What’s in a Name?

Part Two: How’s Your Latin?

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The awesomely named Obamadon gracilis.  Image: Reuters

What do Barack Obama, Marco Polo, and the band Green Day have in common? They all have at least one organism named after them. Obama has several, including a bird called Nystalus obamai and an extinct reptile named Obamadon gracilis. Green Day’s honorary organism is the plant Macrocarpaea dies-viridis, “dies-viridis” being Latin for “green day.” Many scientists also have species named after them, usually as recognition for their contributions to a field. My own PhD advisor, Dr. Anne Bruneau, has a genus of legumes, Annea, named after her for her work in legume systematics.

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“Pear-leaved Pear”   Photo via Wikimedia Commons

Scientific names, which are colloquially called Latin names, but which often draw from Greek as well, consist of two parts: the genus, and the specific epithet. The two parts together are called the species. Though many well-known scientists, celebrities, and other note-worthies do have species named after them, most specific epithets are descriptive of some element of the organism or its life cycle. Many of these are useful descriptions, such as the (not so bald) bald eagle, whose scientific name is the more accurate Haliaeetus leucocephalus, which translates to “white-headed sea eagle.” (See here for some more interesting examples.) A few are just botanists being hilariously lazy with names, as in the case of Pyrus pyrifolia, the Asian pear, whose name translates as “pear-leaved pear.” So we know that this pear tree has leaves like those of pear trees. Great.

In contrast to common names, discussed in our last post, Latin names are much less changeable over time, and do not have local variants. Soybeans are known to scientists as Glycine max all over the world, and this provides a common understanding for researchers who do not speak the same language. Latin is a good base language for scientific description because it’s a dead language, and so its usage and meanings don’t shift over time the way living languages do. Until recently, all new plant species had to be officially described in Latin in order to be recognized. Increasingly now, though, descriptions in only English are being accepted. Whether this is a good idea remains to be seen, since English usage may shift enough over the years to make today’s descriptions inaccurate in a few centuries’ time.

This isn’t to say that scientific names don’t change at all. Because scientific names are based in organisms’ evolutionary relationships to one another (with very closely related species sharing a genus, for example), if our understanding of those relationships changes, the name must change, too. Sometimes, this causes controversy. The most contentious such case in the botanical world has been the recent splitting of the genus Acacia.

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The tree formerly known as Acacia. Via: Swahili Modern

Acacia is/was a large genus of legumes found primarily in Africa and Australia (discussed previously on this blog for their cool symbiosis with ants). In Africa, where the genus was first created and described, the tree is iconic. The image of the short, flat-topped tree against a savanna sunset, perhaps accompanied by the silhouette of a giraffe or elephant, is a visual shorthand for southern Africa in the popular imagination, and has been used in many tourism campaigns. The vast majority of species in the genus, however, are found in Australia, where they are known as wattles. When it became apparent that these sub-groups needed to be split into two different genera, one or the other was going to have to give up the name. A motion was put forth at the International Botanical Congress (IBC) in Vienna in 2005 to have the Australian species retain the name Acacia, because fewer total species would have to be renamed that way. Many African botanists and those with a stake in the acacias of Africa objected. After all, African acacias were the original acacias. The motion was passed, however, then challenged and upheld again at the next IBC in Melbourne in 2011. (As a PhD student in legume biology at the time, I recall people having firm and passionate opinions on this subject, which was a regular topic of debate at conferences.) It is possible it will come up again at this year’s IBC in China. Failing a major turnaround, though, the 80 or so African acacias are now known as Vachellia, while the over one thousand species of Australian acacias continue to be known as Acacia.

The point of this story is, though Latin names may seem unchanging and of little importance other than a means of cataloguing species, they are sometimes both a topic of lively debate and an adaptable reflection of our scientific understanding of the world.

Do you have a favourite weird or interesting Latin species name? Make a comment and let me know!

What’s in a Name?

Part One: Common vs. Scientific Names

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When I was a kid growing up on a farm in southwestern Ontario, sumac seemed to be everywhere, with its long, spindly stems, big, spreading compound leaves, and fuzzy red berries. I always found the plant beautiful, and had heard that First Nations people used the berries in a refreshing drink that tastes like lemonade (which is true… here’s a simple recipe). But often, we kids were warned by adults that this was “poison sumac,” not to be touched because it would give us itchy, burning rashes, like poison ivy did. In fact, plenty of people would cut down any nascent stands to prevent this menace from spreading. We were taught to fear the stuff.

