Nobel in Chemistry for an Evolutionary Revolution

https://phys.org/news/2017-10-nobel-chemistry-prize-major-award.html

The Nobel Prize awarded to Dr. Arnold, Dr. Smith, and Dr. Winters

Evolution, the process of gradual changes to genetic information in each generation over millions of years, proposed by Charles Darwin in the 19th century is being revolutionized by modern science. Unexpectedly, the revolution is driven not by evolutionary biologists or ecologists, but rather centered around the methodologies of chemists and enzymologists.

Accumulation of mutations is a slow and random process. However, scientists were able to harness the power of evolution to identify and select for specific mutations that improve the ability of molecules of interest. This year’s Nobel Prize in Chemistry was awarded to Dr. Frances Arnold “for the directed evolution of enzymes” and to Dr. George Smith and Dr. Gregory Winters “for the phage display of peptides and antibodies.”

Dr. Arnold was able to develop a methodology to enhance enzyme activity and give existing enzymes new functionality, a feat that was realized in unprecedented amount of time. She was able to accomplish this by simply using error prone PCR to cause mutations in enzymes and then selecting one with favorable ability compared to the many enzymes produced. Repeating the cycles hundreds of times enhancing the functionality of the enzyme each time, allowed her to develop P450 with novel function.

Dr. Smith was also able to apply the concepts of evolution by using bacteriophages, viruses that normally infect bacteria. Dr. Smith developed the process of phage display, a means to study protein-protein interactions by encoding genetic information into bacteriophages. By using E. coli cells infected with bacteriophages and then infecting with another virus, Dr. Smith was able to encode genetic information of a protein on to the viral coat of bacteriophages. This allowed the new protein to be displayed on the viral coat and able to be recognized with an antibody.

Dr. Winters then incorporated the antibody gene rather than a specific protein into the viral coat. This allowed him to scavenge for antibodies with a specific binding site via interactions with different antigens. Using a similar method to Dr. Arnold, he caused mutations in the antibody, and selected for the antibody with highest affinity to the antigen. The results were highly efficient antibodies and a mechanism that is used to produce 11 out the 15 most-sold drugs on the planet.

Peer edited by Rachel Battaglia.

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Stop Insulting Anglerfish Sex

http://www.photolib.noaa.gov/htmls/expl5923.htm

A deep sea anglerfish called a goosefish and is a member of the Lophiidae family – Sladenia remiger.  Image Credit: NOAA Okeanos Explorer Program, INDEX-SATAL 2010

You may have seen the anglerfish sex video floating around the Internet recently, with titles like “The worst sex in the world is anglerfish sex, and now there’s finally video.” While the video is worth a watch, I think most behavioral ecologist would beg to differ with the main assertion: there’s a lot of bad sex in the animal kingdom.

Why is anglerfish sex supposedly so terrible? A male anglerfish bites a females when he finds her, and then hangs onto her for the rest of his life, essentially turning into a living sac of sperm. But hey, at least he’s alive. In contrast, some species of male widow spiders somersault into the mouths of females as they mate, impaling themselves on their mates’ fangs. It sounds like an evolutionary enigma–why would an organism ever willingly sacrifice itself?–but turns out that that self-sacrifice can increase a male’s chances of fathering the female’s offspring.

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The female bed bug (the larger of the two) is traumatically inseminated by the male (bottom) through her abdomen.

Traumatic insemination” is another great example of not-so-great sex. In this case, bed bug females are the ones getting royally screwed, because traumatic insemination is a nice way of saying males stabbing females through the abdomen with their penises. The sperm then travels through the female’s hemolymph (the insect equivalent of blood), until reaching the ovaries and fertilizing the eggs. Males mate with all available females, because the last male to mate with any given female has the best chance of fathering her offspring. However, females who are subjected to these multiple matings pay a high cost: they have shortened lives and reduced reproductive output, because they have to allocate energy to healing the wounds and dealing with any resulting infections.

