Taxonomy, Cladistics, and iNaturalist

Nature Talk
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Introduction:
As we naturalists all experience first hand everyday, our planet has an immense biodiversity. With the more conservative estimates starting at roughly 3 million species and that number going up to >100 million according to other sources¹ (Tangley, 1998), it becomes necessary to somehow classify all these organisms and naming them. There are various approaches to creating such classifications, emphasising different aspects. A lot of people have very strong opinions about it, and different classifications may be more or less useful depending on what you want to do.

Evolution as the Central Theory of Biology:
Evolution is the key to understanding life. It is to biology what Albert Einstein’s Theory of Relativity and Newton’s Laws of Thermodynamics are to physics and it holds enormous explanatory power. "Nothing in Biology Makes Sense Except in the Light of Evolution“² (Dobzhansky, 1973). Evolution alone can provide a satisfactory answer for how life formed from dead matter, and how we got from that first lone simple cell (LUCA, Last Universal Common Ancestor) to the diversity in shape and colour, function and behaviour we see today.
It offers us something more, however. Everything bears the signs of its history, whether that is the way the leaning tower of Pisa was built, the scars and wrinkles on a person, or the „evolutionary path“ an organism has taken. Species aren’t arbitrarily different from each other. In addition to the constraints imposed by the environment, species are also limited by the constraints imposed by their „lineage“. It leads to a gradually declining similarity between organisms the more distantly they are related. And this is an excellent basis for a classification of organisms.

Cladistsics/Phylogeny Is the Best Way to Classify Organisms
Creating such a classification is the central aim of cladistics/phylogeny (they aren’t the same, but for this post the differences do not matter, so I will use these terms interchangeably). Cladistics knows 2 central „units“ into which organisms can be grouped: species and monophylum.
The debate surrounding the definition of „species“ would probably warrant its own post, but for now let’s define a species as „a collection of organisms which under natural conditions can reproduce produce fertile offspring“.
A monophylum is any branch of any size and age on a phylogenetic tree which groups together no more and no less than all descendants of the root species of that branch.
The biggest strength of cladistics is its objectivity (limited only by the gaps in our knowledge). It is not just a classification, it is a model of evolutionary history, and therefore, assuming humans were omniscient, every grouping of organisms is based on reality.
But of course, an as-accurate-as-possible model of something as complex and diverse as life, has to be somewhat complex itself. And this is probably the biggest drawback using cladistics would have. A pure phylogeny without ranks (genera, families, orders, etc.) would have so many phyla nested into one another in matryoshka-doll-fashion that the resulting lists of vocabulary would cause lasting nightmares. As a very upset paleontologist remarks: „The cladists, seem, unfortunately, to have swallowed a rhyming dictionary […]; the resulting deposit has fertilized a plague of toadstools sprouting on our beautiful taxonomic lawn.“³ (Boucot, 1979)

Phylogenetic Taxonomy: A Useful Simplification
For this reason we have phylogenetic taxonomy. The same principle of monophyly applies here. And… Organisms are still sorted by their relatedness. The difference is that now, we are relieved of the burden to have to memorise every possible monophylum - whether it includes 2 species or half of all life forms. Instead we have useful ranks (genus, family, order, etc., as mentioned above) which allow us to skip over a lot of the intermediate monophyla. In other words, it is an overlay over phylogeny that blocks out all the „useless“ nodes, so that each species belongs to an „iconic“ group at genus rank, another one at family, etc. etc. all the way to kingdom.
However, more recently, taxonomists have decided that perhaps they needed finer ranks after all, and so they have introduced tribes, sections, complexes, and a lot of „sub-“s, „super-“s, „epi-“s, „parv-“s and whatnots…
Another big issue is that all ranks must be defined subjectively. It is not defined how close/similar two organisms have to be related to belong to the same genus, family, order… “It is the genus that gives the characters, not the characters that make the genus.“ (Linnaeus, 1737)
Essentially, it is up to the person writing the paper. (Side effects may include, but are not limited to heated debates about dandelions, and/or splitters vs. lumpers).
Additionally, genome fingerprinting has often placed species where we wouldn’t have expected them and has seemingly blurred the rule of thumb regarding the „gradually declining similarity“ (at least in a morphological sense)… So with all these drawbacks, how useful is phylogenetic taxonomy really?

