The Mystery of the SRALP: A Twofold Quest!

Editor’s Notes – If you're just joining us.  This is the second installment in my 2013 series on the Snake River Physa controversy.  It won’t make any sense unless you back up and read my February installment first.  It might also help to read my essays of March 2008 and September 2010, but the most important thing is to read last month’s post, before trying to read this one.  I’m serious, I mean it.

This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Mystery of the SRALP: A Twofold Quest.  Pp 173 - 180 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

The rendezvous was set for 9:00 Sunday morning, September 19, 2010, at a gas station by the interstate near Burley, Idaho.  We were four biologists of strikingly different agendas, drawn together on a twofold quest.  And I suppose I should not have been surprised, but I was.

When I first suggested a field trip to the Minidoka Dam to Mr. Ryan Newman, my Bureau of Reclamation host, I had imagined that I would go alone.  I thought perhaps he’d call the staff on duty for me, maybe get somebody to open a gate on a Sunday morning, and I’d be fine.  I was pleased (of course) to discover that he was willing to accompany me as my native guide, and pleased again to see our good friend John Keebaugh’s email address on the CC line.  John works out of the Orma J Smith Museum at the College of Idaho in Caldwell, about 150-200 miles west, back near Boise.  But the fourth member of our party, chauffeured in by Mr. Newman as John Keebaugh and I stood chatting in the parking lot that morning, was a surprise.  Dr. John B. Burch, all the way from Ann Arbor.

Dillon, Burch & Keebaugh

My agenda on the Snake River that morning was simple – to test the hypothesis I first advanced in my essay of March 2008 [1].  Based on the observations of Rogers & Wethington [2], it seemed likely to me that Physa acuta, or some snail not immediately distinguishable from Physa acuta (which we are calling the Snake River acuta-like Physa, or “SRALP”) should inhabit the shallow backwaters downstream from Minidoka Dam.  This would be consistent with the greater hypothesis, that outliers on the margins of acuta-like populations may have colonized more rapid midstream environments of the Snake River, inducing the phenotype we identify as Physa natricina.

It materialized that my three colleagues, on the other hand, were bent on sampling the deeper waters for additional specimens bearing the natricina phenotype.  The rationale for this behavior escaped me, as the existence of small-bodied physid populations bearing wide apertures in the deeper Minidoka tailwaters had already been well-established by the heroic survey of Gates & Kerans, which prompted this field trip in the first place. One would think, if the little things were indeed elements of an endangered species, we would leave them alone.  But no.

John Keebaugh had brought a long-handled dipper with which, wading into the river waist deep and extending to full length, he was able to retrieve cobbles from some rather great depth.  Ryan Newman and Jack Burch sorted through trays of these dredgings, looking for physids.

Meanwhile, I enjoyed a fresh, sunny morning wading around in the Snake River shallows all by myself, looking for the sorts of ponds and protected backwater areas that one might think of as typical Physa acuta habitat.  And finding slick-rock nothing.

It turns out that the Snake River below Minidoka Dam is a really crappy habitat, for snails or indeed for macroinvertebrate benthos of any sort.  Our team visited three sites, from River Mile 675 just below the spillway to River Mile 670 at the Jackson Bridge.  And throughout that five mile stretch, it was my impression that river levels are terribly impacted by the generation schedule at the dam.  On the September day of our visit we found a couple vertical feet of cobble beach exposed, and I would estimate that the water levels regularly fall another 3-4 vertical feet below that.  So even wading knee deep and squinting as far as I could into the dark, roiling river, I probably couldn’t see to any bottom that hadn’t been dewatered last May, and wouldn’t be dewatered again come December.

I did find a few Physa gyrina in the shallows – mostly on sticks and organic debris – probably washed in from little side tributaries [3].  In fact, the only really nice snail population I saw all morning was the Physa gyrina in a seep near the base of the spillway [4].  But I found no acuta-like Physa in the Minidoka tailwaters [5].  That turned out to be a really, really crappy habitat.

So we ate lunch and I bid my colleagues adieu.  And I hopped back into my rental car and turned my attention toward a (rather poor) roadmap I found in the glove compartment.  And began planning a blitzkrieg survey of the Snake River further downstream, on my return trip west, back toward Boise.

Snake R from the US93 Bridge

At this point a brief orientation might be helpful.  The Snake River runs east to west like a giant smiley-face across the bottom of Idaho, then north along the Oregon border through Hells Canyon to join the Columbia River at Kennewick, Washington, there designated “Snake River Mile 0.”  So Minidoka Dam is in eastern Idaho, at river mile RM 675.