People often assume that two organisms mating with one another have the same “goals.” After all, both males and females are presumably invested in having as many healthy offspring as possible. But this is only true up to a certain point. Female widow spiders don’t need males to remain alive after mating, and in fact gain an advantage from eating the male (a ready source of nutrients that will help her with her next clutch!). In contrast, male widow spiders obviously benefit from not being eaten, and instead living to mate another day. Similarly, mating multiple times via traumatic insemination is costly to female bed bugs, who only need enough sperm to fertilize their eggs, while male bedbugs benefit from mating as many times as possible.

These are examples of what biologists call sexual conflict. While the source of conflict is obvious in the widow spiders’ and bed bugs’ cases, sexual conflict occurs anytime male and female genetic interests don’t align. In fact, the only time there is absolutely no potential for conflict is when males and females have exactly the same lifetime reproduction, so that each is equally invested in all of their shared offspring, with no opportunities for having offspring with other partners. In contrast, conflict can arise whenever one sex has the opportunity to improve their chances of having more, or better, offspring. This can happen in many different ways, such as: eating your partner, mating multiple times with the same partner, or even mating with multiple partners.

As a result, sexual conflict isn’t likely in anglerfish, at least those species which only have one mate for their entire lives. Although there are genera of anglerfish where females can have up to 8 males hanging off of her! So there’s potential for sexual conflict there, since the males will presumably compete to father her offspring and could do so in ways that are harmful to the female. However, anglerfish are incredibly hard to study because they generally occur in the deep sea. Frankly, male anglerfish have way more going for them than you might’ve ever thought–keep that in mind next time someone’s making fun of them.

 

Peer edited by Karen Setty.

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Cloned Monkeys: Another Human Creation

http://english.cas.cn/head/201801/t20180123_189488.shtml Image credited to Qiang Sun and Mu-ming Poo, Institute of Neuroscience of the Chinese Academy of Sciences

First cloned none-human primates: Zhong Zhong and Hua Hua (Image credited to Qiang Sun and Mu-ming Poo, Institute of Neuroscience of the Chinese Academy of Sciences)

Cloned primates are here! Over three decades have passed since the birth of Dolly, the sheep, scientists have now tackled cloning mammals that are even closer to us on the evolutionary tree: macaque monkeys. What does this mean for a society that witnesses dramatic changes day by day: computers are outperforming doctors in calling out heart abnormalities in patients; 3D-printed organs are bringing us one step closer to tissue restoration; genome sequencing has become an online product easily available for anyone curious about their ancestry, bodybuilding, or just simply wine tastes. Breakthroughs in science and technologies are so prevalent in our life that by now, we probably shouldn’t be surprised by any new discovery. Yet when the two cute, little, cloned monkeys were born, the whole world was, once again, shaken.

Published in Cell on January 24th, 2018, a study from a group of scientists in China reported their methods in generating two non-human primates that are genetically identical. To clone the two identical macaque monkeys, the scientists applied Somatic Cell Nuclear Transfer, the same method that generated Dolly in 1996. The key idea behind cloning is that a new organism, be it sheep or monkey, is generated without sexual reproduction. Asexual reproduction is not as uncommon as one would think, plenty of plants do so. For example, Bryophyllum shed plantlets from the edge of the leaves to produce new plants. Some insects, such as ants and bees, also exploit asexual reproduction to clone a huge working class army. Since asexual reproduction is essentially an organism duplicating itself, the offsprings are all genetically identical. Evolution, however, doesn’t favor asexual reproduction as identical offsprings don’t prevail in a fast changing environment. On the other hand, sexual reproduction combines different sperms and eggs to create diverse offsprings, of which some may survive. To combat challenges from the mother nature, higher organisms, such as mammals, almost exclusively reproduce sexually. This is why a cloned monkey, an anti-evolution human creation, is mind blowing.

https://commons.wikimedia.org/wiki/File:Kalanchoe_plantlets.JPG

The succulent, genus Kalanchoe, uses asexual reproduction to produce plantlets.

