Flag for Taxon: Copperheads, Cottonmouths, and Cantils (Genus Agkistrodon)
| Flagger | Content Author | Content | Reason | Flag Created | Resolved by | Resolution |
|---|---|---|---|---|---|---|
| bouteloua | Copperheads, Cottonmouths, and Cantils (Genus Agkistrodon) |
taxonomic updates |
Jul. 11, 2019 18:36:39 +0000 | Not Resolved |
see comments |
Comments
Sorry, not me. I am not willing to engage in reptile taxonomy management. Quite bluntly, I'm not interested in getting engaged in the constant fights that go on within it.
Sorry, @cmcheatle, but can you elaborate? I didn't know there were "fights" going on.
EDIT: @bouteloua I would be happy to help, but @loarie is the only taxon curator for reptiles right now.
Most of the needs listed above don't require being a taxon curator.
(And let's keep this thread focused on the taxonomy)
@bobby23 - there is a long-standing and still ongoing pattern of pretty dire behaviour among some of the more passionate members of the reptile community regarding iNat taxonomy, practices and even directed at individuals.
I don't think the issue deserves additional oxygen or focus to continue to drive it, but if you really need examples, I can send them to you privately.
I personally am simply not interested in being dragged into the stuff, so will focus my volunteered curating time elsewhere.
Ranges and atlases have been updated for the cottonmouths too https://www.inaturalist.org/taxon_changes/59156
A. contortrix changes committed aswell:
https://www.inaturalist.org/taxon_changes?change_group=Agkistrodon%20contortrix%20env
https://www.inaturalist.org/taxon_changes?change_group=Agkistrodon+contortrix+swing-split
https://www.inaturalist.org/taxon_changes?change_group=Agkistrodon%20contortrix%20env%202
https://www.inaturalist.org/taxon_changes?change_group=Agkistrodon+laticinctus+env
Oh what fun... the Burbrink & Guiher paper provided every possible reason why neither conanti nor laticinctus should be separate species, in the shape of massive zones of introgression.
Implementing this change now means that cottonmouths from a broad swath of the southeast, from southern Mississippi to southern Georgia, will now have to be called Agkistrodon sp., and ditto for copperheads all the way from E Kansas down to E Texas. For anyone who thought the ratsnakes were a mess, welcome to this clusterfudge.
An earnest suggestion: dispense with the individual species designatons for both, and just have a single category called "Cottonmouth (Agkistrodon piscivorus / conanti complex)" and "Copperhead (Agkistrodon contortrix / laticinctus complex)". At the end of the day, the vast majority of the user community simply wants to know whether it's a copperhead, or a cottonmouth.
And most of this also applies to the Vipera berus / nikolskii split.
NB: getting rid of the various subspecies (leucostoma, phaeogaster, mokasen etc.) was a valid move supported by good evidence from Burbrink & Guiher.
@wolfgang_wuster what do you advise? (a) keep as is, (b) lump back together, (c) add 'complex' nodes (d) other?
Thanks for responding!
I would lump back together.
It corresponds to the evidence actually presented in the Burbrink & Guiher paper, which documents large intergrade zones.
I think there will be pushback against that paper before long - there are certainly papers in the works about some of the other N. American splits that show them to be ill-advised, and many of my colleagues take a dim view of this one
In terms of the iNaturalist user community, I suspect that the vast majority would prefer to just know whether they had a copperhead or a cottonmouth...
I should add for the record that the Burbrink & Guiher paper had lots of good information and data in it, it was innovative and rigorous in many ways, and I agree with the sinking of the old ssp., especially of copperheads. It's just that I (and many others) don't feel that the data presented really support species status. When you have a hybrid zone between A. piscivorus and A. conanti that's as large as the entire distribution of A. conanti, then I find it hard to argue that these are independent evolutionary units... but I don't want to convey the impression that the paper was bad from beginning to end - not at all.
and your suggesting that both copperhead and cottonmouth should be monotypic (ie no ssp)?
curious what others think
No, conanti and laticinctus should be listed as subspecies - they are clearly distinct entities, albeit with wide intergrade zones. But for those, we can then simply leave out ssp. designations and still call them A. contortrix or A. piscivorus while staying within the system.