Morphological Taxonomy: An Alternative?
If the main point of taxonomy is to be useful, and we already have a different system for accuracy, anyway, then it does not seem far fetched to base taxonomy on something else. The most intuitive „something else“ would be morphology. It is in our nature to lump things together by how they look. So, it might be far more „layperson-friendly“ to use a morphological taxonomy. A reptile can finally be a reptile without anyone having to worry about them pesky birds. All trees could be turned into a taxon, as it doesn’t matter that they are polyphyletic. And… honestly… whales and dolphins are basically fishes, are they not?
As you may be able to tell, I do not much like this idea. The resulting sterility would be a fungicide, killing off all of that wonderful toadstool-diversity on our beautiful phylogenetic lawn.
We should not use a worse model for simplicity’s sake. Too simple and a model becomes useless. A physicist may decide penguins are colourless cylinders, but us naturalists would then have a hard time identifying them.
In addition to that, a morphological taxonomy would leave even more room for subjectivity than the existing phylogenetic one.

Conclusion: iNat Taxonomy–My Opinion
The people who have seen my other posts and replies will know that I absolutely love giving my unqualified opinion on whatever topic currently talked about, so of course I will do the same here.
I have recently read multiple comments questioning the usefulness of a strictly monophyletic taxonomy on iNaturalist: Whether iconic taxa should be allowed to be para- or polyphyla (see this post by @charlie)–or entirely non-taxonomic entities (see this post by @jasonhernandez74), or whether strict monophyly is attainable or meaningful in general (see this post by @charlie). (I want to address a few of these points, but I’ll make an extra comment, as this post is far too long already)

So… what should iNat classification aim to be?
I will only say this: Phylogenetic Taxonomy seems to me to be the best compromise, despite its shortcomings. And while I know iNat does never suggest or invent taxonomy, I believe that whatever it uses, the principle of monophyly should remain untouchable in any modern classification. Learning about a species in the context of others teaches you more, IMO, than pure morphology does.

1: Tangley, L. 1998: How many species exist?, National Wildlife Federation

2: Dobzhansky, T. 1973: Nothing in biology makes sense except in the light of evolution, The American Biology Teacher

3: Boucot, A. J. 1979: Cladistics: Is it really different from classical taxonomy? in Phylogenetic Analysis and Paleontology, New York Chichester, West Sussex: Columbia University Press

P.S.: There may be mistakes
P.P.S.: It feels kinda pretentious for me, not a professional, to format a forum post like this (with “Introduction” and everything). But it ended up being so long that it just was overwhelming me without these “chapters”…

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@charlie I hope you don’t mind me continuing our discussion here, but as we were asked to keep the other thread on topic, I thought this would be a better place :)

I think „everything evolved the same amount“ can be easily misunderstood. The point behind it is „everything is up to date“ which means that every species is adapted to their current, modern environment which, as that is true for any given point in time, is roughly equal to „the lineage of every species today has evolved for the same amount of time“.
This also tells us that no modern taxon evolved from another modern taxon. Rather, two modern taxa share a common ancestor (features of which may be more conserved in one than the other)
„Everything evolved the same amount“ does NOT mean, that in every line the same amount of apomorphies have evolved. The rate of evolution in a species is (with limits) proportional to the rate of environmental change within or of the niche it inhabits (as you said, it happens in bursts). Stabler conditions will in general lead to fewer apomorphies & longer times between speciation events.

Regarding hybridisation, I do not think that with the above definition of the species concept (which is the standard definition that I learned, and is also a limiting factor for hyper-splitting species based on genome) it plays much of a role. Lions and tigers or different species of horse can mix under special man-made conditions, but this does not happen naturally. At least not to such an extent that it would affect the population in any significant way.

I do not understand how convergent evolution or mtDNA acting differently would make monophyly less useful of a concept. It would be great if you explained these arguments more.
Overall, however, cladograms only describe relatedness. Not function, form, ecological relationships, or anything else. Of course species affect one another and put evolutionary pressures on each other, but a cladogram does not attempt to show that.

So, I think that a dendritic cladogram is a very accurate representation of relatedness, especially when scaled for time. Speciation and apomorphies are the two central effects of evolution on species. And these can be accurately mapped with a dendritic cladogram and do not require a braided-river-like

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There are many taxa where observation after observation gets bumped back to genus with comments that they represent hybrids. If you push back, you are told that the hybrid swarm in that locality has been well-documented.