To clone mammals, scientists came up with the idea of transferring the nucleus of a somatic cell to an enucleated egg (an egg that lacks nucleus). Unlike  germ cells (sperm and eggs), somatic cells refer to any cells that don’t get passed onto the next generation. These cells have the full genome of an organism that is split equally in germ cells during sexual reproduction. Carrying half of the genome, sperm and egg need to fuse their genetic materials to make one viable embryo. Technically, the nucleus of a somatic cell holds all the genetic information an organism needs. Thus, by inserting the somatic cell nucleus into an egg, scientists could generate a functional embryo. But why not into a sperm? Evolution has trimmed mammalian sperm tremendously so that it can accomplish its only job better: swim faster to fertilize the egg. As a result, not much other than the sperm’s genetic information is incorporated into the fertilized egg and the embryo relies on the cellular machinery from the egg to finish development. Using this technology, the scientists generated over 300 “fertilized” embryos. Of these embryos, 260 were transferred to 63 surrogate mothers to finish developing. 28 surrogate mothers became pregnant, and from those pregnancies, only 2 healthy monkey babies were born. Although they were carried by different surrogate mothers, every single piece of their genetic code is the same as the the somatic nucleus provider, a real-life demonstration of primate-cloning. Followed by millions of people since their debut to the world, these two macaque superstars are the living samples of a revolutionary breakthrough in our science and technologies.

 

Despite the extremely low success rate, this technology erects another monument in the history of mankind’s creations. Carrying identical genetic information, cloned monkeys like these two can be a very powerful tool in biomedical research and diseases studies. Co-author Mu-ming Poo, director of the Chinese Academy of Sciences’ Institute of Neuroscience in Shanghai, said that these monkeys could be used to study complicated genetic diseases where environmental factors also play a significant role, such as Alzheimer’s and Parkinson’s diseases. While there are ethical concerns on this technology and its easy application to human cloning, it is worth noting that almost all human creations (explosives, GMO food, the internet, etc.) are double-sided swords. It is up to the hand that wields this sword to decide whether to do good or bad. It is wise to be cautious with the development of new technologies, but it’s also important not to constrain our creativity. After all, it is our creative minds that drive us toward creating a better life for everyone.

Peer edited by Cherise Glodowski.

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Bonnethead Shark: The Newest Veggie Lovers of the Sea

Vegetarian sharks.

If you love a cheesy sci-fi movie as much as I do, the word shark probably brings a few images to mind; swimmers rushing to shore, a huge, hungry, Great white, ready to devour anything in its sights. You may have even started humming the iconic Jaws theme. But you might be surprised to hear that off the big screen, not all sharks are out for blood. In fact, one shark prefers a leafy, green, salad.

We often think of sharks as strict meat eaters, but researchers at the University of California-Irvine are turning the meat hungry shark stereotype on its head with their (mostly) vegetarian Bonnethead sharks. The Bonnethead shark is a small type of hammerhead shark often found in warm, shallow waters of the Northern hemisphere. Bonnetheads get their name from their distinct shovel-like head shape.

https://commons.wikimedia.org/wiki/File:Sphyrna_tiburo_SI.jpg

The Bonnethead shark’s unique head shape distinguishes it from its hammerhead cousins.

 

Though distinct in appearance, the characteristic that makes the Bonnethead shark truly unique is its diet. Sharks are infamous meat-eaters. The Bonnethead, however, prefers its meat with a side of veggies. Studies on the diet of the Bonnethead began in 2007 when large amounts of seagrass were found in the stomach of a shark in the Gulf of Mexico. For many years, it was thought the seagrass was indigestible and eaten on accident while the sharks were hunting for shrimp, mollusks, and small fish in the seagrass ridden waters. Recent research now suggests Bonnethead sharks can digest the seagrass they eat and could use it as a source of nutrients.

As the first seagrass-eating shark be discovered, there are still many questions surrounding this veggie-loving shark. Does the Bonnethead eat seagrass on purpose? Or is it accidentally consumed while hunting for creatures on the ocean floor? Perhaps the most puzzling question is how  the Bonnetheads are able to digest seagrass? Because Bonnethead sharks have short intestines that are typical of a strict meat eater, scientists suspect bacteria living in the gut give the Bonnethead the ability to digest seagrass. More research is needed to discover which, if any, bacteria help the Bonnethead digest its dinner.

Although questions remain, one thing is certain; the Bonnethead shark is a unique and remarkable creature with much to teach their human neighbors about what constitutes a five-star meal under the sea.

Peer edited by Zhiyuan Liu.