Rogers & Wethington [2] never promised us any Physa acuta as high as RM 675.  They reported that their sample of 211 physids collected between RM 573 and 340 contained 94% of the “Physa acuta group.”  Nor did Dwight Taylor list any localities upstream as high as Minidoka County in his original description of Physa natricina [6].  His natricina localities were in Gooding, Elmore, and Owyhee counties, roughly RM 571 – 525.

It looked to me as though the Milner Dam (located at RM 639) backed the Snake River up almost to the Jackson Bridge, where I sat parked early that Sunday afternoon.  So I rather arbitrarily set my course for the US 93 bridge near Twin Falls, further downstream at RM 611.  The river turned out to be inaccessible from the US 93 bridge, but I was able to follow signs down to a public access at the Magic Valley Hatchery, RM 600.

The Snake River at RM 600 had taken an entirely different character from the flashy, sterile thing I’d waded around in all morning.  It was broad and warm and shallow and rich [7].  And the rocks on the quiet margins were covered with SRALP-snails, indistinguishable to my eye from Physa acuta.  It didn’t take me ten minutes to squat down and collect at least 25 – 30 individuals in a drinking cup, which I resolved to carry with me to the meeting in Boise Monday morning.

Thousand Springs area

Then I got back into my rental car and continued driving east, enjoying the lovely weather and the countryside all quite exotic to my eastern eyes.   I made three additional stops, all brief: at the Owsley Riverfront Park (RM 582), at Bliss (RM 565) and at Glenns Ferry (RM 538), just as the sun was setting.  The river looked rich at all these spots, with a nice, diverse pulmonate fauna.  The population of Potamopyrgus (“New Zealand Mud Snails”) at Owsley was strikingly dimorphic, which was interesting [8].  And I enjoyed the big Fluminicola population at Bliss, the first I’d ever seen on the hoof.  And at all three spots I found SRALP-snails at least moderately common.  I picked up a few at each site and kept going.  I saw no Physa gyrina anywhere in my quick tour of the Snake River between RM 600 and RM 538 at all.

Back in Boise that night I slept soundly, my sample of SRALP crawling peacefully around the drinking cup at my bedside.  Surely, I thought, everybody at the big Bureau of Reclamation meeting on the morrow would see the importance of these snails to the answer of our ultimate question.  Does the strange little physid population in the Minidoka tailwaters that Gates & Kerans refer to “Physa natricina” indeed represent an endangered species?  Or might they be ecophenotypic variants of an otherwise common species, nevertheless endemic to the Snake/Columbia system?  Or might the Gates & Kerans sample simply constitute 274 ecophenotypic variants of the invasive pest Physa acuta, found everywhere on six continents?

How naïve could I be?  Join us again next time, for … Dixie-Cup Showdown!

  

Notes

[1] Red Flags, Water Resources, and Physa natricina [12Mar08]

[2] Rogers, D. C. & A. R. Wethington (2007).  Physa natricina Taylor 1988, junior synonym of Physa acuta Draparnaud, 1805 (Pulmonata: Physidae)  Zootaxa 1662: 45-51.

[3] To be as complete as possible.  I did collect approximately 15 - 20 juvenile and subadult Physa from the Minidoka tailwaters that I thought, on the morning of 19Sept10, might be Physa acuta.  I brought them home with me to Charleston, reared them to adulthood, and then dissected them.  Nope, they were all Physa gyrina.

[4] One of the strongest memories I have from my very brief introduction to the Minidoka tailwaters on a bitterly cold morning in December of 2005 was the high density of Potamopyrgus.  But on my return visit in September of 2010 I found exactly N=0 in several hours of effort.  The river levels were significantly higher in 2010, so it’s possible that I simply missed them.  Or has there been a flush/crash?

[5] So my hypothesis of 3/2008 was incorrect.  Physa gyrina seems to be washing into the shallows below Minidoka Dam, not Physa acuta.  My new hypothesis is that the little population of snails that Gates & Kerans are calling “Physa natricina” is the relict of a much larger acuta-like population comparable to those inhabiting the Snake River further downstream, but now extinguished from the shallows by operations at the dam.

[6] Taylor, D. W. (1988)  New species of Physa (Gastropoda: Hygrophila) from the western United States.  Malacological Review 221: 43-79.