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If anyone cares to read even more discussion of this topic, there are these threads from the past to refer to. :P

Some relevant quotes from those threads:

A number of those hybrid swarms have been lumped and resolved now, but the one with Western Gull and Glaucous-winged Gull in the Pacific Northwest will probably never be because they aren’t even each others’ closest relatives (unless all Larus gulls get lumped into “seagull”, but that’s unlikely with Herring Gull just being split up even more this year…).

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Two comments. (Well, more than two, though that’s what I had planned.) First, monophyly is a good principle. It should be applied judiciously. I mean, sometimes people seem to be racing to the smallest diagnosable unit, wanting to name each of them as a species. Maybe that’s not always appropriate, from a practical viewpoint.

Second. Among plants, hybridization really does make many taxon boundaries less clear than we would like. That’s not too surprising. After all, being able to breed together is an ancestral condition. As two taxa diverge, it may not be the first trait to change. In fact, it may not change even when the taxa’s morphology becomes different enough that we can easily distinguish them.

Evolutionarily, plants are not in the same situation that large mammals or birds are. First plants tend to produce more offspring, spending less energy per offspring. Also, in very many cases, those seeds may have different pollen parents (fathers). Plants can afford to experiment, to produce some seeds that are hybrids. Also, after germination plants have to just stand there and deal with what the environment gives – they can’t go find a more suitable place. Therefore, a population with some genetic input from more distantly related plants may benefit.

All in all, I think the biological species concept (the one about interbreeding) is a good one and should be our “default.” However, we have to remember that we rarely assess interbreeding itself We look at patterns of morphological or genetic data and see if they show the kind of differences we would see if the populations are not interbreeding – if there are consistent differences. So our concepts may in fact be morphological even if we don’t think of them that way.

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Here are my main points on my taxonomy discussions on here that seem t get people so mad at me.

-We need to find a good balance of level of ‘species’ division that is appropriate for the needs of iNaturalist, field ecology, etc. The current push on iNat is to dramatically change the species and genus level identification of certain taxa, such as North American plants (just being the ones I am familiar with). I think it’s valuable to research things like the variability in common and frequently observed groups like Tiarella and Arisaema. I think it’s valuable to learn that the Tiarella at the north end of their range use stolons more to reproduce than the ones at the south end of their range. And of course, there are genetic differences between north and south due to distance and habitat differences. I think that’s all great. What i think is not great is making every bit of variability its own species. As discussed here there is no hard and fast discrete rule that determines what is or isn’t a species. Species is a human construct created by humans to understand life on earth. It’s part of a very valuable Linnean classification technique that includes more finely divided ranks like subsection and variety and more coarsely divided ranks like section and genus. We hear about ‘lumpers’ and ‘splitters’ but in reality there is plenty within the Linnean system to keep both happy. Lumpers can use species and section to group things, and splitters can use subspecies and variety. This used to be how things worked, but now there’s this push to get rid of subspecies entirely, and use species as the finest level of classification, even for new ‘microspecies’ being discerned by genetics and such which can rarely or never be identified in the field. This is iNaturalist, not iGeneticist, and we need ways to use taxonomy in the field as naturalists, which is what msot of us are. I recognize the push to make everything a species originates from outside iNat, and people are reluctant to push back on it. But some factions like ‘plants of the world online’ have become in my mind very extreme indeed. We are our own community and we choose what we want to do in-community. We have to make the best choices that work for everyone not just for taxonomists. Using the species rank is no more inherently scientific than using the subspecies rank. One compromise would be to use sections and species groups more (one division up) but people are very reluctant to that because taxonomists who are avid species-level splitters won’t create sections for their splits, either because they aren’t described in the literature (which is created by splitters for splitters with no consideration of how others use it) or because they are supposedly polyphylletic (i get why monophylly is a useful concept but is it necessary for every section, or even possible?)

