The Peril of Clairvoyance in the Freshwater Gastropoda

I feel compelled to call the attention of our group to the video clip below, which aired on Comedy Central's "Colbert Report" 3Jan12, the night of the Iowa caucuses [1]. You may need to hit the "unmute" button at the lower right corner of the screen:

The Colbert Report
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So I gather that from an audience perspective, that was pretty funny. But was anybody thinking about the snail?

I am 95% sure that "Megyn Shelly," the brunt of the hilarity in Mr. Colbert's cruel prank, was a young adult Pomacea bridgesii [2] - the South American ampullariid that has risen to such popularity with aquarium hobbyists in recent years. I believe that's the variant with the albino body but pigmented shell [3].

So of course "Megyn" could not move when placed under the heat of Mr. Colbert's swirling spotlights - freshwater gastropods are notoriously immobile when suddenly transported into the terrestrial environment. In fact, she was holding her breath, fearing for her life. As Colbert and his heartless audience mocked and scorned! How could such a travesty be perpetrated?

I would speculate that Mr. Colbert suffers from a dearth of malacological expertise in his staff of comedy writers. So my guess would be, judging from the podia, that the part of Megyn Shelly was originally written for a land snail. And that only after plans were made, and cucumbers assembled, was some young intern tasked to call the local pet shops and audition a star for the show. On a short time line.

But I am not sure, even in New York City, that one can find a living land snail for pickup on short notice. Those things are pretty much all potential agricultural pests, every one of them, and the interest in the pet trade must be very close to negligible. One might order Helix aspersa from a biological supply company, but such an approach would have been no help to our young intern, who needed a star for the show that very evening.

So the talent agent at the pet shop on the other end of the telephone might well have responded to her renewed entreaties, "We've got some decent-sized aquarium snails we could sell you this afternoon." And by such a scenario, victimized by malacological fashion, USDA regulation, and cruel fate, I should speculate that our luckless ampullariid found herself dewatered on national television, to the general hilarity.

I know you read this blog, Colbert, and I have a prophecy for you. At the present writing (February 3) only four candidates remain in the running for the Republican presidential nomination. You endorsed Herman Cain right here on the CofC campus January 20, but Herman Cain endorsed Newt Gingrich eight days later. I predict this wave will carry Newt Gingrich to a victory in November.

A Gingrich presidency will cast a shadow over your rich, liberal, New York media establishment no different from the darkest hour of the McCarthy Era, Colbert! Megyn may have seen her low-water mark on your television show that fateful night of January 3. But you have seen your high.


Notes

[1] The clip can be viewed in a slightly larger format back at the Comedy Central mother ship here [Comedy Central].

[2] Is the common aquarium pet now being referred to P. diffusa? I saw an oral presentation from Ken Hayes at the AMS in July that suggested a huge amount of revision on the horizon for the Ampullariidae, including yet another name change for the invasive populations we're now calling P. insularum. But I haven't seen anything published since 2007. Have I missed a paper? Ken or Rob, would you care to enlighten us?

[3] There's a very nice website dedicated to apple snails in the aquarium run by a dedicated hobbyist named Stijn Ghesquiere here [applesnail.net]. The site features a cute (and credible) "hypothesis" regarding the genetic basis of the various color forms seen in P. bridgesii. But I do wish somebody would undertake a good, old-fashioned, Mendelian breeding study! And publish something formal.

Toward the Scientific Ranking of Conservation Status - Part II

Note: This essay was subsequently published as FWGNA Circular No. 1 (19Mar12).

Since the birth of their discipline, community ecologists have been interested in a phenomenon generally called “the distribution of commonness and rarity.” If one surveys bird abundance on a set of Pacific Islands, for example, certain patterns (e.g., all bird species equally common) do not seem to occur. Rather, what one typically finds is that a few species seem to be very common, and many species seem to be very rare. Such observations led to the development of several prominent theoretical models to explain the distribution of commonness and rarity, each based on slightly different assumptions about the processes that might be ordering biological communities. The best review of this literature I know is the 1975 work of Robert May [1].

The model that ultimately rose to prominence was the lognormal. In my book I gathered data from ten communities of freshwater mollusks (three of gastropods, five of unionid mussels, and two of pisidiid bivalves) and confirmed lognormal distributions for five of them, including the gastropod communities of Oneida Lake, NY, and Lake Esrom, Denmark [2].  A lognormal distribution of commonness and rarity is hypothesized to reflect “minimal structure” in biological communities [3]. If (for example) species #1 takes a random portion of the total resource, then species #2 takes a random portion of the remainder, then species #3 takes a random portion of the remainder, and so forth, a lognormal distribution of abundance will result.

