As Species Decline, So Do the Scientists Who Name Them 76
tcd004 (134130) writes "Few sciences are more romantic than taxonomy. Imagine Darwin, perched over a nest of newly-discovered birds in the Galapagos, sketching away with a charcoal in his immortal journals. Yet Taxonomy is a dying science. DNA barcoding, which can identify species from tiny fragments of organic material, and other genetic sciences are pulling students away from the classical studies of anatomy and species classifications. As the biodiversity crisis wipes undiscovered species off the planet, so to go the scientists who count them."
It's not dead, it's evolving (Score:5, Insightful)
DNA isn't pulling people away from taxonomy so much as replacing it with a vastly superior system. Classical taxonomy is kind of like classical mechanics. It's fine for most purposes, but it's not "complete" and its answers range from slightly inaccurate to flat out wrong depending on the question.
We no longer have to arbitrarily decide "ok, this is a new species because it's different in this way" we can now look at DNA and see exactly how it differs, what it's closest to, who its ancestors are, when it split, and so on. Names are inaccurate representations for humans to use. With DNA, the term "species" itself becomes somewhat irrelevant because we now know the system of species and genetics is much more fluid than that.
So what? (Score:5, Insightful)
If DNA sequencing means taxonomy is now straightforward, then it's good students are switching to other fields. The goal of science is to solve problems, not to ossify. In this case, while taxonomy may cease to be a significant research field, morphology (understanding the structure and evolution of plants and animals) is surely going to continue. The people doing it will simply not be called "taxonomists" anymore.
During the 80s and 90s there were different projects trying to determine the cosmological parameters (mass density, curvature, cosmological constant, Hubble constant, etc). Then WMAP [wikipedia.org] was launched in 2001, and by 2006 (release of 3-year data) the previous techniques were obsolete. Do you think many students in 2001 started working on the old techniques? Should they have? But we haven't lost interest in the cosmological parameters.
Re:It's not dead, it's evolving (Score:5, Insightful)
Exactly right, but it's worth warning there are still a lot of issues with the subject, not least the fact that in changing the way taxonomy is done there is confusion about what taxonomy is meant to actually achieve.
On one hand you have people who want easy names for things, so they can refer to them in conversation, or write books. Hey look at this "Blah blah" plant and so on.
On the other you have the needs of science - the need to be able to explicitly define a cut off point to say this is a different species, a different genus, a different family or whatever.
Historically taxonomy has had problems without DNA analysis because it's been based pretty much entirely on how a plant looks, it's features. If Plant A is a small fat round green cactus with 1 inch spines and small purple flowers and Plant B has the same then they must be the same species, or at least the same genus. This sounds well and good, but the advent of DNA analysis sometimes shows that plant A and plant B are in fact extremely genetically distinct and aren't closely related at all. So why did they look the same? Convergent evolution - if the two plant populations were 200 miles apart directly north-south to each other and the species that pollinates them likes small purple flowers then they've simply evolved the same traits through natural selection because of that pollinator. Meanwhile another plant 100 miles to the East of plant A may be a large tall thin cactus with a blue powdery coat and large white flowers but actually ends up being more genetically similar to the point it's in the same genus as plant A - it looks completely different because although it shares ancestry it's on the path of a completely different pollinator that likes tall blue plants with massive white flowers. The net result is that plants that are genetically close are not identified as such based on visual inspection, whilst those that aren't close are lumped together when they shouldn't be using classical taxonomy. This is why the AC above says classic taxonomy is sometimes outright wrong. Looks don't tell us anything like the sort of picture we need to know - without being able to track the growth and evolution of species through time we simply do not know the ancestry, so until the arrival of DNA taxonomy was a fundamentally flawed science.