[7] Although similar in outward appearances, P. acuta and P. gyrina have diverged strikingly in their life history adaptation.  Populations of P. acuta are weedy or “ruderal” – their rapid growth, quick maturity and high reproductive output (relative to body mass) adapted to exploit rich, although often unpredictable habitats.  Physa gyrina are more stress-tolerant (like a cactus), adapted to nutrient poor but nevertheless predictable habitats.  See my book (Dillon 2000) pp 131-136 and Fig 8.10 for more.  In southern Idaho, these life history differences seem to be reflected in the distributions of the two species – acuta in the main river (further downstream) and gyrina in the tributaries.

[8] The presence of two strikingly different shell forms in a single Potamopyrgus population would seem to suggest sexual reproduction.  The Snake River gastropod fauna really does offer a wealth of opportunity for important scientific research, if serious scientists could get beyond all the politics and confusion.  Such a shame.

The Mystery of the SRALP: A Bidding...

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Mystery of the SRALP: A Bidding...  Pp 165 - 171 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

The invitation arrived by email on 19Aug2010.  Mr Ryan Newman of the US Bureau of Reclamation (USBR) was curious to know whether I might be available to join a working group convening in Boise to review a report by K. Gates & B. Kerans entitled, “Snake River Physa, Physa (Haitia) natricina, survey and study.”  And so began one of the greater malacological adventures of my life, professional or otherwise.

Faithful readers may remember my post of March 2008 regarding the federally-endangered Physa natricina [1].  Described by Dwight Taylor (1988) in one move of an (ultimately successful) effort to thwart the impoundment of the last free-flowing section of the Snake River in southern Idaho, the species was for many years a phantom – no precise localities known, even the type specimens lost.  Its habitat seemed to be unique among physids, “on boulders in the deepest accessible portion of the Snake River near rapid margins” [2].  The adults were unusually small-bodied (shell length “5.4 – 6.9” mm), bearing an unusually wide aperture.  See note [3] for more about the photo below.

Taylor went to some length to distinguish his Physa natricina from Physa gyrina – the former having a one-part penial sheath (“type-c”) and the latter a two-part sheath (“type-b”).  But in late 2007 Rogers and Wethington [4] pointed out that Taylor’s anatomical description was not sufficient to distinguish P. natricina from the worldwide invasive P. acuta*, another type-c physid apparently common in the shallows throughout most of the Snake.  Since stunted size and an odd aperture might simply reflect ecophenotypic responses to life in a habitat to which physids are marginally suited at best, Rogers and Wethington synonymized Taylor’s nomen natricina under P. acuta.  One might think this would end the matter.

But a controversy every bit as political as that which prompted the 1992 listing of Physa natricina had been simmering for some years in the Snake River tailwaters below Minidoka Dam, 20 miles upstream (NE) of Burley.  There macrobenthic surveys conducted in the mid-1990s by biologists working for the Bureau of Reclamation had returned small, oddly-shaped physids identified by consultants in 2004 as Physa natricina.  This prompted the US Fish & Wildlife Service to issue a “Biological Opinion” in March of 2005 [5] affecting the USBR’s management [6] of Minidoka Dam.  So in August of 2005 the USBR commissioned a study [7], which by August of 2010 had yielded fruit.  And I was being invited to review the result.

The 87-page Gates & Kerans report attached to Mr. Newman’s bidding comprised three sections – a survey, a morphological study, and a DNA sequence study.  The survey section spun a ripping-good yarn of suction dredges and tethered scuba divers, ultimately triumphing in the recovery of a remarkable 274 small, oddly-shaped type-c physids from the roiling waters of the Snake River below Minidoka Dam.  The second section reported a conventional study of the shell and anatomy of six of these small snails, featuring a photo of a couple living individuals (“courtesy of John B. Burch”).  And the third section, contributed by collaborators at both Montana State and the University of Michigan, reported an average 19.7% mtDNA sequence divergence between approximately 30 of these little snails (combined over both labs) and a sample of Physa gyrina.

And here’s the headline.  Gates &  Kerans reported an eye-popping 17.1% average sequence divergence between their sample of small, oddly-shaped type-c physids and Physa acuta sequences retrieved from Genbank.

But alas.  Gates & Kerans seemed entirely ignorant of (or worse, dismissive of?) the Rogers and Wethington report of Physa acuta* in the Snake River.  And the nearest P. acuta sequence available for comparison in GenBank had been sampled 500 km NE of the Minidoka Dam, on the other side of the Rocky Mountains in Wyoming.  And Gates & Kerans had not (apparently) felt called to sample their own.