Although (as far as I am aware) the lognormal model has not been extended beyond community ecology, it seems plausible to me that such “minimal structure” might generalize to evolutionary time, and find application to the regional (or even continental) distributions of related organisms no longer competing, or indeed even interacting, in any way.

For example, across the southern Atlantic drainages the FWGNA project has recorded 593 populations of Helisoma anceps and 192 populations of Helisoma trivolvis. But because H. trivolvis is adapted to lentic environments and H. anceps to lotic, they rarely occur together. The same relationship exists between Gyraulus parvus and Menetus dilatatus, and between Amnicola limosa and Somatogyrus virginicus, and in several other pairs and groups. This sort of “minimal structure,” integrated over the evolutionary history of the freshwater Gastropoda, might plausibly lead to a lognormal distribution of commonness and rarity at a scale much larger than the single biological community.

From the Atlantic drainages of the four southeastern states, the FWGNA Project has recorded the 57 species of freshwater gastropods ranked down the left margin of Table 1 [4] by the total number of lines in our database [5]. The most common species across the region was (somewhat surprisingly) Campeloma decisum with 1,188 records, followed by Physa acuta with 1,082 records, and so forth, down to four species (Gyraulus deflectus, Valvata tricarinata, Fontigens bottimeri and Marstonia gaddisorum) with one record each.

Because data of this sort are typically found to contain many singleton values, the convention in community ecology has been to use base-2 log transformation. Thus log2 abundances for all 57 species are given in Table 1 and plotted in Figure 1, to the left above [Note 6, click for larger].

A lognormal hypothesis does indeed fit the distribution of commonness and rarity of the 57 freshwater gastropod species of southern Atlantic drainages (Shapiro-Wilk W=0.962, p<0.065). The mean of the distribution shown in Figure 1 is 4.83 (= 28.4 records), with a standard deviation of 2.96 (= 7.8 records).

In recent years a widespread practice has developed wherein species are prioritized for conservation purposes into a system of five “status ranks” [See the previous post in this series – Note 7 below]. Convention would dictate that special consideration should be given to the rarest 5% of the species, 1.64 standard deviations (or more) below the log mean abundance. Shall we assign such especially-rare species to “Rank-5”? Then Rank-4 species might be those with log abundance less than 1.64 standard deviations below the mean but greater than 1 standard deviation, and Rank-3 species might be those between 1 standard deviation below the mean and the mean itself. Let us assign Rank-2 to species with log abundances greater than the mean but less than 1 standard deviation above, and Rank-1 to all species with log abundances greater than 1 standard deviation above the mean.

Figure 1 shows that the 57 freshwater gastropod species of southern Atlantic drainages include just the 4 singletons at Rank-5, an additional 7 species at Rank-4, 17 at Rank-3, 17 at Rank-2, and 12 species at Rank-1. The conservation ranks of all 57 species are given in the far right column of Table 1.

The implications of adopting such a system to guide conservation decisions more generally, in other groups of organisms elsewhere, would bear considerable discussion. Perhaps we will devote a third essay to this question in some future month. For now I will close with this.

It will be obvious to any of my readership with a general appreciation of the North American freshwater gastropod fauna that two of the four species here designated as “Rank-5” are narrowly endemic and genuinely rare (the two hydrobiids) and that two of the four species (Gyraulus deflectus and Valvata tricarinata) would have become much more common had our survey been extended further north. Clearly, the ranks we have assigned in the present exercise are dependent on the region surveyed. Thus we propose to call this set of 57 “FWGSA” ranks – Freshwater Gastropods of the Southern Atlantic drainages [8].
And more generally, the stability of any ranking system based on abundance data will be a function of the area surveyed – the smaller the area, the more unstable the classification. So although the regulatory apparatus for conservation purposes (and grant funding!) is largely administered by the states, we have resisted the temptation of calculating state-level abundance ranks here. Rather, we anticipate expanding our area of coverage, ultimately to include the entire continent, at which point we will publish FWGNA ranks, perhaps characterized by some stability.

But in any case, the system described above is rigorous, objective, and theoretically-based. In short, it is a scientific method to assign conservation status ranks, heaven help us.


Notes

[1] Although I dabbled in community ecology early in my career, I admit I have not kept up with the literature. There is probably something more current than this:
May, R. M. (1975) Patterns of species abundance and diversity. Pp. 81 – 120 in Ecology and Evolution of Communities (M. Cody and J. Diamond, eds). Cambridge, MA: Belknap Press.

[2] Pp 421 – 428 in Dillon, R. T., Jr. (2000) The Ecology of Freshwater Molluscs. Cambridge University Press. [website]

[3] Sugihara, G. (1980) Minimal community structure: An explanation of species abundance patterns. Am. Nat. 116: 770-787.