 

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THIS is the stuff you need to look out for. Via The Digital Atlas of the Virginia Flora

It was many years later before I learned that the red-berried sumacs I grew up with were not only harmless, but were also not closely related to the poisonous plant being referred to, which, as it turns out, has white berries and quite different leaves. Scientifically speaking, our innocent shrub is Rhus typhina, the staghorn sumac, while the rash-inducing plant is called Toxicodendron vernix. Not even in the same genus. Cautious parents were simply being confused by the similarity of the common names.

 

This story illustrates one of the ironies of common names for plants (and animals). Though they’re the way nearly everyone thinks of and discusses species, they’re without a doubt the most likely to confuse. Unlike scientific (Latin) names, which each describe a single species and are, for the most part, unchanging, a single common name can describe more than one species, can fall in and out of use over time, and may only be used locally. Also important to note is that Latin names are based on the taxonomy, or relatedness, of the species, while common names are usually based on either appearance, usage, or history.

 

This isn’t to say that common names aren’t valuable. Because common names describe what a plant looks like or how it is used, they can convey pertinent information. The common names of plants are also sometimes an important link to the culture that originally discovered and used the species, as in North America, where native plants all have names in the local languages of First Nations people. It seems to me, although I have no hard evidence to back it up, that these original names are now more often being used to form the Latin name of newly described species, giving a nod to the people who named it first, or from whose territory it came.

 

One high profile case of this in the animal world is Tiktaalik roseae, an extinct creature which is thought to be a transitional form (“missing link”) between fish and tetrapods. The fossil was discovered on Ellesmere Island in the Canadian territory of Nunavut, and the local Inuktitut word “tiktaalik”, which refers to a type of fish, was chosen to honour its origin.

 

But back to plants… Unlike staghorn sumac and poison sumac, which are at least in the same family of plants (albeit not closely related within that family), sometimes very distinct species of plants can end up with the same common name through various quirks of history. Take black pepper and bell or chili peppers. Black pepper comes from the genus Piper, and is native to India, while hot and sweet peppers are part of the genus Capsicum. Botanically, the two are quite distantly related. So why do they have the same name? Black pepper, which bore the name first, has been in use since ancient times and was once very highly valued. The confusion came about, it would seem, when Columbus visited the New World and, finding a fruit which could be dried, crushed, and added to food to give it a sharp spiciness, referred to it as “pepper” as well.

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A black peppercorn. Easy to confuse with a chili pepper, I guess? Via: Wikimedia Commons

 

Another interesting, historically-based case is that of corn and maize. In English-speaking North America, corn refers to a single plant, Zea mays. In Britain and some other parts of the Commonwealth, however, “corn” is used to indicate whatever grain is primarily eaten in a given locale. Thus, Zea mays was referred to as “Indian corn” because it was consumed by native North Americans. Over time, this got shortened to just “corn”, and became synonymous with only one species. Outside of Canada and the United States, the plant is referred to as maize, which is based on the original indigenous word for the plant. In fact, in scientific circles, the plant tends to be called maize even here in North America, to be more exact and avoid confusion.

 

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Not Spanish, not a moss. Via: Wikimedia Commons

And finally, for complete misinformation caused by a common name, you can’t beat Spanish moss. That wonderful gothic stuff you see draped over trees in the American South? That is neither Spanish, nor a moss. It is Tillandsia usneoides, a member of the Bromeliaceae, or pineapple family, and is native only to the New World.

 

And that wraps up my very brief roundup of confusing common names and why they should be approached with caution. In part two, I’ll discuss Latin names, how they work, and why they aren’t always stable and unchanging, either.

 

There are SO many more interesting and baffling common names out there. If you know of a good one, let me know in the comments!