Granted, the Rogers and Wethington study was not published until after the 2007 field season, by which time two years of data were already in the can.  But it seemed to me that, as soon as the existence of P. acuta* in the Snake River became known, those populations became the only appropriate control for the study of P. natricina, not P. acuta sampled across the continental divide 500 km northeast, and certainly not P. gyrina. The relevant morphological comparison would be between the population of small, oddly-shaped type-c Physa at mid-river in the Snake and equally small P. acuta* sampled from its shallows.  Gates and Kerans needed DNA samples from Snake River acuta*; neither Snake River gyrina nor Wyoming P. acuta were germane.

At this point in our malacological adventure I find it convenient to introduce a new term, “Snake River acuta-like Physa,” or SRALP for short.  And request that my readership mentally replace all five instances of the binomen "Physa acuta” marked with asterisks above with “SRALP.”  And find it necessary to reverse the flow of my narrative once again, back to an essay I wrote in September, 2010 [8].

That particular essay was prompted by the de-listing of Valvata utahensis and Pyrgulopsis robusta, two of the other four freshwater gastropod species politically listed in 1992 to block the Snake River impoundment.  In that 2010 essay I made reference to what seemed like a logical progression of three hypotheses – narrow endemic, regional endemic, and nonendemic – and lamented how natural resource politics had for 20 years short-circuited the (otherwise orderly) examination of all three.  And toward the end of that essay I pointed out that, in the case of Physa natricina, nobody seems to have given any study to “Hypothesis #2 (of 3)” at all.

The Gates & Kerans report was on my desk at the time I wrote my 2010 essay, and the timing was not a coincidence.  Does the Gates & Kerans sample of 274 small type-c Physa come from a narrowly endemic species, restricted to “boulders in the deepest accessible portion of the Snake River,” best identified as Physa natricina?  Or perhaps those 274 snails are simply ecophenotypic variants of the nonendemic P. acuta, otherwise common in the Snake River backwaters and elsewhere throughout the world?  Or might the Snake River be home to a regional endemic – locally common and practically indistinguishable from acuta in the calm backwaters, but rare, stunted and misshapen in the rapids?  The names concolor (Haldeman 1843) and columbiana (Hemphill 1890) are already in the literature for this second (of the three) possibilities. 

The answer to these questions and more would rest in the SRALP.  What exactly is that population of type-c physids reported common in the Snake River by Rogers and Wethington?  And what might their relationship be to the 274 odd little physids heroically retrieved by Gates & Kerans?  Tune in next time, as we journey to southern Idaho, on a quest!

Notes

[1] Red flags, Water Resources, and Physa natricina [12Mar08]

[2]  The “deepest accessible portion” quote comes from Taylor’s (1982) “Status Report on Snake River Physa Snail” (USFWS, Portland).  Taylor’s formal description of 1988 did not include habitat notes of any sort, oddly.

[3] The shell labelled "natricina" was dead-collected in the "drift" on one of the rocky beaches below the Minidoka Dam on 19Sept10.  Its collector was John Keebaugh, who identified it and made a gift of it to me.  I myself had collected the P. gyrina from a seep near the Minidoka Dam spillway earlier that morning.  And I also collected the individual labelled "SRALP" (Snake River acuta-like Physa) later that same day from the Snake River at Owsley (RM 582).  More in our next installment.

[4] Rogers, D. C. & A. R. Wethington (2007)  Physa natricina Taylor 1988, junior synonym of Physa acuta Draparnaud, 1805 (Pulmonata: Physidae).  Zootaxa 1662: 45 – 51.

[5] USFWS (2005)  Biological Opinion for Bureau of Reclamation Operations and Maintenance in the Snake River Basin Above Brownlee Reservoir.  This and all the other documents regarding the 2004-05 Minidoka controversy (including the implementation plan for a Physa study) are available from the Bureau of Reclamation here: [USBR 2004 Biological Assessment].

[6]  All the 2005 fussing (that came to my ears, anyway) focused on the annual schedule of water release from the Minidoka Dam, the FWS pressing for something closer to natural flow.  It also turns out that the USBR had been studying the complete replacement of the Minidoka Dam spillway since at least 2000, although I didn’t hear about that element of the controversy until 2010.  Here is the USBR page with all the documents relating to the spillway replacement: [USBR Spillway Replacement].