My preference would be to follow our external taxonomic authority or at least contact them before making additional changes. I would also prefer that we use "complex" designations conservatively (in other words, as scarcely as possible), but this discussion should probably include more users/curators who are familiar with snake taxonomy (as oppose to me, who is not).
This is a tough one: iNaturalist clearly should not be a taxonomic innovator, but at the same time, the current Reptile Database classification is difficult to reconcile with the way that iNaturalist works, as well as being contentious within herpetology itself.
As a basis for discussion, here is my perception of the pros and cons of different options:
Treat copperheads and cottonmouths as single species, with laticinctus and conanti as subspecies, respectively.
Pros: probably best reflects genetic evidence, esp. for cottonmouths; gives single species-level ID that many users will most want ("It's a cottonmouth!"); no complex explanation needed.
Cons: goes against Reptile Database and the latest published research paper (Burbrink & Guiher); could be seen as political or a snub against the authors of the latter.
Call both copperheads and cottonmouth complexes - so Copperhead (Agkistrodon contortrix / laticinctus complex) and Cottonmouth (Agkistrodon piscivorus / conanti complex). This could be applied either across the entire range of both, or restricted to the hybrid zone while recognising the laticinctus and conanti as full species.
Pros: Less political than keeping them as single species; reflects complexity of situation
Cons: complicated. If used only for specimens from hybrid zones, it loses the overall information many will want ("It's a cottonmouth!"), and it will complicate data searches. If used for the entirety of the range of each complex, it will lose the substructuring into the lineages piscivorus and conanti or contortrix & laticinctus, respectively.
Accept conanti and laticinctus as species, call specimens from introgression zones hybrids (piscivorus x conanti, contortrix x laticinctus)
Pros: in keeping with Reptile Database and latest revision paper
Cons: many would not regard it as consistent with the evidence; loses sight of wood for the trees ("It's a cottonmouth"); loses clear assignation of many observations across large areas to an unambiguous species; will complicate data searches.
Accept conanti and laticinctus as species, classify specimens from introgression zones simply as Agkistrodon sp., as implemented by default in the initial taxon split
Pros: none
Cons: untenable - we do know whether we are looking at a copperhead, cottonmouth or cantil!
I hope that helps stimulate thought and discussion. More views would definitely be useful.
thanks for that framework - I think in terms of disruption they are already ordered properly with 1 being the most disruptive and 4 being the least disruptive.
I take your point that if people can't tell 2 nodes apart, and they form a clade its useful to have a way of grouping them for practical iNat purposes if nothing else. I also agree that the researcher community shouldn't split monophyletic clades that intergrade and lack clear boundaries.
I think I'm personally most in favor of 2 because it will provide nodes for people to access the combined 'cottonmouth' and 'copperhead' concepts (and an anchor for potential future more disruptive lumps) but doesn't require deviating from RD or another disruptive taxon change (We can also make it so that IDs that were reassigned to Akistrodon sp. in the recent splits are reassigned to these nodes to try to mitigate damage done)
I would argue that option 1 is the least disruptive - we return to the status quo ante and pretend the last 72 hrs didn't happen ;)
In the meantime, what seems to be happening out there is the gradual implementation of option 3 by the user community, with specimens from the intergrade zones being assigned to hybrid status. Democracy at work, I suppose.
@wolfgang_wuster this can't really be reverted so option 1 would require another big taxon change touching every identification, making them non-current and making new ones etc. Are you opposed to option 2?
Given where we are and what you wrote, I guess either option 2 or option 3 are the best we can do (I am not clear as to whether these have different implications for searchability).
Ok I'll replace with complexes (option 2) I'll also replace this hybrid with a complex see https://www.inaturalist.org/flags/443772
Yes, definitely implement the same treatment for copperheads and cottonmouths.
I agree with the species complex option being the best available solution in those areas of overlap. It doesn't make any implication as to the possibility of individuals being hybrids.
The same policy should probably be applied to Lampropeltis holbrooki and splendida as well.
Looks like I was late to the party, but as a curator of a major natural history collection of reptiles and amphibians and also a major contributor of tissues the the burbrink and guiher paper we will not be making taxonomic changes within our collection based on this paper. I agree with Wolfgang's comments that we should be able to call "hybrids" A. laticinctus/contortrix or A. conanti/piscivorus.