[4] Table 1. The 57 species of freshwater gastropods inhabiting the southern Atlantic drainages of the United States, ranked by their abundances in the FWGNA database 1/2012. [pdf]

[5] Each line in the FWGNA database records the collection of a single species at a discrete site. We have screened any date-duplicates from the databases we have obtained from secondary sources, including museums and state natural resource agencies, as well as any nearly-neighboring collections, such as those taken upstream and downstream of single bridges.

[6] Figure 1. Log2 abundances of the 57 freshwater gastropod species inhabiting the southern Atlantic drainages of the United States, divided into five categories (“FWGSA Ranks”) as described in text. [jpeg]

[7] Toward the Scientific Ranking of Conservation Status – Part I. [12Dec11]

[8] A paper including the text of both my December and January essays, together with Table 1 and Figure 1, was  initially made available as a pdf separate on 9Jan12.  That paper was updated on 19Mar12 as [FWGNA Circular No. 1].

Toward the Scientific Ranking of Conservation Status - Part I

Editor’s Note. This essay was originally published in FWGNA Circular No. 1 (19Mar12).  It was subsequently published as: Dillon, R.T., Jr. (2019d) Toward the scientific ranking of conservation status.  pp 223 - 227 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

Last month I got an email from a colleague in the South Carolina Department of Natural Resources, asking for my help updating the state wildlife conservation plan. I told him I'd be willing to pitch in with the 2011-12 effort, just as I helped in 2004-05 [1]. But I continue to harbor deep misgivings about the entire process.

In Part I of the essay that follows, we debride a nasty sore on the left butt cheek of American environmental science - the unscientific (possibly pseudoscientific) method by which we prioritize our biota for conservation purposes. And in Part II of this series, to follow next month, we will begin the process of suturing that wound back up.

Like all other states with which I am familiar, South Carolina’s wildlife plan relies upon a subjective system of conservation status ranks, as follows:

S1 - Critically imperiled state-wide because of extreme rarity or because of some factor(s) making it especially vulnerable to extirpation.
S2 - Imperiled state-wide because of rarity or factor(s) making it vulnerable.
S3 - Rare or uncommon in state.
S4 - Apparently secure in state.
S5 - Demonstrably secure in state.

The spreadsheet my DNR colleague sent me for my input [2] had a column for species number (N=32 freshwater snails in South Carolina), scientific name, common name, legal status, conservation status rank (as above), and an (astonishing!) 19 additional data columns, more about which later. My colleague asked me to complete this massive 32x24 matrix by January 15, indicating as he did that the results would (ultimately) be forwarded onward to the nonprofit organization, NatureServe.

The origin and evolution of the conservation ranking system in general currency around the United States is shrouded in mystery. According to documents available from the NatureServe website [3], the notion of a state "natural heritage inventory" arose from collaboration between the nonprofit Nature Conservancy and my very own South Carolina back in 1974, with the first (A-B-C) system of conservation status ranking appearing in 1978. The current five-tier system was developed in 1982. In 1994 a group of state natural heritage program directors formed a related but independent nonprofit organization called the "Association for Biodiversity Information" to catalog the rising flood of inventory and status ranking data, which (in some complex fashion) led The Nature Conservancy to spin off "NatureServe" in 2001.

The 1982 system featured ranking at three scales: Global (G-ranks), National (N-ranks), and Sub-national (S-ranks), based on eight "factors" scored by anonymous participants. The number of factors taken into consideration has increased over the years, as has the number of participants, as has the elaboration of the technique by which the body of anonymous opinion is reputedly converted into a system of conservation status ranks.

For example, the 19 columns on the right side of the matrix my SCDNR colleague sent me last month included

• Knowledge of the species population status - "High" if we know the status throughout the species range, "Medium" if we know the status in select areas, "Low" if we know little to none.


• State Threats - "A" if very threatened, "B" if moderately threatened, "C" if not very threatened, "U" if unthreatened.


• Feasibility Measure - How likely is it that conservation activities can make a difference for this species (High, medium, low).

Any reader curious regarding the actual analytical technique by which standard international ignorance units (SIIUs), state threat quotients (STQs), feasibility metrics (FMs), and 16 similarly baffling variables counted and scored for each species are converted into the critical-imperilment-demonstrable-security scale on the global conservation status gauge is invited to peruse the voluminous documentation available from the NatureServe website [4].
This is obviously not science. Conservation status ranks, as they have been propagated throughout the entire natural resources community for 30 years, are not testable, verifiable or falsifiable. The entire system is, at its very foundation, anonymous, unaccountable, subjective opinion.

Are conservation status ranks merely unscientific, or are they pseudoscientific? Pseudoscience is “a claim, belief, or practice which is presented as scientific, but which does not adhere to a valid scientific method [5].” Thus the difference between harmless non-science and execrable pseudoscience is in its presentation.