[7] To be as complete and fair as possible.  My first visit to Minidoka Dam came in December of 2005 as a member of a “Snake River Physa Technical Team” convened by the Bureau of Reclamation to provide recommendations for their study (documents at Note 5 above).  At the time, there was real concern that even if any small, misshapen type-c physids might be recovered from the Minidoka tailwaters, nobody could positively confirm their identity as P. natricina.  And I had not heard another word about the project as of 12Mar08, hence the reference to “a day which never arrived” in my 2008 blog post. 

But (in fact) the Gates & Kerens study was already into its third year by the spring of 2008.  I was invited to a second meeting of the Snake River Physa Technical Team on 1May2008, although not offered any funding to get me there.  So I told Mr. Newman that “if I happen to be in Boise on May 1, I’ll drop by.”  I would nevertheless have been happy to read a written progress report, had Mr. Newman offered one in 2008, which he did not.  Thus the desirability of standards and controls in scientific investigation was not called to the attention of Gates & Kerans until the fall of 2010, by which time there seems to have been little opportunity for a remedy.

[8] Valvata utahensis and Hypothesis #2 (of 3)  [14Sept10]

The Clean Water Act at 40

Editor’s Note. This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Clean Water Act at 40.  Pp 201 - 205 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

I was born and raised in the Shenandoah Valley of Virginia, in a geographical oddity known as Waynesboro, 100 miles from everywhere.  But near enough, by happy fortune, to the South River (a tributary of the South Fork Shenandoah) as it cascaded freshly down from the Blue Ridge, and slowed upon entry into the verdant valley below [1].  And I spent some of the happiest days of my youth swimming, fishing, rafting, and grabbing everything slick and squirmy I could grab out of those gentle waters, from snakes and turtles to crayfish, bugs, and (of course!) snails.

In the riffles the benthic macrofauna was dominated by the pleurocerid Leptoxis carinata, with Physa common in the pools, limpets occasional and Helisoma anceps rare.  I remember being frustrated, even at the age of twelve, that I could not identify the freshwater snails of the South River.  I had a tremendous infatuation with the natural world around me, and could find guidebooks to help with the birds and reptiles, the trees and the wildflowers, and most shells – certainly the marine ones.  But not the freshwater snails.

In any case, the economy of Waynesboro was not as agricultural as I have made it sound above.  During the 1920’s two major textile-related plants joined a number of smaller factories already humming in the town – DuPont (manufacturing acetate fibers such as nylon, orlon & lycra) and Crompton (corduroy, velveteen & nylon velvets).  The attractions of this otherwise rural setting included cheap land, an eager work force, good rail transport, and (alas!) the South River to dump crap into.

The DuPont and Crompton plants (and several others, to be fair) stretched by the river for about a mile along the east side of town.  DuPont discharged large quantities of elemental mercury in among a witch’s brew of other chemical wastes generated as a consequence of routine manufacturing processes, over quite a number of years.  The several Waynesboro plants also featured very tall smokestacks that dumped huge amounts of black smoke into the sky.  I didn’t like it – nobody did.  But waste seemed like an inevitable consequence of economic prosperity [Photo below, Note 2].

By now you will have gathered that The Dillons lived upstream from the DuPont plant.  My friends and I occasionally rafted inner tubes a mile or so downstream to the Hicks Bridge, at the south entrance of the plant.  I don’t remember any signs specifically warning us of hazardous conditions further downstream – I think this was generally understood.  But in any case, had I ventured to gather any personal observations regarding the benthic macrofauna of the South River below the Hicks Bridge at any time in my young life, my mother would have found out quite promptly, which would have been hazardous enough, to my backside.

The Clean Water Act was signed into law on October 18, 1972.  I was a senior in high school by that time, and the next summer off to college at Virginia Tech, never to live in Waynesboro again.  Although my wife and I still have family in the area, I have lost that intimate connection I developed with the South River in my youth, carried away by other rivers less gentle.

The rebirth of the river downstream from the Waynesboro plants, in my absence, has been astonishing.  Mercury contamination was discovered in fish samples taken from the South River in 1976, precipitating a legal battle between DuPont and the state ultimately resolved in 1984.  As part of the settlement DuPont agreed to fund a “South River Science Team” [3] to serve as a focal point for technical and scientific issues concerning mercury contamination.  By 1989, the water quality had improved to such an extent that the state began stocking the South River at Waynesboro with brown and rainbow trout.  Waynesboro is now home to two annual celebrations of the South River, the Virginia Flyfishing Festival and the Waynesboro “Riverfest” [4].