We need a reasonable rate of change on iNat. I recognize people have a different definition of what is reasonable, but what i can tell you is both on an informal community science level and on an applied field ecology level, the rate of change on iNat is much too high and it’s getting adopted in the greater community. It’s just causing frustration. It also makes databases very hard to manage in a limited- resource field and is causing various other issues. I recognize change is needed over time, but there needs to be some balance as to how fast if we have any desire whatsoever for iNat to be usable to a broad audience. Right now, it’s becoming increasingly unusable. There needs to be some balance.

I know i’ve asked for a 10 year taxonomy freeze but i recognize that isn’t realistic in this community. So here’s what i think we should do instead. It’s not perfectly in line with the current taxonomic trend, but i don’t think it’s possible to be perfectly in line and have a functioning community here:

-Add new ‘splitter’ changes at the subspecies level instead of the species level. I recognize it’s a deviation from what POWO is doing, but POWO isn’t trying to run the largest community science enterprise in the world. Or create a level of classification between species and subspecies to ensure continuity.

-If that isn’t possible, create a section level entity for every split. It should be named after the original entity and contain only the new ‘species’ I recognize some of the taxonomists are bothered by this because they aren’t described in scientific papers (which were created to split up species not to run a database or community) bu tthis requires some sort of compromise and adaptation. Until this point the taxonomic splitter faction has gotten 100% of every bit of anything they wanted, despite the impacts on the community, and i’m sorry, but that just isn’t sustailable. My approach allows you to still track these variations without breaking the site for everyone else.

-Address issues created with rate of change instead of ignoring them. Listen when people say it is causing them problems. Put more energy into correct ID with the current system rather than completely upending the system on a very frequent basis.

-Separate taxonomic curation from moderation on the site so all taxonomic curators aren’t automatically moderators, which causes a lot of problems. Choose mods based on their kindness, ability to interpret rules, and fairness not based on their academic credentials.

Note that i am not saying it’s bad to describe that some Tiarella have stolons. It just needs to be described in a way that works for the community. We can’t follow the academic documentaiton perfectly beacsue it contradicts itself. We need to make hard choices, and that also includes splitters making compromises the way the rest of us who use the site have had to.

I’m sure i missed some points here but i need to go do work. I’ll come back and look at this later. Please don’t yell at me. I’m trying to save the site, not ruin it. And i truly, in my heart, see a community i love and care about moving in an unsustainable directon. My fear is iNat becoming unusable or even disappearing.

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All i mean is, so far as we know there has been only one life genesis or panspermia introduction to Earth, so every organism has ancestors going back the same amount of time to that point.

Many plants have very robust hybrid swarms with backcross gradient between them. It may not be true for mammals. I can’t speak much for mammals or whether mammal taxonomy is hypersplit or not.

It’s a useful concept it’s just not a silver bullet that gives us perfect taxonomic divisions. Things are very messy to say the least.

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I think this is by far the easiest solution and we have done a lot of that since the species complex option was added in 2019, but it’s still hindered by the fact that species groups aren’t an option yet. This creates issues where we’re using the “complex” option in places where it technically shouldn’t be which creates extra tension with people wanting to stick to the proper technical terms, and it also restricts flexibility since you can’t create a complex within another complex (I think we’re supposed to use “series” for that – again, technically incorrect and causes confusion).

I created or tried to help on flags on a lot of the large plant genera to get the ball rolling on introducing infrageneric taxonomy, but it’s a very slow process because it’s tedious to implement and before you can even do that you have to settle on what taxonomy system to use for the genus. Sometimes there isn’t a clear global taxonomy, other times there are competing ones. E.g. Ranunculus and Juncus still seem to be stalled.

Cladonia lichens are frustrating for identification because they generally can’t be ID’d to species, and morphologically the genus seems to have very clear divisions, except that those divisions apparently aren’t monophyletic. The consensus from taxon experts I tagged was to wait (probably for years) until new literature is published. I’m not going to go and implement my preferred taxonomy there if all the top observers and identifiers won’t like it, but it would help a lot of more casual observers…

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To be clear, I completely agree with you (and @jasonhernandez74) regarding the splitters vs. lumpers debate.
Hyper-splitting of species is probably one of the biggest disservices to taxonomy (and classification in general). And I think a reasonable definition of species (such as the one phylogeny offers –for animals at least) would prevent this.

I don’t think cladists are to blame for this trend (my professor, who is a cladist, has shared the opinion that apart from fulfilling the base requirements, species need to be morphologically distinct from all other species). Genetics should only be used to define (and refine) relatedness between organisms, not for creating classifications.