To the extent that the conservation status ranks arising from this system are presented honestly, as an opinion poll of mysterious parameter, I think they can be excused as (at worst) innocent claptrap. Is there any better solution to the genuine challenge of prioritizing species for conservation? Are we not doing the best that we can in a difficult situation? This is America - take a vote. Fine.

But if there is any effort or intent to present conservation status ranks as scientific, then we as a community will be guilty of promulgating pseudoscience. The elaborate machinations of NatureServe, which have developed over the years into a byzantine system of coding and computation, look suspiciously like dressing a pig in a ball gown, especially when standing behind a velvet rope, looking towards the sty.

And when we scientists make use of conservation status ranks, we give the appearance of endorsing the process that brought them, turning nonscience into pseudoscience by the very act. Surely we wouldn't reproduce conservation status ranks in our peer-reviewed journals, would we? Surely, surely we scientists wouldn't gin up some "crisis" on the basis of such a system, in a self-serving ploy to attract funding for our own research programs, would we? To do so would be to commit pseudoscience of a high and aggravated nature.

I absolutely understand why natural resource agencies personnel rely on conservation status ranks for their state wildlife action plans. The state of South Carolina cannot launch inventories of every bug, slug, and butterfly within its vastly triangular borders every five years to meet the data requirements of each fresh wave of federal regulation [6].
But as scientists, we must be very clear that the current system of conservation status ranking, as implemented by NatureServe, cannot be endorsed.

The FWGNA project has now developed a large database with objective estimates of the abundance of all 57 species of freshwater snails inhabiting the Atlantic drainages of the southeast. In the next installment of this series, I will propose a new method to rank these 57 species into five categories of abundance for conservation purposes. But while this approach is designed to mimic the existing system of status ranking currently in favor throughout American conservation biology, it has a theoretical basis and will be rigorously objective.

Stay tuned...
Rob

Notes
[1] I reviewed the 2005 South Carolina wildlife plan together with the plans of nine other southeastern states in my essay, "Freshwater Gastropods in State Conservation Strategies - The South." [26May06]

[2] The header indicated that this particular data matrix has been developed in collaboration with North Carolina and Georgia. I was peripherally involved in the Virginia process back in 2004, and it wasn't quite as elaborate.

[3] See the brief history of NatureServe on its "Tenth Anniversary" page.
[4] NatureServe Conservation Status Assessments:
Methodology for Assigning Ranks

[5] This is from Wikipedia, which is the first hit one gets, if one googles it.

[6] I’m surrendering to reality here. In fact, the FWGNA has surveyed most of five states for less than $20k in total grant support. I suppose the entire country could be done for $200k. Land snails and bivalves for similar figures? Each order of insects? We’re probably talking several million dollars to inventory the biota of the entire country. I suppose that’s too much to ask.

The Freshwater Gastropods of Tennessee

The FWGNA project is pleased to announce the launch of our new web-based resource, "The Freshwater Gastropods of Tennessee," by R. T. Dillon and Martin Kohl. This brings to five the number of states currently covered by the project.

Our study area extends only over the eastern third of the state at the present time, to cover the Tennessee River and its tributaries upstream from the Alabama line just south of Chattanooga. But the area also includes 8 counties in southwest Virginia, 15 counties in western North Carolina, and 7 counties in north Georgia, for a total catchment of approximately 57,000 square kilometers.

A total of 38 freshwater gastropod species are documented from 766 sample sites, with distribution maps, taxonomic notes, a dichotomous key, a photo gallery, and conservation recommendations. Here’s the direct link:
The Freshwater Gastropods of Tennessee
.
Pleurocerid snails often dominate the macrobenthos in this part of the world, especially in the smaller rivers and creeks that have escaped impoundment by the TVA. The spectacular morphological diversity demonstrated by the East Tennessee pleurocerid fauna led 19th-century authors to recognize at least 140 specific nomina, which Calvin Goodrich pared down to approximately 31 in 1940. Our review suggests that a better estimate of the biological species of pleurocerid snails inhabiting East Tennessee would be (a still impressive) 15.

Against this background, perhaps the most interesting finding of the present survey is the discovery of one valid biological species of pleurocerid snail that seems to have been entirely missed, in 200 years of shooting, 140 rounds fired. A formal description of this new "skinny simplex" species is currently in manuscript.
.
Our appreciation is due (once again) to the Virginia Department of Game & Inland Fisheries for support of this work, as well as to the Office of Inventory and Monitoring at the Great Smoky Mountains National Park.