Last summer I launched my kayak at the Apple Acres bridge near my childhood home and paddled through the entire City of Waynesboro, passing the DuPont site and the sites of several other industries only slightly less spectacular [5], emerging to call my brother-in-law at Bridge Avenue, about five miles downstream.  The most memorable features of my trip were the fly fishermen quietly angling in the shadows of the industrial smokestacks. 

The river looked pristine to casual inspection – Leptoxis carinata uniformly abundant through the river section I paddled.  Downstream from Waynesboro I pulled out and collected six species: Leptoxis, Physa acuta, Ferrissia fragilis, Helisoma anceps, H. trivolvis and Lymnaea humilis.  So in addition to the four species that have likely recolonized from upstream refugia, we seem to have added two species from downstream.  The freshwater gastropod fauna of the South River is today indistinguishable from that of any other similar-sized river in the upper Shenandoah Valley.

The Clean Water Act worked.  Sometimes I fear that the environmental community has earned a reputation for shrillness – always focusing on impending disaster, prophesying the end of the world.  It might help our credibility a bit if we acknowledged the real successes of the last 40-50 years and admitted, as bad as things might look today, we have seen worse.

This past summer I spent a couple weeks surveying the freshwater gastropods of New Jersey.  So prior to my departure I mapped a grid of sample sites to cover the various physiographic regions and drainages of The Garden State, mixing lotic and lentic habitats, large and small.  I paid attention to access, of course, preferring boat ramps, parks, and public spaces if possible.  Water quality concerns did not, however, enter my mind.

And so the afternoon of September 11, 2012 found me at a public park on the bank of the Raritan River in Manville, NJ.  The water was clear, apparently clean, and inviting.  The luxuriant macrobenthic fauna included 11 gastropod species, making it the second-richest site I was to visit that entire week.  Only a subsequent conversation with a passing fisherman reminded me of the history of that place, the site of the former Johns-Manville manufacturing facilities for asbestos insulation [6].

Happy Birthday, Clean Water Act.  And keep up the good work!

Notes

[1] The black & white photo above is a 1966 image of the South River as it enters Waynesboro.  That’s the old “Apple Acres” bridge in the background.  Scanned from Massie, E.S. and C. Skinner (2009)  Images of America: Waynesboro.  Arcadia Publishing.

[2] The South River runs around the right edge of this photo, from top to bottom.  The DuPont plant is featured in the middle of the photo (on the right descending bank) with the Crompton-Shenandoah plant shown at right, on the left descending bank.  This photo from the South River Science Team site, see note [3].

[3] South River Science Team [html]

[4] Waynesboro Riverfest [html]

The Virginia Flyfishing Festival [html]

[5] The Crompton plant went out of business in 1984, and has now largely been demolished.  DuPont sold its Waynesboro plant to the InVista Corporation a few years ago, and manufacturing operations continue at a reduced scale.

[6] I don’t have any independent knowledge of the Johns-Manville situation on the Raritan River in New Jersey, but here’s a link to the Wikipedia entry [html].

On Getting Clappia in Tennessee

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019c) On getting Clappia in Tennessee.  Pp 199 - 204 in The Freshwater Gastropods of North America Volume 3, Essays on the Prosobranchs.  FWGNA Press, Charleston.

The Powell River is one of my favorite places on Earth.  Running gently through a rich, narrow valley from southwest Virginia into East Tennessee, the Powell is home to about 17 species of freshwater gastropods, and perhaps twice that number of unionid mussels.  I first dipped a boot toe into those magical waters in the summer of 1975, as an hourly employee of the TVA working on mussel surveys, and have returned many times since.  I always see something new.

The Powell as it flows south into Tennessee is choked with pleurocerid snails – Leptoxis, Io, and three species of Pleurocera jostle each other for every square millimeter of benthic habitat.  This actually makes gathering observations on any other freshwater gastropod species extra-challenging.  As much as I love pleurocerids, I sometimes find myself wishing that they would all disappear for about an hour, so I could find anything else.

So I patted myself on the back in the summer of 2007 when I was able to confirm a population of Somatogyrus parvulus in the Powell River (marked “S” in the figure below).  Adult Somatogyrus are essentially indistinguishable from juvenile Leptoxis in the field (“L”), unless held up to close examination.  Their habitat was an important clue for me standing knee deep at midstream – I noticed a few suspicious little snails crouched Somatogyrus-like under rocks, when most of the Leptoxis population was grazing on top.