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Tardigrades! The Super-animal of the Animal Kingdom

https://commons.wikimedia.org/wiki/File:Mikrofoto.de-Baertierchen5.jpg

Tardigrade (aka waterbear or moss piglet)

Tardigrades, also known as waterbears or moss piglets, are microscopic invertebrates that “resemble a cross between a caterpillar and a naked mole rat,” according to science writer, Jason Bittel. First discovered almost 250 years ago, there are now over 1,000 known species of tardigrade that can be found in almost every habitat throughout the world – from the depths of the ocean, to the tops of mountains, to your own backyard. As long as there is a little bit of moisture, you can find them. They are small and chubby, with most species being less than one millimeter in length. Their unique, usually transparent bodies have no specialized organs and four pairs of legs with claws at the end. Tardigrades can reproduce sexually or asexually via self fertilization. Like regular bears, Tardigrades eat a variety of foods, such as plant cells, animal cells and bacteria.

Despite being small, adorable microorganisms, tardigrades are fascinating creatures that have recently garnered the attention of scientists around their world due to their adaptability and resilience towards the most extreme environmental conditions. They have been observed to survive in a vacuum (an environment devoid air and matter) for up to eight days, for years to decades without water, temperatures ranging from under -200˚C to almost 100˚C, and heavy ionizing radiation. Tardigrades survive these conditions through a reversible mechanism known as desiccation (extreme drying), in which an organism loses most of the water in their body. In tardigrades, this can be as high as 97%. This is especially important in freezing temperatures, where water frozen into ice crystals can pierce and rupture the cells in the tardigrades’ body. During desiccation, the metabolic rate slows down to as low as 0.01% of normal function, allowing survival under the harshest of conditions for years.

https://commons.wikimedia.org/wiki/File%3AHypsibiusdujardini.jpg

Scanning Electron Microscopy image of a Tardigrade (Hypsibius dujardini)

In a 2016 Nature paper, scientists sought to answer the question of how a certain specie of tardigrade, Ramazzottius varieornatus, is so tolerant to extreme environmental conditions. They found an increase in several stress-related gene families such as superoxide dismutases (SODs). Most multicellular animals have less than ten SODs, however the study identified sixteen in this tardigrade specie. They also found an increased copy number of a gene known to play an important role in DNA double stranded breaks, MRE11. R. varieornatus had four copies of MRE11 while most other animals have only one.  Aside from having improved mechanisms of handling stress and DNA damage, scientists were able to identify waterbear-specific genes that seemed to explain tardigrades’ radiotolerance, or rather, resistance to radiation. The scientists were curious about whether this tardigrade-specific gene had any effect on DNA protection and radiotolerance in human cells. To their surprise, this gene, called DSUP for DNA damage suppressor, was able to decrease DNA damage in human cultured cells by 40% and decreased both double and single stranded DNA breaks.

At the University of North Carolina at Chapel Hill, Dr. Bob Goldstein studies animal development and cellular mapping during development in C. elegans and recently in tardigrades as well. He is also focusing on developing tardigrades into an new model system while studying their body development! His lab website has a section dedicated to tardigrades, with resources about them along with pictures and videos of tardigrades in motion.

The environmental resilience of tardigrades is incredible, making the tardigrade the super-animal of the animal kingdom (in my opinion). Who knows what other fascinating creatures we have yet to discover that may have characteristics as interesting and unbelievable as those of the tardigrade?

Peer edited by Nick Martinez.

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Little Farmers in the Animal Kingdom

Think of a farmer. Chances are, an image of an overall-wearing, pitchfork-wielding man just popped into your head. But humans are only one of a surprisingly large group of animals that cultivate their own food.