Megapetitions III: The 17-month, 90-day finding

On 27Sept11, the US Fish and Wildlife Service published "Partial 90-Day finding on a petition to list 404 species in the southeastern United States as endangered or threatened with critical habitat (1)." Cradled deep in the bottom of this stupendous ark-full of creatures were 43 species of freshwater gastropods: 15 Mobile Basin pleurocerids, 9 Tennessee Basin pleurocerids, 10 Florida hydrobiids, and 9 miscellaneous. A pdf with the specifics is downloadable from note (2) below. Any of us with "scientific and commercial information" relevant to the listing of these 43 species is requested to transmit such data to the FWS by November 28.

What a dramatic turn of events! In the first episode of our long-running series (3), we were introduced to the Center for Biological Diversity, a posse of lawmen riding out of the American West "with a vision and a solar-powered fax machine," filing megapetitions to list 32 miscellaneous gastropods from the Pacific Northwest in 2008 and 42 Great Basin springsnails in 2009. In our second episode (4), the CBD gunslingers upped the ante with their (2010) "Petition To List 404 Aquatic, Riparian And Wetland Species From The Southeastern United States" even as the lily-livered WildEarth Guardians, an outfit with similar goals if not similar fortitude, was settling with the FWS black hats.

Now we learn that the standoff between the CBD and the FWS was resolved on July 12, and that a federal judge has approved a settlement of the case on September 9 (5). And that the CBD has declared an "historic victory (6)."

And in today's episode, sure enough, the FWS seems to have run its finger lightly through the CBD Southeastern list, trimmed 30 species (most already under consideration - Note 7) and forwarded the remaining 374 to us for comment in a lightning-fast 16 days. Presumably we will see similar "notices of review" regarding the 32 Pacific Northwest and 42 Great Basin species published in the Federal Register shortly. Those of you with expertise in western faunas are hereby alerted to be on the lookout.

Throughout the saga thus far, the matters at contest have been entirely legal. The endangered species act specifies a strict timetable: 90 days from the receipt of a petition to the publication of a "Notice of Review," 12 months of "status review" to decide whether a species warrants listing, another 12 months (if warranted) to publish a proposed rule, and another 12 months of hearings and fussings to publish the final rule. The CBD has not been suing the FWS over any scientific question, but simply to have a legal timetable enforced.

So at this point, it has taken 17 months for our 374 southeastern species to advance through the first 90 days of the process. (And of course, the Pacific Northwest and Great Basin species have been in the pipeline for several years without reaching their 90-day marks as yet.) How long might the next step of this process take? Quoting directly from the FWS Headquarters press release of 26Sept11, "At this time, however, the 12-month findings are not scheduled to be completed within the next six years due to the priorities detailed in this court-approved work plan (8)."

There it is. This reminds me of one of my favorite lines from one of my favorite movies, Mary Poppins. Early in the movie, Mr. Banks comes home and demands to know where his children are. To which Katie Nanna replies, "The children, to be precise, are not here."

So our 12-month status review, to be precise, will not be complete within six years. A tip of the Stetson to Sheriff Noah Greenwald, and all his posse at the CBD, for an "historic victory" indeed.

But let's not get ahead of ourselves. Meanwhile, back at the ranch, the FWS has given us ordinary cowpokes precisely 60 days to submit the "best scientific and commercial data" we've got regarding the 43 southeastern freshwater gastropod species listed in Note (2). That 28Nov deadline is looming large. Hurry, everybody.


Notes

(1) Endangered and Threatened Wildlife and Plants; Partial 90-day finding on a petition to list 404 species in the southeastern United States as endangered or threatened with critical habitat. Federal Register 76(187): 59836-62. [PDF]

(2) The 44-1 freshwater gastropod species listed in the 27Sept11 FWS finding are tabulated in the pdf document below. This document is modified and updated from a similar excel spreadsheet I posted on 18May11: [CBD-southeast-endangered.pdf]

(3) Megapetitions of the Old West [14July09]

(4) Megapetitions II: Armistice Day? [18May11]

(5) The best collection of documents related to the lengthy legal battles between the FWS, the CBD, and the WEG seems to be available from the FWS website:
Improving ESA Implementation

(6) Here's the announcement from the Center for Biological Diversity:
Historic Victory: 757 Species Closer to Protection

(7) Among the 30 species trimmed from CBD's original 404 was "Elimia" (or Leptoxis, or God-knows-what) melanoides from Alabama's Black Warrior River. That particular taxon has already been on the formal candidate list maintained by the FWS since 2006.

(8) FWS Virtual News Room - US Fish and Wildlife Service Finds 374 aquatic-dependent species may warrant endangered species act protection. [26Sept11]

Dispatches From The Viviparid Front

The notes, emails, and news items that our many friends send us from around the Americas often include interesting tidbits about the progress of freshwater gastropod invasions. But it occurs to me that it's been a few years now (1) since we've shared any of these updates with the group. So below is a sample from the old mailbag regarding the invasive viviparids, offered for general edification.