I closed this related flag to consolidate the conversation here https://www.inaturalist.org/flags/443772
revisiting this - are people satisfied with the current status of things (meaning we can close this) or is there consensus about what change we need to make?
The obvious change would be to go back to the biological reality very aptly demonstrated by Burbrink & Guiher's (2015) excellent paper, that there is one species of cottonmouth and one species of copperhead, each with two partially independent sublineages that could usefully be called subspecies... See Hillis (2019, 2020). I understand there is work in progress to address this issue.
Hillis, D.M. 2019. Species delimitation in herpetology. J. Herpetol. 53:3–12.
Hillis, D.M. 2020. The detection and naming of geographic variation within species. Herpetol. Rev. 51:52–56.
that would involve making a deviation from RD and then lumping the cottonmouths and copperheads back together.
Agkistrodon piscivorus, Agkistrodon conanti -> Agkistrodon piscivorus
Agkistrodon contortrix, Agkistrodon laticinctus -> Agkistrodon contortrix
with no ssp?
I'm not thrilled about changing everything again, but if people feel like its stable and aren't happy with it being how it is we can do it
I think these groups (copperheads, cottonmouths, kingsnakes, etc) are all in a state of flux. I suspect many will go back to some semblance of the older arrangements in the near future, but maybe the status quo is better until there is something published we can lean on?
Living in a copperhead "hybrid zone" and making observations of them regularly is always frustrating for me. The last thing I want to do is to defend my use of either of those species especially when I don't think and the data don't show that they are separate entities. Through time as project curators we have more or less decided on arbitrary lines to split the "species" and have done the same thing for things like kingsnakes and milksnakes (at least within Texas). I guess what I am saying is that although I don't like the split, if we are going to follow the Reptile Database then we probably should stick to that and make unwritten work arounds within our regions until the taxonomy is more settled.
I guess reverting at this point, in the absence of a clear, citable refutation is not great choice. I would however argue that it would have been better if the split had never been implemented.
As was also discussed over the various lineages of western rattlesnake (Crotalus oreganus), situations like this, where authors have split species despite the demonstrated existence of extensive introgression zones, might be cause for deliberate departures from the Reptile DB - there are operational reasons for that on iNat, where broad introgression zones cause things to end up in limbo. Even now, there are over 600 records of Agkistrodon that "Need ID", when in reality the overwhelming majority can be 100% identified as obvious "copperheads" or "cottonmouths" without even going beyond the thumbnails. There is a lesson in that...
option 1:
leave as is
option 2:
create new 'complex' nodes between genus and these species
option 3:
deviate from RD (treat as sensu lato) and lump accordingly
I like the idea of the complex node option (Copperhead Complex, Cottonmouth Complex). I know it is a bit of a pain to put together, but at least we could get those taxa identified to "species group" rather than just genus.
And then when this is resolved it will be much simpler to put them all back together. Either we will know the geographical boundaries between the species and can resolve it that way, or more likely, we can lump them back into a single species when that happens.
Option 3 (first preference) or 2 (second preference)
Agkistrodon contortrix and A. laticinctus
A. contortrix laticinctus --transferred to--> A. laticinctus laticinctus (taxon change)
A. contortrix pictigaster --transferred to--> A. laticinctus pictigaster (taxon change)
A. contortrix sensu lato --split into--> A. contortrix sensu stricto, A. laticinctus, and hybrid (taxon change)
Needs prior to committing A. contortrix taxon changes:
1. Text description of reason for each change2. Atlas and range for A. contortrix sensu stricto, A. laticinctus, and hybridReview of whether the above list of changes, ranges, and atlases are accurate/complete
---------------AND
Agkistrodon conanti and A. piscivorus
A. piscivorus conanti --elevated to--> A. conanti (taxon change)
A. piscivorus sensu lato --split into-->A. piscivorus sensu stricto and A. conanti (taxon change)
A. piscivorus piscivorus and A. piscivorus leucostoma --lumped into--> A. piscivorus sensu stricto (taxon change)
Needs prior to committing A. conanti/piscivorus taxon changes:
1. Text description of reason for each change2. Atlas (and ideally range too) for A. laticinctus3. Atlas (and ideally range too) for A. piscivorus sensu stricto4. Atlas (and ideally range too) for A. conantiReview of whether the above list of changes, ranges, and atlases are accurate/complete
Can someone please help with this?
(comment edited)