains: Archaea, Bacteria, and Eukarya. Cats and humans are in Eukarya, so we’ll follow that path.

The next layer is Kingdom. There are 6 kingdoms: Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria. Cats and humans are in Animalia, so we’ll follow that path.

Classification hierarchy (via Wikimedia Commons)

Next is Phylum. The kingdom Animalia contains about 35 phyla. Cats and humans are in Chordata.

Next we have Class. The lower we go in the hierarchy the more and more choices we have. Cats and humans are in the class Mammalia.

Next is Order. Up until this point, humans and cats have fallen under the same classification. Cats are in the order Carnivora, while humans are in the order Primates. In plants, the suffix -ales denotes an order.

Next we have Family. Now the groups are getting much smaller. Cats are in the family Felidae, while humans are in the family Hominidae. The suffix -dae is used to denote a family within animals, while in plants -aceae serves the same function.

Genus is a commonly used level of classification. Cats are in the genus Felis, while humans are in the genus Homo.

Species is the most specific (pun intended) level of classification. When writing a species name, both the genus and species names are required. Cats are Felis catus and humans are Homo sapiens.

These aren’t the only levels of classification. Between levels there are superorders and suborders and tribes and subspecies and other small levels of subdivision. For example, humans are part of the tribe Homini. The use of these subdivisions is an exception, not a rule. Many species makes it all the way through the taxonomic hierarchy without using any subdivisions.

The most important thing to remember when it comes to taxonomy is that this system was entirely made up by humans to explain the world around us. We’re not perfect and sometimes things don’t fit neatly into these little boxes and the entire tree of life has to be redrawn. Regardless, taxonomy is a useful way for scientists to categorize and understand the world.

This Week in Science: August 3-9 2013

The race to find ancient DNA was typically bad for fossils.

We probably will never clone non-avian dinosaurs.

Some awesome geeky videos.

Why does your voice sound funny on a recording?

How did dinosaurs have sex?

“The Top Ten Weirdest Dinosaur Extinction Ideas”.

What happens when a mosquito bites you is more terrifying than I thought.

Five amazing recent medical breakthroughs.

Rabbits might have white tails to help them escape.

Surprise! Pregnancy varies from person to person.

All 8 species of pangolin are endangered.

Was Joseph Leidy the loser (and winner) of the Bone Wars?

I need to check out the Moss Garden and Lemur Collection at Duke!

The British keep finding bodies under parking lots!

Paleontologists may have found fossil ambergris.

Why museum collections are important.

The baculum is a fascinating bit of anatomy.

New flying mammal found in a bushmeat market.

In honor of ‘Cooler than Shark Week’, Christie Wilcox wrote many posts about real shark research: An open letter to the Discovery Channel, sharks are in trouble, ‘Shark Cartilage Won’t Cure Cancer‘, a link roundup, bull sharks aren’t so scary, and real marine biologists are really cool.

David Shiffman, a marine biologist, talks about Shark Week.

C. megalodon was amazing, but it is extinct.

Is Shark Week bad for conservation?

Word Wednesday: Stromatolite

Nearly every biology class that I have ever taken has mentioned stromatolites. They are an essential part of the history of the Earth and are an easy term to understand.

stromatolite

Stromatolite breaks down into two parts: stromato and -liteStromato comes from the Greek word ‘stroma‘ which means bed or mattress and lite comes from the Greek word ‘lithos‘ which means stone. In other words, stromatolites were mattresses of stone.

Stromatolites growing in Hamelin Pool Marine Nature Reserve, Shark Bay in Western Australia. (Wikimedia Commons)

Stromatolites were microorganisms that lived up to 3.5 billion years ago and are some of the oldest fossils. They are ‘laminated organo-sedimentary structures formed by the trapping and binding, and/or precipitation of minerals by microorganisms‘, specifically by cyanobacteria (blue-green algae). In other words, they are made of layers and layers of cemented cells. They were typically no more than half a meter tall, but in some places were as large as 5 meters tall! Cyanobacteria is thought to have contributed to the high level of oxygen in the the atmosphere by undergoing photosynthesis. You can find these ancient fossils in places such as the Black Hills of South Dakota and the Upper Peninsula of Michigan. Today, the best known modern stromatolites are found in Shark Bay in Western Australia.

To learn more about stromatolites, check out the links below!

UC-Berkeley: Fossil Record of the Cyanobacteria

Shark Bay

AMNH: A stromatolite from Mauritania

Page Museum at the La Brea Tar Pits

Last December I had the wonderful opportunity to visit the Page Museum at the La Brea Tar Pits. I spent a week in southern California and the La Brea Tar Pits were without a doubt my favorite part!