I personally think it is a “crime” that zoological nomenclature does not officially accept taxa below the rank of subspecies. And this is a good example where iNatters have done their own thing (we have formae for Harmonia axyridis, for example).
I think there should be four possible ranks (universally) below species: subspecies for morphological characteristics linked to geography, forma or variety for morphological characteristics not linked to geography, population, for geographic differences that don’t come with morphological characteristics, and cultivar for morphological characteristics caused by selective breeding.
This should give the splitters all creative freedom they could ever want, while leaving the rest of us with a useful taxonomy. (And it would enable us all to geek out about our favourite species.)

Ah. I see now, where I may have misunderstood your post. With “everyone evolved the same amount” not making sense you were talking about individuals “vertically” throughout time, not species at a given “horizontal” cross section of time? In that case I agree with this as well.

I must admit, that I have succumb to plant blindness here. Yes, there are many plant hybrids, which may make the “standard species definition” not really applicable to them. I am not aware of any described wild insect hybrids, which is the taxon I am most familiar with, probably.
I do think that definitions should be coordinated between the two so that the classifications of animals and plants are comparable.

I think the main difference between your view and mine is that I think that phylogeny offers a good solution for these problems which I don’t see being solved “neatly” by introducing paraphyletic or polyphyletic taxa for simplicity’s sake. IMO homologies (characteristics based on historic constraints) are more useful than convergences (characteristics based on environmental constraints) for creating a classification.

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Yeah, i probably did not explain that very well.

Yeah, that is fair. It just gets very hard though in cases like plant genii with large number of species some of which fit into very discrete groups (like Carex) where the discrete groups aren’t perfectly monophylletic or else we just don’t know if they are, but without making groups you are just stuck at genus level which given the diversity is probably the ecological equivalent of very broad mammal taxa like ‘primates’. We need a usable solution, and my main frustration i guess is the people changing the iNat taxonomy don’t seem to take this into account or weigh it very heavily. I feel like it’s treated like a game or challenge to keep the site as similar to PoWO or published papers as is possible, without considering that there are millions of data points by thousands of observers that are experiencing intense upheval every time there’s a change. What i want is balance, i guess i am not a good dbater and i sometimes state an extreme view on the other end hoping to meet somewhere in the middle. But if i ask for something in the middle i get ignored. My particular sub-neurotype doesn’t really recognize how to negotiate for compromise, i just see it all as a refusal to do so.

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What do you do if genetics clashes with practical identification?

I think this is a ubiquitous issue causing a lot of these conflicts, a particular example I can think of off the top of my head is with Elegant Tern and Sandwich Tern. The two species look quite different and are also separated by range; Elegant is only on the Pacific coasts of North and South America, while Sandwich is on the Atlantic coasts of North and South America and Europe and Africa.

Genetic work found that the eastern American subspecies of Sandwich Tern is actually more closely related to Elegant Tern than to the visually identical European subspecies of Sandwich Tern, making “Sandwich Tern” paraphyletic.

I don’t think anyone is going to accept lumping Elegant Tern and Sandwich Tern, since they’re clearly distinct morphologically and geographically. Elegant can interbreed with the more distantly related European subspecies, but rarely does so. But the other options are either accepting the paraphyly, or splitting Sandwich Tern apart. Currently the IOC taxonomy which Wikipedia follows splits them, while the Clements taxonomy which iNat and eBird follow keeps them together. I’m guessing they will split them in the future as part of efforts to align all the bird taxonomies together.

That’s a huge pain for birders though, since any Sandwich Terns that cross to the wrong side of the Atlantic would be a significant new species record but also very cryptic. I would prefer accepting the paraphyly, but that seems like a taxonomical heresy. What theoretical taxonomy trees might predict about differences between species just isn’t what happens when speciation happens in real life.

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this is the whole thing. it’s science, not religion, and how we classify things is a human construct. Who cares if it’s heresy. I guess this is why I piss everyone off but… keep it as a polyphylletic group because otherwise the species concept isn’t usable…

Like, us as a community, we can decide what to do, as long as the admins allow it. There’s no law of nature or of any said country where we are forced to go along with what some genetic survey says

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Hm. This is indeed an issue that would need to be answered, though with my lack of knowledge regarding these birds, I cannot really do so.