Citizens' Watch. Earlier this year our good friend Joan Jass of the Milwaukee Public Museum called my attention to a citizen-based invasive species monitoring program in Wisconsin. The Wisconsin "Citizen Lake Monitoring Network" (2) involves (the rather more ordinary) water quality and remote sensing components as well as a formal watch for a variety of invasive weeds, zeebs, the rusty crayfish, spiny waterfleas, jellyfish, Potamopyrgus (not arrived in Wisconsin as yet) and the invasive viviparids. Chapter 7 of the WI-CLMN Training Manual is a genuinely impressive 18-page "Mystery Snail Monitoring Protocol" (3) packed with good info on both Bellamya and Viviparus georgianus, which our good friend Pieter Johnson (4) seems to have been involved in developing.

Although many states apparently sponsor citizens' monitoring programs of their aquatic environments, it is my impression that invasive species components may be very unusual. Joan sent me links to the programs of Minnesota, Iowa, Illinois (5) and Michigan, but I didn't see invasive species specifically mentioned in any of them. And here in The South, the artificial impoundments into which viviparids have been introduced are inhabited almost nothing but invasive species, including us. It would be easier to tally the native species in South Carolina lakes, and monitor the invasive species by subtraction.

The image of the pretty watercolor above (6) comes to us from artist Aleta Karstad by way of Frederick Schueler, her husband and colleague at the Bishops Mills Natural History Center in Bishops Mills, Ontario.

Citizens Arise! A couple weeks ago our good friend Fred Schueler (7) reported to us that he had joined a small band of citizens from the vicinity of Winchester, Ontario, in an attempt to "control" a population of Bellamya chinensis inhabiting a three kilometer length of stream by dint of hand collection. Actually Fred tended to refer to this small tributary of the South Nation River as a "drain" in the extensive field notes he sent me, as it is managed by the municipality to drain land for agriculture. Although its large Bellamya population seems to have come to the attention of the South Nation Conservation Authority (which organized the event) only in 2010, subsequent conversations with the landowners suggest that the invasion itself may have occurred as much as 15 years ago.

The field conditions that Fred and his colleagues encountered were most trying. The accessible portions of the stream were apparently quite marshy or muddy, and a substantial fraction of the snail population apparently burrowing. The weather did not cooperate. Fred described the two-day event as "bound to be a token effort." Nevertheless, the team hand-collected, removed and measured a total of 1,260 adult B. chinensis from eight sites along the 3 km "drain." The fate of the Winchester 1,260 was still to be determined at last report. I suggested to Fred that he might mark at least some fraction of his catch, return them to the drain, and repeat the process next year. Fred was looking for recipes. We'll keep you posted.

ITIS Irritation. Last month I also swapped a couple emails with a Sea Grant outreach specialist at the NOAA Great Lakes Environmental Research Laboratory. It is the duty of this particular public servant to track invasive species for the Great Lakes region, and I was sent a couple photos of B. chinensis to confirm, which I was happy to do. So when I replied with my identification, I was informed that, "We are currently listing Chinese mystery snails as Cipangopaludina chinensis malleata (Reeve 1863). We use ITIS as our primary authority for nomenclature - ITIS does not accept the shift to Bellamya."

I certainly do understand why the Gubmint finds it expedient to maintain an "Integrated Taxonomic Information System," I really do. And I also understand why, once a name is assigned to a thing, they don't want to change it. And I understand that ITIS follows the Turgeon et al (1998) AFS Special Publication #26 (8), which in turn follows the freshwater gastropod names current in the 1980s, when Burch's work was published. But I hope our colleagues at ITIS don't go home at night and tell their children that mommy or daddy is a scientist. Because the names that evolutionary biologists assign to populations of organisms are scientific hypotheses, and to "not accept" a new hypothesis is worse than unscientific, it is anti-scientific.

Barbarians at the South Gate. Back in June of 2010 I got a nice email from our good friend Gabriela Cuezzo at the Universidad Nacional de Tucuma'n in Argentina. She reported that she had discovered a population of large snails that might be Bellamya japonica in the central Argentinian province of Cordoba, and as gastropods of the family Viviparidae are entirely absent from the native fauna of South America, she was anxious to have her identification confirmed. Her small shipment took over a month to arrive here in Charleston via "snail-mail," but when I unwrapped the specimens I was surprised to discover neither of the big Bellamya species that have spread over so much of North America, but rather a somewhat smaller-bodied viviparid I think is probably Bellamya (or Sinotaia) quadrata (above). Gabriella reported this invasion at the VIII CLAMA meeting in Puerto Madryn in June of 2011 (9).