So it seems like DNA solves everything right? Wrong. The problem we have now is that it's still arbitrary as to where you decide the cut off, how different does a subject have to be to be a distinct species from another subject? If their DNA varies by 0.00000000001% we can probably agree they're closely related enough to be the same species, but what about a 0.1% difference? what about a 1% difference? When we figure that out we then have to decide the boundaries for genus, for families, and also in the other direction for subspecies and so forth. Right now there is no fixed figure so it's still arbitrary - one taxonomist is separating species based on a 0.1% difference, and another is doing it on a 0.15% difference. This means we still have nonsense arguments about what genus a species belongs in or whatever - nonsense because it's completely down to personal opinion, and that's subjective.
The problem is that if we do do something objective and say right, well, the cut off points are 0.1% for species, 1% for genus and so on we end up with situations where subjects are lumped together in a manner that are inconvenient for the trade world, and for gardeners "Oh I've always called it that, I'm not changing the name, they need the same growing conditions so I'm going to treat them like they always used to be named" - sometimes the objective system can result in surprising classifications that are inconvenient for non-scientific users and so they refuse to adopt them.
Which takes us back to the original question - what is the point in taxonomy? From there we have to ask things like who does it exist to serve? What are it's goals? Does science even need it? would scientists be better off moving to a w
Re:It's not dead, it's evolving (Score:5, Insightful)
DNA isn't pulling people away from taxonomy so much as replacing it with a vastly superior system. Classical taxonomy is kind of like classical mechanics. It's fine for most purposes, but it's not "complete" and its answers range from slightly inaccurate to flat out wrong depending on the question.
We no longer have to arbitrarily decide "ok, this is a new species because it's different in this way" we can now look at DNA and see exactly how it differs, what it's closest to, who its ancestors are, when it split, and so on. Names are inaccurate representations for humans to use. With DNA, the term "species" itself becomes somewhat irrelevant because we now know the system of species and genetics is much more fluid than that.
I'm not so sure Taxonomy has been replaced, it's just gotten a whole new and better tool and I suppose you could say the geneticists have kind of taken it over. In anthropology ancient DNA extraction where classification into species was done using skeletal morphology, DNA is likely to cause a whole lot of re-arrangement of the taxonomic classifications. When Svante Pääbo found Neanderthal DNA in modern humans he effectively threw the scientific equivalent of a hand grenade into the comfortably organized world of anthropology. His discovery shattered a widely accepted axiom and left a whole lot of people red-faced who'd been postulating that modern human admixture with archaic hominids was unlikely to the point of it being impossible. Technically modern non-African people belong to both the species H. Sapiens and H. Neanderthalensis, so the borderlines between species have all of a sudden become much more fuzzy thanks to geneticists. A really interesting recent development is that geneticists have found traces of extinct hominid populations that are only known from DNA analysis of living humans, not from discovered remains. Africans for example are now know to have interbred with archaic hominid populations but no physical specimens, i.e. skeletal samples of these archaic populations have ever been found so in that sense Africans aren't pure H. Sapients either. So we now have palaeontologist/archaeologists out in the field searching for physical remains of these 'shadow' or 'ghost' populations which has turned the normal practice in their field completely on it's head where you first found the bones and then took them to the lab for (DNA and other) analysis. As we get better at extracting DNA from ancient remains it will completely upend a lot of what we thought we knew about the mechanism of evolution.
Re:It's not dead, it's evolving (Score:5, Insightful)
"That's true. People scoff at the older taxonomic groupings from before we had molecular evidence, but actually I'm often surprised at how similar new phylogenies are to huge chunks of the old taxonomies."
I'm sure that depends on the families and genus in question, because certainly for Cactaceae it's made a complete mockery of previous taxonomic definitions.
"(i.e. cites the taxnomic publication which specifies what they mean when they use the name)."
Amusingly I tried to help a botanist do exactly this, we couldn't because although we found a snippet on Google Books of the original reference for the name, we couldn't see the whole thing because it unfortunately fell under the specific set of restrictions that meant it wont be out of copyright until about 2021, despite the fact it went out of print in about 1926 and the author died in about 1953 or something. I thought this was a fantastic example of how absurdly long copyright laws prevent scientific progress.