You might already know about leaf-cutter ants–some 47 species of ants in the New World that meticulously cut fresh vegetation into fragments that look far too big for them to hold. But they somehow manage to carry those leaf and flower cuttings back to their nests. This plant material is then used to feed the fungus that these ants depend on for food. Just like human farmers, the ants regularly plant, cultivate, and harvest their crop. However, rather than wheat or soybeans, the crop is a specific species of fungus. In fact, the relationship between the ant farmers and fungus is so complete that neither can survive without the other: the fungus can no longer  propagate itself without help from the ants, and the ants need the fungus for nutrition. Leaf-cutter ants are an extreme group of farming ants because they are so dependent on their fungal crop for survival, but about 240 ant species (collectively known as the attine ants) practice some form of fungus farming.

https://commons.wikimedia.org/wiki/File:Hitchiking_leafcutter_ant.jpg

A leaf-cutter ant carrying a leaf back to its nest, where the leaf will be used to grow fungi. Image from Wikimedia.

Farming isn’t limited to ants: some species of termites and ambrosia beetles (a type of weevil) are also known to grow fungus for food. These groups demonstrate some of what we think of as the most ‘advanced’ farming. They’re ‘advanced’ because they have evolved many adaptations specific to farming, such as specialized organs or behaviors, and they often can’t survive without farming. Because of this, and because scientists have long-known about the farming practices of these animals, these three groups are the most heavily studied non-human farmers. But focusing on just ants, termites, and beetles overlooks the fact that farming is likely evolutionarily beneficial for many organisms: when food is in short supply, being able to generate your own can be life saving.

Unsurprisingly then, once scientists started looking for evidence of farming in different organisms, they found it in snails, amoebas, and fish, among others. For example, the dusky farmerfish cultivates a specific species of algae. They do so in little ‘gardens,’ which they aggressively defend from other fish. When the farmerfish are experimentally removed from their gardens, all the algae is quickly eaten by other fish. The algae don’t seem to grow outside of these gardens, and the fish rely on this algae as a staple food, making this another relationship where both players need each other to survive.

But not all farming works this way: a different type of farming relationship was described in 2011 between an amoeba and a bacterium. The social amoeba, Dictyostelium discoideum, lives as single-celled organisms that spend their time eating bacteria. When environmental conditions get tough, the individual cells aggregate to form a ‘slug’ that crawls elsewhere more rapidly than the individual amoeba cells could have. Once in a better environment, the slug changes shape again. This time, it turns into a stalked fruiting body that releases spores. Each spore becomes a new single-celled amoeba. Some strains of this amoeba farm their bacteria: instead of eating all the available bacteria, they take some up and incorporate them into their fruiting bodies. When spores are released, the new amoebas are already carrying the bacteria with them, which they then use to seed their new environment with food–just like humans sowing their fields.

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D. dictyostelium in its stalked form, before releasing spores. These spores may or may not contain bacteria for farming, depending on the D. dictyostelium strain. Image from Wikimedia.

Not all Dictyostelium discoideum individuals demonstrate this farming behavior, which suggests that there could be downsides to farming. In this case, farming may be disadvantageous if the amoebas find themselves in a new environment that is already full of food. If this happens, the farming amoebas would have paid a cost by not eating all of the available food (and growing and reproducing) in their prior environment. In comparison, the non-farming amoebas wouldn’t have paid this same cost because they always eat all the food available to them. Because research on non-human farming has often focused on species that must farm to survive, the costly aspects of this behavior have not been extensively considered.

As scientists continue to explore the diversity of life on Earth, finding and characterizing new farming relationships can continue to give us insight into what this unique behavior can look like, and how it might vary in its evolution.

 

Additional readings:

Ants, termites, beetles: Mueller et al. 2005. The evolution of agriculture in insects. Annual Review of Ecology, Evolution, and Systematics 36:563-95.

Fish and algae: Hata H, Koto M. 2006. A novel obligate cultivation mutualism between damselfish and Polysiphonia algae. Biology Letters 2:593-6.

Amoebas: Brock et al. 2011. Primitive agriculture in a social amoeba. Nature 469:393-8. Brock et al. 2013. Social amoeba farmers carry defensive symbionts to protect and privatize their crops. Nature Communications 4:2385.

Peer edited by Paige Bommarito.

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How Evolution Gave Us Dragons

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Hiccup and his friendly dragon, Toothless, from How to Train Your Dragon. Credit: Brett Jordan

Whether our favorite characters are trying to train them, ride them, or simply escape from them, there is no denying the prevalence of dragons in popular culture. Dragon myths have existed for centuries in every civilization. In medieval Europe, uncharted parts of maps were supposedly marked with “Here be dragons” to designate danger and the unknown. In contrast, Chinese culture sees dragons as symbols of wisdom and benevolence. It is remarkable that such similar looking mythical creatures popped up separately in various cultures – and there may be an evolutionary explanation.