First of all, let’s talk about the tar pits themselves. Before you even see the museum or the grounds, you can smell them; the smell of tar permeates Wiltshire Boulevard for blocks, especially on hot days. These tar pits have been around for tens of thousands of years and formed when crude oil oozed to the surface through cracks in the crust. After the oil reached the surface the lightest part of the ooze–the oil–evaporated, leaving behind the thick, sticky asphalt. Luckily for scientists (but unluckily for the animals), during the Pleistocene many plants and animals got stuck in the tar, and can now be studied. When you walk around the grounds today you can see tar pits large and small still bubbling away. In front of the museum is a massive pond with mammoth sculptures reenacting how these animals may have become stuck. Also on the grounds you can see Project 23 and some of the pits that scientists have been excavating for 100 years, as well as the Pleistocene Garden, a recreation of what the Ice Age flora was like.

Dire Wolf skulls, Page Museum, Los Angeles, CA (Wikimedia Commons)

Once you go inside the Page Museum itself, things are no less impressive. The museum is filled with some of the millions of specimens found at the site. Smilodon (saber-tooth cats) are some of the most well known fossils (it is the state fossil of California) and some of the bones even have evidence of injuries and disease. Unlike in museums in other states, large specimens such as mammoths and horses are suspended from the ceiling instead of mounted from the floor in case of earthquakes! One of my favorite exhibits was the wall of over 400 dire wolf skulls that was made to solve the problem of too many fossils and not enough storage.

In the middle of the museum is the Fishbowl Lab. For me, fossil preparation is one of the most exciting parts of the scientific journey. Visitors can watch volunteer preparators clean and repair fossils. You might even get a chance to see Zed, the largest and most complete mammoth found so far at the site!

If you find yourself in southern California, I highly recommend visiting the Page Museum at the La Brea Tar Pits. I could easily spend days in that museum and I would love to go back! To learn more about the tar pits, check out the links below!

Resources

UC-Berkeley: La Brea Tar Pits

The Page Museum

The Tar Pits blog

This Week in Science: July 27-August 2 2013

Why be monogamous? The debate continues.

Many people don’t understand what happens to women’s bodies during pregnancy.

An extinction to celebrate‘.

What ants have to do with chocolate and agriculture.

Where’s the male Pill?

If extraterrestrials are watching Earth, they’ll see that we move a lot.

Cat lovers: you don’t actually know what your cat is saying.

These 3-D printed hermit crab shells are breathtaking.

I mentioned Nabokov’s cabinet of butterfly genitalia in a post a few months ago.

The bubonic plague is endemic to rodents in the American West.

Another reason why Jurassic Park wouldn’t work: that mosquito couldn’t bite.

Awesome infographic about the evolution of brain size in humans.

The Most Famous Extinction‘ and why dinosaurs were not failures.

Drinking milk changed the world.

An adorable new species of lemur discovered.

Some moths are cooler than butterflies.

Sunsets are an optical illusion.

Watch the Earth breathe.

Fossils belong in museums.

Word Wednesday: Harry Potter Spells

And now for something completely different. July 31st is Harry Potter’s birthday, so I thought that it would be fitting to discuss how the spells in the world of Harry Potter can break down as easily as any scientific term.

Lumos

Lumos comes from the Latin word ‘lumen‘ which means light.  In the world of Harry Potter, Lumos is a basic spell that produces a beam of light from the caster’s wand.

Nox

Nox is a Latin word meaning night. It is the countercharm to Lumos and extinguishes the beam of light.

Incendio

Incendio comes from the Latin word ‘incendium‘ which means ‘causing a fire’. It produces flames.

Locomotor

Locomotor is a Latin word meaning moving from a place. It is used in Harry Potter to move objects.

Obliviate

Obliviate comes from the Latin word ‘oblivio meaning being forgotten. It is used to make the subject forget an event.

Homenum  Revelio

Let’s take each of these words separately. Homenum comes from the Latin word homo‘ which means human and revelio comes from the Latin word ‘revelare‘ which means reveal. In the books, this spell is used to detect hiding people.

Expelliarmus

Expelliarmus needs to be broken down into expelli and -armusExpelli comes from the Latin word ‘expellere‘ which means to drive out and armus comes from the Latin word ‘arma‘ which means weapons. In Harry Potter it is used to disarm your opponent.

So there you go! All you really need to be a wizard is a knowledge of Latin and a vivid imagination.