Were there any studies done on how much the Sandwich Tern actually crosses the Atlantic? Because if it doesn’t it at all or just very rarely, then I think there would be a big enough range-argument for identification, so a reclassification wouldn’t be that problematic.
Since there is a still significant amount of gene exchange between the two species, lumping them would be a solution. Species with significantly different subspecies aren’t unprecedented, even among birds (Setophaga coronata seems to have them (ssp. auduboni vs. ssp. coronata vs. ssp. goldmani)).

I am not an ornithologist, though, so like I said, I cannot actually answer this question.

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Yes, science is not a religion and shouldn’t blindly follow doctrines, but at the same time, we should try to keep it somewhat consistent. (There is a reason why most of the world uses the metric system instead whatever units they have used previously, for example.)
Using evolution and the principle of monophyly as guidelines offers a solution. And IMO, despite its shortcomings, it is the best potential solution anyone has come up with yet.

The taxonomic mess we have currently is in large parts caused by the lack of consistently applied principles and specialists of different taxa doing what they think is right without any coordination.
Generally, there won’t be a system that works equally well for everything, but IMO, having any such system at all would far outweigh these negatives.

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This always happens to me as well. One second I have a nice and brief comment drafted, and then I blink, and it has magically grown to novella-length, and it is three hours later… :P

I agree with your comments, though. They are very insightful. Plants benefiting from interbreeding and generally being able to afford these “hybrid-experiments” has never crossed my mind before, but from what I know about their development (and the differences compared with metazoan development), it makes a lot of sense. I’ll need to think about it some more. ^^

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Sandwich Terns of the “wrong” species occasionally cross the Atlantic both ways. It’s assumed to be rare but the birds are so hard to differentiate that it could be quite a bit more common than we realize.

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Given that this discussion is specific to iNaturalist, I think it might be helpful to separately consider how these issues affect different types of organisms and different levels of the overall taxonomic tree.

At the higher levels, the “iconic taxa” that iNat uses have some problems with polyphyly and paraphyly (e.g. birds are in fact a small part of the reptile clade). But, the iconic taxa are intended to provide a small number of easy high-level categories that are familiar to most people without specialist knowledge. It’s not really a problem if they are not monophyletic.

Also, quite a few of the higher level taxa in iNat do not accurately reflect recent-but-settled phylogenetic understanding (e.g. the iNat class Magnoliopsida is paraphyletic, lumping together Eudicots with Magnoliids and basal Angiosperms that split off before the Monocots). There could be a bunch of benefits to reworking this high-level taxonomy to better conform to monophyly, but there’s one huge drawback… The current iNat data structure appears to embed into each ID an implicit statement of its parent taxa all the way up the tree. Any taxon move that rearranges the tree requires a cascading update to every observation that has an identification that might now be a potential agreement or disagreement where it wasn’t previously. iNat staff vetoed this type of high-level taxon change several years ago when the impact was much smaller but already too high. Without a change to the underlying data structure, I can’t see high-level changes happening in any clade where there are more than a few observations.

Back down at the level of genus, species and below, we get to the area that most of us have to reckon with in regular use of iNat. For plants, we have, as mentioned by others, the challenge of dealing with polyploidy, hybridization, reticulate evolution, etc. But, in most cases, this is not something where iNat users and curators need to make the decision, because iNat defaults to POWO as its external taxonomic authority. (I’ll pause to acknowledge that @charlie and others view acceptance of POWO taxonomy as a major part of the problem.)

The way this is supposed to work is that researchers study organisms in the field, in collections and sometimes through sequencing. They bring together this knowledge to define taxa that are distinct under appropriate definitions of the species concept (I’ll side-step that minefield!) which (in my view) needs to include some type of morphological distinction, even if it requires some special analysis such as microscopy. They publish their new species, subspecies, synonymy, etc. This is then evaluated by the taxon authority (e.g. POWO), which decides whether to accept the taxonomic change.

In my view, this system is a pretty good foundation and has some huge benefits, such as getting iNat (mostly) out of the business of having to maintain its own taxonomy; ensuring that our taxonomy is relatively current; and better serving the purpose of identifying occurrences of threatened taxa and helping protect them.