Dragons are depicted as large, reptilian-like creatures that can sometimes fly and breath fire. But why reptiles and why do they have to be so huge? It has often been speculated that some of the first discoveries of dinosaur or whales bones helped spark dragon mythology. People who discovered these huge bones, which resembled nothing they were familiar with, could have come up with a mythical creature like the dragon to explain them. However, it may not have been the curious mind that spawned dragons, but the fearful one.

In the book An Instinct for Dragons, anthropologist David E. Jones makes the case that a primal fear of predators, such as big cats and snakes, generated the dragon myth. Studies of Vervet monkeys demonstrate that they are especially fearful of three particular predators – lions, eagles, and snakes – and Vervet monkeys have specific cries they make when they spot these predators. Jones argues that this primal fear could have been passed along to humans through evolution. It is not hard to imagine our fearful ancestors combining the body of a snake with something as ferocious as a lion, and tacking on the ability to fly like an eagle, to get a dragon.

https://pixabay.com/en/animal-beast-creature-dragon-2029670/ (left) https://commons.wikimedia.org/wiki/File:Chinese_black_dragon.svg (right)

A primal fear of snakes, lions, and eagles may have inspired the creation of dragons in Western (left) and Eastern culture (right).

The hypothesis proposed by Jones is an interesting one, but has received criticism. It is nearly impossible to test and as powerful as evolution is, there is also the possibility that the myth was passed from culture to culture through storytelling. With cultures being so isolated for much of history, it would have been difficult for that to occur, but not impossible. And while their huge size would make it impossible for dragons to fly, it is not impossible to imagine that dragon myths will continue to mesmerize people for centuries to come.

Peer edited by Tom Gilliss.

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Fossils That Slumber in the Mountains and the Mud

Over 200 million years ago, a reptile, 11 feet long and 1500 pounds, was prowling about, likely feeling very pleased with himself. Not only did he have four crunchy creatures starting to digest in his stomach, but he had bitten another weakling in the neck and then crushed it under his left knee. Just at this moment of triumph, the reptile got stuck in the mud of ancient Jordan Lake, and slowly drowned.

Around the same time, by the seaside of what would one day become Italy, the forerunners to today’s oyster were nestling on the sea floor.

41 years ago, in 1976, Dr. Joe Carter obtained his PhD from Yale University and then drove down with his wife to start a new job at Chapel Hill’s geology department. He came as a sleuth for fossils. Ancient oysters, clams, mollusks, bivalves – Dr. Carter wanted to learn as much about them as he could.

credit: Mejs Hasan

Dr. Carter and one of his fossil replicas

For most of us, shells are just the violet-tinted, half-moon shaped spectacles that nip our feet at the beach.

But for Dr. Carter, these bivalves – and especially their fossils resurrected millions of years after they lived – are clues into evolutionary history.

In 1980, Dr. Carter took a trip to the mountains of northeastern Italy. There, he found an 80-year-old man who had been collecting Triassic fossils for decades – bivalves that lived 200 to 250 million years ago. The prospect of so many fossils was like coming upon a casket of jewels for Dr. Carter. The Italian man gave him a generous sampling of his fossil collection, and Dr. Carter fell to examining them.

“Well, this looks like an oyster,” Dr. Carter speculated, as he dwelt upon one of his fossils. Or was it? Oyster fossils dated back in time for 200 million years, beyond which they disappeared into the guarded slumber of the unwritten past. Scientists had assumed this marked the juncture at which oysters evolved, and as they cast about for a suitable ancestor, they decided upon scallops: both oysters and scallops have similar, non-pearly shells.

But perhaps the little Italian oyster told a whole new story. To investigate, Dr. Carter participated in a blatant case of disturbing the peace of the deceased. He took his Italian bivalve, sharpened his knife, and embarked on a long-delayed autopsy.