 

*Header image via the University of Guelph Arboretum

Forever Young

How Evolution Made Baby-faced Humans & Adorable Dogs

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Who among us hasn’t looked at the big round eyes of a child or a puppy gazing up at us and wished that they’d always stay young and cute like that? You might be surprised to know that this wish has already been partially granted. Both you as an adult and your full-grown dog are examples of what’s referred to in developmental biology as paedomorphosis (“pee-doh-mor-fo-sis”), or the retention of juvenile traits into adulthood. Compared to closely related and ancestral species, both humans and dogs look a bit like overgrown children. There are a number of interesting reasons this can happen. Let’s start with dogs.

When dogs were domesticated, humans began to breed them with an eye to minimizing the aggression that naturally exists in wolves. Dogs that retained the puppy-like quality of being unaggressive and playful were preferentially bred. This caused certain other traits associated with juvenile wolves to appear, including shorter snouts, wider heads, bigger eyes, floppy ears, and tail wagging. (For anyone who’s interested in a technical explanation of how traits can be linked like this, here’s a primer on linkage disequilibrium from Discover. It’s a slightly tricky, but very interesting concept.) All of these are seen in young wolves, but disappear as the animal matures. Domesticated dogs, however, will retain these characteristics throughout their lives. What began as a mere by-product of wanting non-aggressive dogs has now been reinforced for its own sake, however. We love dogs that look cute and puppy-like, and are now breeding for that very trait, which can cause it to be carried to extremes, as in breeds such as the Cavalier King Charles spaniel, leading to breed-wide health problems.

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An undeniably cute Cavalier King Charles spaniel, bred for your enjoyment. (Via Wikimedia Commons)

Foxes, another type of wild dog, have been experimentally domesticated by scientists interested in the genetics of domestication. Here, too, as the foxes are bred over numerous generations to be friendlier and less aggressive, individuals with floppy ears and wagging tails – traits not usually seen in adult foxes – are beginning to appear.

But I mentioned this happening in humans, too, didn’t I? Well, similarly to how dogs resemble juvenile versions of their closest wild relative, humans bear a certain resemblance to juvenile chimpanzees. Like young apes, we possess flat faces with small jaws, sparse body hair, and relatively short arms. Scientists aren’t entirely sure what caused paedomorphosis in humans, but there are a couple of interesting theories. One is that, because our brains are best able to learn new skills prior to maturity (you can’t teach an old ape new tricks, I guess), delayed maturity, and the suite of traits that come with it, allowed greater learning and was therefore favoured by evolution. Another possibility has to do with the fact that juvenile traits – the same ones that make babies seem so cute and cuddly – have been shown to elicit more helping behaviour from others. So the more subtly “baby-like” a person looks, the more help and altruistic behaviour they’re likely to get from those around them. Since this kind of help can contribute to survival, it became selected for.

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You and your dog, essentially. (Via The Chive)

Of course, dogs and humans aren’t the only animals to exhibit paedomorphosis. In nature, the phenomenon is usually linked to the availability of food or other resources. Interestingly, both abundance and scarcity can be the cause. Aphids, for example, are a small insect that sucks sap out of plants as a food source. Under competitive conditions in which food is scarce, the insects possess wings and are able to travel in search of new food sources. When food is abundant, however, travel is unnecessary and wingless young are produced which grow into adulthood still resembling juveniles. Paedomorphosis is here induced by abundant food. Conversely, in some salamanders, it is brought on by a lack of food. Northwestern salamanders are typically amphibious as juveniles and terrestrial as adults, having lost their gills. In high elevations where the climate is cooler and a meal is harder to come by, many of these salamanders remain amphibious, keeping their gills throughout their lives because aquatic environments represent a greater chance for survival. In one salamander species, the axolotl (which we’ve discussed on this blog before), metamorphosis has been lost completely, leaving them fully aquatic and looking more like weird leggy fish than true salamanders.

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An axolotl living the young life. (Via Wikimedia Commons)

So paedomorphosis, this strange phenomenon of retaining juvenile traits into adulthood, can be induced by a variety of factors, but it’s a nice demonstration of the plasticity of developmental programs in living creatures. Maturation isn’t always a simple trip from point A to point B in a set amount of time. There are many, many genes at play, and if nature can tweak some of them for a better outcome, evolution will ensure that the change sticks around.

Sources

*Header image by: Ephert – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=39752841