I recognize that for @charlie and others, this approach moves too fast and is too willing to accept change without adequate consideration. I do understand that long-term ecological study becomes more complex when the names of taxa are constantly changing, and that correlating these consistently over time can be a laborious task. However, I feel that the current approach (at least for plants) is close to the “least worst” compromise that iNat could choose for a global platform serving everyone from high-school students to seasoned researchers and conservationists.

Certainly, I do see POWO accept taxonomic changes that in my view are ill-founded. But the correct response should be either to provide POWO with evidence supporting the alternative position, or to publish the research needed to invalidate the mistaken change(s).

For some organisms, we do have a problem that iNat’s “leaf taxa” are more “granular” than can be determined from typical photos. But I don’t think the response to this should be to prune valid, accepted taxa from the iNat taxonomy.

Instead I believe iNat could take several steps to make observers and the computer vision suggestion algorithm more aware of the “identifiability” of particular taxon groups. Right now, CV’s default is to assume that every species can be distinguished from all its sister species based on information present in a typical iNat user’s photo. That’s only sometimes true. It is almost completely accurate for a photo of a Tigridia flower from Mexico, and almost certainly wrong for my photos of micro-moths, looper caterpillars and blurry spiders.

There have been several proposals to adjust the interface to alert users when their observation appears to contain an organism that typically can’t be IDed to species from photos. And other proposals have suggested tweaking the CV algorithm to add similar awareness. I think these deserve attention from a working group of some sort and perhaps some testing of UI and CV changes on a small part of the tree of life.

I would like to see a future iNat where lots of arthropod observations get added at the level of genus or family because the photos typically only provide enough info for an ID at that level, and then a minority of these get moved down to species because knowledgable identifiers see the info they need to make those calls. That seems like a much better use of those identifiers’ time than to have them repeatedly have to add disagreeing higher-level IDs to hundreds of observations where CV has wrongly encouraged an observer to select a species-level ID.

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As far as I know there isn’t significant gene exchange between Elegant and Sandwich, since they’re isolated to separate coasts and neither breeds on the opposing coast. This is in contrast with Yellow-rumped Warbler where there is an extensive hybrid zone. I think the argument in favour of splitting those is that hybrids don’t seem to compete as well, which limits the hybrid zone so it doesn’t spread into a swarm encompassing the whole range. It looks like the IOC has it split into 3 species.

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In my opinion the best approach is generally following monophyly, but not dogmatically, recognizing that there are a few cases where it doesn’t work. Especially in the case of informal sections that may not be perfect but allow us to save the loss of massive amounts of data.

Well, iNat is a community i am invested in. it’s one that is accessible to me in a way academia isn’t due to neurodivergence, life situation, and other issues. It’s not reasonable to expect someone to change their career to taxonomist and spend tens of thousands of dollars going back to grad school to publish papers to fix things that don’t work for a community science site for naturalists. I get why you might wish we could do it that way, but it’s just not viable at all. POWO is pretty terrible in my opinion, and getting worse. Obviously some people don’t agree. But i hope you believe me that the site is getting very difficult to use for field ecology because of the constant change. Even if we ultimately decide to eventually link to POWO, waiting a few years to let it settle out seems like another valid middle ground. Unfortunately we instead have a few very active plant curators who are adding changes very quickly, often from unpublished non peer reviewed papers. In one case we had someone dramatically change a large genus removing several sections that were in wide use, based on an unpublished paper, and one of the paper’s authors appeared and told them it wasn’t ready for that. It tore a hole in a bunch of my data on here and was done mostly unilaterally (in theory i could have found the flag and commented, but it kind of becomes the taxonomic equivalent of the note the Vogons left for the Humans on Alpha Centauri when the humans didn’t have space travel). I don’t think most people realize how far some of the curators are taking this. That person wouldn’t reverse their actions either, a site admin had to do it. I think most of us can agree that at least this is a step too far… but there’s no real mechanism to balance this stuff at all, just me getting upset and getting called names for raising a fuss about it (someone called me ‘dim’ just today because i didn’t like a massive fern split). I know i’m not meant to link to individual observations or flags but… i wish people would just believe me that it’s much, much worse off than they realize if they aren’t directly involved.

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Charlie, could you give some concrete examples of where iNat’s current taxonomy causes problems for you?