I suppose it's only a matter of time until there is but one single, homogeneous, worldwide biota, zoned identically from pole to equator, mirrored north and south. When all the local faunas are outcompeted and extinct, our friends at ITIS should be pleased to find many fewer species to "not accept" research on.

Notes
(1) Our last news bulletin on viviparid invasion was "Bellamya (Cipangopaludina) News," way back on [6Oct05]

(2) Wisconsin Citizen Lake Monitoring Network
(3) All the chapters are conveniently downloadable as separates directly from the WI-CLMN publications page [here], including the "Chinese and Banded Mystery Snail" Chapter 7, which is indeed impressive, once you get beyond the sinistral stylommatophoran on the cover page.

(4) Pieter played a leading role in the research group who elucidated the "Community Consequences of Bellamya Invasion" [14Dec09].

(5) Actually, the Illinois Ecowatch Network website seems to have been taken down recently, and a lot of Minnesota links seem to be missing as well. State budgetary woes, perhaps? Minnesota does seem to fund Invasive Species Prevention "Grants and Partnerships," however.

(6) Karstad Biodiversity Paintings: Adventures in the Color of Canada [29Aug11]

(7) Fred Schueler seems to be a fellow-traveller in the blogosphere. He also made a guest appearance in Aydin Orstan's post "Cepaea nemoralis at Bishop's Mills." See Snail's Tales [24Aug11]

(8) To some extent, I blame myself for the Turgeon debacle. I vividly remember when the American Malacological Union was approached about collaborating with the AFS on the 1998 "Common and Scientific Names" of mollusks publication. I did not participate, largely because I thought it absurd for a bunch of PhD scientists to fabricate "common" names. But had I realized that AFS Special Publication #26 would become enshrined as the sacred list of all allowable names, scientific as well as common, for the entire American mollusk fauna forever, I would have done more than sit idly by. I would have fought the entire concept itself tooth and nail.

(9) VIII CLAMA - Congreso Latinoamericano de Malacologia 2011, Puerto Madryn, Argentina. Gabriella's abstract is on page 226 of the "Libro de Resumenes" available from the site.

Rhodacmea Ridotto

Editor's Note.  This essay was subsequently published as: Dillon, R.T., Jr. (2019b)  Rhodacmea ridotto.  Pp 149-155 in Freshwater Gastropods of North America Volume 2, Essays on the Pulmonates.  FWGNA Press, Charleston.

The headline news at the AMS meeting in Pittsburgh late last month was the rediscovery of two populations of the rare limpet genus Rhodacmea, together with a reawakening of our collective consciousness regarding this peculiar element of the North American freshwater gastropod fauna. A formal report by Diarmaid O’Foighil and his collaborators in Michigan, Alabama, and Kentucky was published on May 31 in PLos One (1).

In recent years we have often taken note of the excellent research on ancylid limpets issuing from our good friends in Ann Arbor: Diarmaid, Taehwan Lee, Jack Burch, and (until recently) Andrea Walther. Faithful readers will remember the columns we posted in 2007 and 2010 regarding their work on Laevapex and Ferrissia, respectively (2). And just as was the case with those latter genera, the best way to put the new Rhodacmea results into perspective is to back up to the 1963 monograph of another worker with Ann Arbor roots, Paul Basch (3).

Rhodacmea is the most distinctive of the North American ancylids, bearing a shell Basch described as “strangely indented” and a “peculiar” radula with heavy inner cusps as well as the usual (more delicate) outer ones. Basch asserted, “The genus in North America undoubtedly represents a branch of the basic Ancylus stock, related to European Ancylus fluviatilis,” a hypothesis that modern molecular data seem to bear out. He recognized three species: R. filosa (tall, ribby and thin - Basch's figure above), R. eliator (tall, smooth and robust - Basch's figure below), and R. hinkleyi (with a lower apex, not important for our story here). The historic ranges reviewed by Basch centered all three species in big rivers of the Alabama and Tennessee systems, although eliator was originally described from the Green River of Kentucky.

But by 1963 Basch observed,

“The genus is undoubtedly approaching extinction as more and more fast-flowing, larger streams and rivers in the southeastern United States are rendered unsuitable as habitats by dams and pollution… I have collected in dozens of streams in these areas and have located living Rhodacmea only in the Cahaba River near Helena, Alabama.”

Modern records are indeed very scarce (4). The IUCN Red List declared R. filosa extinct in 2000.

Seen in that light, the biggest news from Pittsburgh may have been the rediscovery of viable populations of Rhodacmea in Choccolocco Creek (a Coosa tributary about 100 km east of the Cahaba) by our colleague Paul Johnson, and in the Green River by our colleague Ryan Evans. These are valuable biodiversity resources, and well worthy of conservation.