He dissected the defenseless fossil into impossibly tiny 150 micrometer slices. He examined each slice carefully under a microscope, then enlarged them on plastic drafting paper. Then, he had a “eureka” moment.

Today’s oysters are almost all calcite and non-pearly. But Dr. Carter’s ancient Triassic oyster had only a hint of calcite and it consisted mostly of mother-of-pearl. Could the mother-of-pearl oyster indicate that oysters evolved from “pearl oysters”, rather than from scallops?

credit: Mejs Hasan

Momentos from a long career

It was time to see if DNA could confirm the hint provided by the fossil record, a task given to Dr. Carter’s student, Kateri Hoekstra. She performed one of the first DNA analyses of living bivalves ever to focus on their evolutionary relationships. Just as the fossil record predicted, the DNA confirmed that the oyster from the Italian mountains, dug up after its rest of 221 million years, was a closer relative of pearl oysters than scallops.

Dr. Carter sent a letter to many natural history museums in Italy, asking them to find more of the mother-of-pearl oyster. But no one ever did. Still, Dr. Carter had fine pictures and drawings of the single known fossil. People started citing the fossil as UNC-13497b.

Such a clunky name would never do for the only mother-of-pearl oyster in the world, even if it did honor our great university. Dr. Carter finally christened it Nacrolopha carolae: Nacrolopha after the nacre (mother-of-pearl) in the Lopha-like oyster, and carolae after his wife, Carol Elizabeth.

This is the sweet side of invertebrate paleontology: a fine day in the Italian mountains, mother-of-pearl oysters, and suffusing the faint echoes of history with the name of your loved one.

But not everyone wants to give fossils their due attention.

The fossil record isn’t always perfect. For example, jellyfish rarely even leave fossils. For snails, the fossil record is misleading due to convergent evolution. The same features evolved in so many different snails that it’s hard to put things in order. You see the same shapes come up again and again.

As a result, many biologists have decided to send the fossil record packing. Since it doesn’t enlighten relationships for all groups of species, the idea that it might provide clues for a few is uncharted territory.

On the other side of the line-up, you have a handful of scientists, Dr. Carter, his former students, and his research colleagues among them. They are trying to convince the biologists that for some groups of species – especially bivalves – the fossil record is actually crucial.

It’s an uphill battle because, as Dr. Carter explains, the biologists have all the money. They are awash with government funds through the “Tree of Life” project that puts primary emphasis on DNA linkages between species.

credits: Mejs Hasan

Dr. Carter working in his lab.

Dr. Carter recognizes that DNA is a necessary tool. After all, it was Kateri’s DNA analysis that confirmed the origination of Nacrolopha carolae and modern oysters from pearl oysters. But it’s not the whole story. For example, DNA tells us that our closest relatives are the chimps. But that does not mean we evolved from them, or them from us! Fossils are the missing key that can shed light on the extinct creatures who filled in the evolutionary gaps.

Dr. Carter, along with David Campbell, his former student, now a professor at Gardner-Webb University, published a paper where they described how DNA and the fossil record can be used in symphony. Unfortunately, as Dr. Carter explains, “lots of people thought it was baloney.”

That reception is not stopping Dr. Carter. He and David Campbell are trying to publish a series of papers with examples of how DNA can give faulty evidence that the fossil record can correct. As Dr. Carter says, it will be interesting to see what the opposition says at that point.

Opposition aside, there’s one set of fossils that dazzles everyone – those of dinosaurs. Dr. Carter’s one foray into reptilian fossils happened by accident. Two of his students were studying a Durham quarry in 1994, when they came across the ankle bones of “a weird new guy”. It was the same unfortunate creature that, having filled his stomach with four prey, sank into a mudhole of ancient Jordan Lake and drowned just at its very moment of triumph. Digging it up, Dr. Carter and his students found hundreds of bones. Once cleaned and reassembled, it turned out to be a reptile shaped very much like a dinosaur, but not quite.

Dinosaurs roamed about on tiptoe, but this reptile’s foot walked on both toes and heels, like humans do. It was the best-preserved skeleton of this group of reptiles ever found. Dr. Carter toured museums in Europe and the US to make sure the reptile had not been named before.