Then in 2008 I found a couple individuals of a second, more mysterious hydrobiid species in the Powell (C, below).  Again, they were mixed with a high density of Leptoxis, but this second population was more associated with woody debris in marginal pools than rocks at midstream.  Initially I thought they might be Amnicola (A), which does range through East Tennessee drainages, although not as commonly encountered as in Ohio drainages further north.  But back in the lab, they simply did not look like Amnicola.  I recorded them as “Birgella” in my database, which didn’t look right either, because the mystery snails were too small, and figured to come back to them in the future.

In 2010 I found samples of the same mysterious hydrobiid (C) at two sites in the upper Sequatchie River, another lovely mid-sized tributary of the Tennessee about 250 km SW of the Powell.  The Sequatchie also boasts a wonderfully diverse fauna of freshwater mollusks – certainly including Amnicola as well as a dense population of Leptoxis.  And again, to recover a completely vanilla 3 mm prosobranch gastropod from the waters of the Sequatchie that is neither a juvenile Leptoxis nor an Amnicola required something akin to divine intervention.  And once again, I labeled the mysterious little snails Birgella-with-a-question-mark and set them aside for future study, really rather distracted by the other 37 species of freshwater gastropods in the upper Tennessee drainage at the time.

So two years passed.  Then at the AMS meeting this past June I ran into my old buddy Bob Hershler, and he agreed to take a look at my (now three) samples of mysterious East Tennessee hydrobiid, and together we sorted the situation out. 

Bob confirmed a simple, unlobed “lithoglyphine” penial morphology for the mystery populations, firmly ruling out Birgella and Amnicola, and suggested Somatogyrus.  But Somatogyrus are more heavily-shelled and found midstream – witness the population of S. parvulus in the Powell River rapids not two meters from the marginal pool favored by our mystery species. The mystery hydrobiids bear a lighter, slightly more inflated shell with an umbilicus.  A Somatogyrus with an umbilicus?  Does that ring any bells?

Last month we reviewed the life and work of Bryant Walker (1856-1936), touching at some length on Walker’s research interest in the hydrobiid genus Somatogyrus [1].  Attentive readers may recall that between 1904 and 1909 Walker described 22 species of Somatogyrus, including 21 that were indistinguishable and one that looked different.  That different one, “remarkable for its round, deep umbilicus,” Walker removed to a new genus Clappia in 1909 [2].

Clappia umbilicata was originally described from the Coosa River of Alabama, and has not subsequently been collected elsewhere.  In 1965 Bill Clench reported an additional population of Clappia inhabiting a tributary of the Coosa River perhaps 50 km west of the type locality of C. umbilicata, which he described as Clappia cahabensis, honoring the strict one-drainage-per-species rule enforced throughout the Mobile Basin [3].

But the sad fate of the Mobile Basin gastropod fauna will be well known to most of my readership [4].  Thompson based his 1984 review of the lithoglyphine hydrobiids on a museum lot of Clappia, considering C. umbilicata "apparently" extinct and opining that C. cahabensis "may also be extinct" [5].  Both species were more recently listed as extinct by Lydeard & Mayden [6] and designated as such on the IUCN Redlist.  Our colleague Stephanie Clark enjoyed 15 minutes of fame for rediscovering C. cahabensis alive back in 2005 [7].

Now it has become apparent that the range of Clappia extends well beyond Alabama, to include at least two mid-sized rivers in East Tennessee [8]. And given how lightly the freshwater gastropods of Tennessee have been surveyed, and how difficult such diminutive hydrobiids may be to find in the high densities of pleurocerids that characterize the entire region, it seems quite likely that additional Clappia populations yet remain undiscovered.

We know less about the freshwater gastropod fauna of some parts of the United States than we do about the surface of Mars.  At this writing NASA’s “Curiosity Rover” is firing laser beams at the Martian surface [9] and transmitting data through 100 million kilometers of space to rooms-full of the world’s greatest engineers, at a mission cost of $2.5 billion, delivered.  NASA scientists know what they don't know.

But it seems possible that I may be the first person ever to hold those little snails in my hand – not the juvenile Leptoxis, not the Amnicola, not the Somatogyrus, not the Birgella - the other little 3 mm snail with the vanilla shell and the vanilla penis in the organic debris in the quiet backwaters of the Powell River as it flows into East Tennessee.  Nobody knows what we don't know about North American freshwater snails.

I do not begrudge NASA its $2.5 billion budget [10].  I would simply like to point out that we do not need to travel 100 million km to dip our boot toes into the magical waters of the unknown.

Notes

[1] Bryant Walker's Sense of Fairness [9Nov12]

[2] Walker, B.  (1909)  New Amnicolidae from Alabama.  Nautilus 22: 85-90.