The glad tidings have been somewhat tarnished, however, by their scientific treatment at the hands of our colleagues in Ann Arbor, which (I fear) expose the rather shabby undergarments of the harlequin we conservation biologists too often seem to play. For both in their AMS presentation this past month, and in their recently published paper, O’Foighil and his colleagues assert that all three of their Rhodacmea populations “merit specific status” separately.

Of course, historically all the freshwater limpet species have been recognized entirely by shell morphological criteria. On that basis, Basch identified the Cahaba population as R. eliator. And Anthony’s (1855) type locality for R. eliator was the Green River of Kentucky. That is why, as I understand it, a directed search was undertaken there. And the formal morphometric study published by O’Foighil and colleagues returned no significant difference between the Cahaba and Green River eliator populations.

The level of CO1 sequence divergence between Cahaba and Green is also small, when compared to values these same researchers have obtained among conspecific populations of Ferrissia and Laevapex. Judging from the scale bar on their CO1 gene tree (click for larger) the O’Foighil group found perhaps 5-6% sequence divergence among all haplotypes sampled from all three Rhodacmea populations – Cahaba, Green, and Choccolocco. Compare this to the divergence shown among Laevapex fuscus haplotypes – easily in the 10 - 13% range. So given both negligible morphological difference and negligible sequence divergence (5) between the Cahaba and Green River Rhodacmea populations, how can our colleagues assert that they represent different species?

The reasoning offered by O’Foighil et al. to support their three-species hypothesis pirouettes about the Choccolocco population, individuals from which apparently bear sufficient ribs on their shells to support their identification as R. filosa. Our colleagues seem deeply invested in the proposition that this population cannot be conspecific with the previously-known Cahaba population, issuing press releases trumpeting their rediscovery of a unique species in Choccolocco Creek believed extinct for 60 years (6). So since Choccolocco must be a different species from Cahaba (at less than 1% sequence divergence!), the Green population (at 6% divergence) must represent a third.

They further reason that the Green River population must be the true eliator (since that is the type locality) and Cahaba must be a cryptic species Basch did not recognize. The old name cahawbensis seems conveniently available for rescue from synonymy.

But regarding the plasticity of shell characters in freshwater limpets, I can do no better than quote our Ann Arbor colleagues themselves (7): “Shell shape and sculptural features … are unreliable phylogenetic indicators, and they presumably (8) encompass a large ecophenotypic component.” I will also note that the morphometric analysis around which this entire commedia dell' arte turns included just N=2 bona fide individuals from Choccolocco, combined with N=6 museum specimens from a fourth (extinct) population of the author’s own choosing. And does crediting shell characters when they split Choccolocco and Cahaba, but discounting them when they lump Cahaba and Green, seem a trifle disingenuous to anybody else?

Perhaps there is some more profound reason that our colleagues have recognized three species of Rhodacmea, where they have seen only single species in Laevapex and Ferrissia, given similar evidence? A cynic would note that it is easier to get funding for three endangered species than one. But knowing our colleagues as I do, I feel sure that their motivation was the finest – to maximize the likelihood that these populations, by whatever names they may be called, will be conserved into the future. Their ends do not, however, justify their means.


Notes

(1) O'Foighil, D. O., J. Li, T. Lee, P. Johnson, R. Evans, & J. B. Burch (2011) Conservation genetics of a critically endangered limpet genus and rediscovery of an extinct species. PLoS One 6 (5): e20496. [html]

(2) Phylogenetic sporting and the genus Laevapex [20July07]
Two species of Ferrissia [8Dec10]

(3) Basch, P. F. (1963) A review of the recent freshwater limpet snails of North America (Mollusca: Pulmonata). Bulletin of the Museum of Comparative Zoology 129: 399 - 461.

(4) Although there are 1978 collections of R. filosa from Choccolocco Creek in the Florida Museum of Natural History.

(5) I will resist the temptation to preach my "gene trees are not species trees" sermon here. But sinners should prayerfully consider my post of [15July08].

(6) The news seems to have been picked up by Science Daily in early June, and spread to a variety of web-based outlets serving the conservation community, such as terradaily.com, redorbit.com, and batangastoday.com. The headlines in all cases are to the effect that a "Snail Long Thought Extinct Isn't." The Green River population is not mentioned in any of these secondary reports.

(7) Walther, A., T. Lee, J. B. Burch, and D. O'Foighil. 2006. E Pluribus Unum: A phylogenetic and phylogeographic reassessment of Laevapex (Pulmonata: Ancylidae), a North American genus of freshwater limpets. Molecular Phylogenetics and Evolution, 40: 512.

(8) Presumption is not necessary here. I reviewed our common garden experiments with ancylid limpets in my post entitled, “Just One Species of Ferrissia.” [10June09]