In biology, the first (usually) example of a given species that is scientifically described is the holotype, and all other examples of the species are determined to be members of that species based on their similarities to the holotype.
This is true whether that first specimen is a captured animal that’s fully preserved in a museum to this day, or a single fossil tooth that was lost when a museum burned down.
In palentology, a holotype is sometimes extremely sparse, because it was the first time we found a fossil that was clearly not anything we already know but which was also very fragmentary. Then 50 years later we might find another more complete example and we use that going forward, calling it a “neotype”.
My question is, does this also happen with extant animals? I assume it does if the original specimen is lost; but have we ever realized that the first described specimen was actually extremely unusual for its type, being way bigger or smaller or a different color or being assymetrical or anything like that?
I can find some examples that are similar to what I’m thinking of, but not quite right. For example, the Nechisar Nightjar was a bird found as a corpse in an Ethiopian national park; it was distinct from all known nightjars based on the size, pattern on the wing, and some other factors; but genetic study determined that it was a hybrid between two nightjar species.
The scenario I’m envisioning would be something like, a spotted nightjar is discovered and described, then afterwards a non spotted nightjar is discovered and no spotted specimens are ever found again, and eventually we find out through genetic analysis that the original spotted specimen just happened to be a weird mutation of the common species.
A holotype is, if I am understanding correctly, the sample used as illustration by the original author? Not based on any biological definition of “species” … which itself is very fuzzy. Correct?
It’s the individual that the scientist who described the species was working off of when they did so. Ideally, we would know exactly which specimen that was, and still have it in a museum somewhere so it can be reexamined as often as needed in the future.
At least, that’s how we do things today. Obviously for most of your common species - the sorts that Linnaeus and his contemporaries developed our classification system with - that isn’t always available. We don’t know which Panthera leo specimen Linnaeus was looking at when he described the lion, and there’s good reason to think it was a (now extinct) Barbary lion. And in fact, in 1924 to bring the Panthera leo species up to par with latter described species, scientists did designate an individual dead lion as the type specimen. So when we try to determine if an Asiatic lion or a South/East African lion is the same (sub)species as the “normal” lion, we compare them to the type specimen. Same thing with fossil or subfossil remains from ancient lions.
For animals we found more recently, like the Saola, the type specimen is a skull preserved with horns, because those remains were the first instance of saola that became known to science; the same expedition found live animals later that year, but the material they had on hand at the time that they described the species was just the skull and horns, and this was enough to tell them that this was clearly a new species - so it’s sufficient as a holotype.
Something that happens with dinosaurs is, we find a leg bone that clearly belongs to a theropod dinosaur that’s three times the size of anything known from that area and with a clear difference from other known carnivores; so we name a new species (let’s call it Babalesaurus). Eventually we find a more complete skeleton that seems to match, so we assign it to the same species. And then we find another complete skeleton that also matches the leg bone but is clearly a different species than the first complete skeleton. So we closely analyze all the bones and realize that the new complete skeleton does indeed match and so can be assigned to Babalesaurus; but the earlier complete skeleton is in fact subtly different. So the scientists who figured that out get to name a new species, using the first complete skeleton as the holotype - maybe they call it DSeidsaurus - and the second skeleton is assigned to Babalesaurus.
Hence my confusion. I had understood that as fuzzy as the species concept may be the current definitions are based more on genetic relatedness and interbreeding ability. Less on what they look like. “Holotype” and “neotype” are still in use? They come off as quaint or archaic to my read. But not in the field so may just be my ignorance.
I’m not sure I understand what genetics have to do with the concept of holotype? Or rather, how these are contradictory ideas?
It’s true that in the past a species was defined based on a list of physical characteristics and today it’s based on genetic interrelatedness. But you’re still going to have a specific individual who bears the name of the species as the standard to compare to, no?
Note that whether you’re looking at it morphologically or genetically you’re still doing things like population studies. We see this, again, with dinosaurs - we might measure the exact ratio of length to width in femurs from a given species in order to show that there are distinct clusters in the robust and gracile ranges that are not correlated to sex, and thus argue for two separate species; just as we might do a genetic study on a population and determine that there are two clusters that don’t breed much. Just because you have a holotype doesn’t mean you aren’t also studying the species as a population as well.
I am not a paleontologist, but one of my favorite books as a kid was Search for a Living Fossil. And in that recount, the first coelacanth did not have spots on its skin, and when a second coelacanth was found, it did, and for a brief period was allocated a separate species designation, which was later cancelled when subsequent coelacanths showed a range of coloration patterns.
Does that fit into the inquiry?
ETA: hmm, some Googling appears to indicate that this was reversed and the science community came to regard them as separate species after all.
I’m not sure if I’ve ever heard of such a case and I used to be into taxonomy a bit, though no expert. It’s certainly possible, because stranger things have happened in museum science. But I haven’t heard of any in that exact category. If it did, I might bet on some obscure arthropod being most likely (and easiest to elude discovery).
If such a critter did exist, especially in the good old days, it likely would just be re-assigned it’s own species name and a holotype for that single critter based on distinct coloration/gross morphology and which would then be presumed extinct. Museums are almost always tight on cash and recovery of genetic material from a random 250 year-old taxidermy specimen living in a drawer is not going to be a high priority. It would almost certainly languish until some curator or outside grad student doing a very specific study on closely related taxa came wandering through with an outside research grant. Which means discovering such an oddity is a statistical long-shot. Might happen eventually, but what eventually means in that context is anyone’s guess.
Holotypes are reassigned and museum specimens synonymized all the time. Historically, anyway. Especially as fallout from the great boom of the 19th century gentleman naturalists, when an awful lot of animals ended up being described from dead specimens collected on expeditions. Which could lead to some weird screw-ups.
Over in the ‘Today in nature I saw’ thread I posted and commented sarcastically on a series of photos I took of a pair of ring-necked ducks. The glossy, reflective ring around the neck of the adult males is apparently super-obvious and stands out when when you have a dead duck in your hands. In the field it is usually virtually impossible to see unless the light and angle is dead perfect. Leading to generations of inexperienced birders blinking in confusion as they try to find a hidden ring.
Linnaeus himself is the holotype for Homo sapiens, and considering that he was a well-educated upper class Swede, he was probably not the typical specimen of the global human population, neither in his time nor today.