Just thereafter, Karin Peyer walked into Dr. Carter’s office. She had an undergraduate degree in paleontology, a husband starting graduate school at UNC, and time on her hands. She asked: do you need any help?

“Boy, did you come at the right time!” Dr. Carter greeted her. Karin worked with Dr. Carter and experts from the Smithsonian Institution to formally describe and name the find.

They called it Postosuchus alisonae – alisonae a tribute to a friend of Dr. Carter’s who was dying of cancer at that time.

*******************

It was December 2015. In Dr. Carter’s large dim lab, filmy sheets of plastic drafting paper were ruffling in a soft breeze from the open window looking out on a hillside over Columbia Street. Sickle-shaped knives were stacked here and there, beside replicas of treasure from King Tut’s tomb. In between sectioning and sketching an ancient bivalve called Modiolopsis, Dr. Carter was packing.

credits: Mejs Hasan

Dr. Carter at his retirement party

He was retiring after 39 years. In practice, that merely means that Dr. Carter can now avoid going to faculty meetings. Otherwise, he can still serve on graduate student committees; he is coordinating the revisions of bivalves in the Treatise of Invertebrate Paleontology. He still has fossils to section and examine, and biologists to convince of the worth of the fossil record.

The only difference is, when Dr. Carter began his professorial work, it was just him and his wife, a young daughter and a baby boy. Now his daughter is 45 years old and his son is 39, and they both have their own families that Dr. Carter will be spending a lot of time with. It’s amazing what changes four decades can bring. But perhaps it’s easier to be philosophical and surrender to what’s ahead when you hold in your hands an oyster that lived 221 million years ago.

Peer edited by Lindsay Walton and Alison Earley.

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A Dinosaur “Tail”

Cortney CavanaughWhat happens when scientists get their hands on the remains of a dinosaur encased in ancient amber? Fortunately, life doesn’t imitate art to the extent to which we should be concerned about the potential pitfalls associated with an amusement park filled with revived, prehistoric beasts. And while you shouldn’t save any vacation time for a trip to Jurassic Park in the near future, paleontologists are excited to celebrate the findings of a well-preserved, feathered dinosaur tail published last month in Current Biology.

The mines of Myanmar are a longstanding source of the precious “gemstone” that is known as Burmese amber. While miners were searching for their own fossils (technically amber is fossilized tree resin) they came across a sample, smaller than a credit card and weighing about as much as one, that contained more than the usual bits of insects and foliage. This amber contained a portion of a tail, belonging to a juvenile dinosaur, which was covered in feathers. The fossil was obtained in 2015, directly from the miners, by paleontologist Lida Xing who hoped to learn more about the structure of the plumage. Evidence of feathered dinosaurs, which were distinct from the birds they coexisted with, was first discovered just before the turn of the 21st century. Despite their known existence, little has been discovered in terms of the evolution of the dinosaurs’ feathered coating. This finding, in particular, has given paleontologists a glimpse into the early differentiation between bird and dinosaur feathers.

Cortney Cavanaugh

Maybe one day a complete dinosaur encased in amber will be on display at a museum for all to see!

Xing and his fellow researchers proposed that the specimen belonged to a group of two-legged dinosaurs known as coelurosaurs. The well-preserved sample was determined to be about 100 million years old, placing the species’ existence in the mid-Cretaceous period. Researchers were also able to conclude that the fragment belonged to a young dinosaur and that it was likely a portion of a much longer tail. Based on the structure of the preserved feathers, it was determined that the dinosaur was probably incapable of flight and that the feathers were more of an ornamental feature than a functional one. This sample is considered to be especially unique and precious as it is the first of its kind to contain feathers that are affixed to soft tissue, as well as bones, which are also intact. Once all of the possible data and information is divulged from the sample, Xing hopes to return the sample to its native Myanmar due to its value as a unique, fossilized specimen.

While the reanimation of dinosaurs for human amusement remains a tale of science fiction, the scientific community will certainly benefit greatly from the knowledge that can be obtained by studying these rare remains. Perhaps the ultimate goal for paleontologists will be to uncover an amber fragment that bears the remains of a complete dinosaur just waiting to reveal its secrets!  

Peer edited by Manisit Das.

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