[3] Clench, W. J. (1965)  A new species of Clappia from Alabama.  Nautilus 79: 33-34.  The primary difference between Walker's C. umbilicata and Clench's C. cahabensis seems to be body color, black for the former and white for the latter.  The mantles of the Tennessee populations do (generally) seem to bear black pigmentation.

[4]  For references on the conservation status of the Mobile Basin gastropod fauna see:

• Influential publications in freshwater gastropod conservation [3May10]
• Mobile Basin I: Two pleurocerids proposed for listing [24Aug09]

[5]  Thompson, F. G. (1984)  North American freshwater snail genera of the hydrobiid subfamily Lithoglyphinae.  Malacologia 25: 109-141.

[6] Lydeard, C & R. L. Mayden (1995) A diverse and endangered aquatic ecosystem of the southeast United States.  Conservation Biology 9: 800-805.

[7] Ivory-billed Freshwater Gastropods [9May05]

[8] A distribution map is available from the new Clappia umbilicata page on the FWGNA site: [Clappia umbilicata]

[9] Since 1898 there has been a narrative in western culture featuring an invasion by Martians, often involving robotic landers and death rays.  So now it materializes that NASA has mounted a laser gun on our most recent Martian Rover.  Apparently we kicked all the Nazi ass we can find, and kicked all the Commie ass we can find, and now we're up in space, kicking little green Martian ass.  USA! USA!

[10] This is because I cannot imagine any scenario where the subtraction of a single dollar from the NASA budget might yield even a penny for any funding source to which I might conceivably apply.  I don't understand money, at all.  But I think that funding for space research may be motivated by a combination of national pride, military paranoia, and Buck Rogers romanticism.  Although NASA takes the money and does some science with it (among other things), NASA's appeal is not primarily, or secondarily, or even tertiarily scientific.  But I do not understand money, at all.

Bryant Walker's Sense of Fairness

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019c) Bryant Walker's sense of fairness.  Pp 191 - 198 in The Freshwater Gastropods of North America Volume 3, Essays on the Prosobranchs.  FWGNA Press, Charleston.

Bryant Walker was a lawyer.  It is difficult for us to comprehend, looking back on his distinguished career in malacology, which extended over 50 years and 155 publications, that he never held a formal position at any scholarly institution.  And that the second word under Walker’s entry in R. Tucker Abbott’s Directory of American Malacologists [1], after the word lawyer, is “amateur.”

He was born in Detroit in 1856 and died in Detroit in 1936, and will ever be linked most closely with his alma mater, the University of Michigan.  Indeed 25 of Walker’s 155 publications were regional surveys – directed toward the molluscan fauna of the Wolverine State [2].  But he corresponded widely throughout North America, developing especially close friendships with Ortmann in Pittsburgh, Pilsbry in Philadelphia, and such prominent collectors as J. H. Ferriss, A. A. Hinkley, and H. H. Smith.  And he became an international authority on freshwater limpets, publishing important contributions on the ancylids of South America and Africa, as well as revising our own continental fauna here at home [3].

According to Calvin Goodrich [4, 5], whom he recruited to the University of Michigan in 1929, the first entry in Walker’s personal catalog of shells was “made in the back part of a university notebook on physics” in 1874, while he was yet an undergraduate.  He published his first paper in the year of his graduation from Michigan with an A. B. in 1876, and his second paper the year he graduated from the Michigan Law School in 1879.  Thereafter he entered private practice as an attorney in Detroit, turning his “three-storied, high ceilinged, mansard-roofed house” into a museum, “the ground floor dedicated to gastropods, the upper to bivalves.”  Again according to Goodrich, “When the collection was moved in June [of 1936] to the University of Michigan at Ann Arbor, a great pile of boxed shells was discovered in the attic rooms, others on shelves in the basement where some were partly buried under coal.”

Walker’s research interests favored the freshwater gastropods (56 papers), but did not neglect the unionid mussels (29 papers).  In his day he was probably best known for the “Mollusca” chapter he contributed to the first (1918) edition of Ward & Whipple’s influential “Freshwater Biology.”  He expanded that work into a stand-alone “Synopsis of the Classification of the Freshwater Mollusca of North America,” augmented it with “A catalog of the more recently described species, with notes,” and published it as a 213-page “Miscellaneous Publication” of the University of Michigan [6].

I keep a reprint of Walker’s 1918 “Miscellaneous Publication” on the shelf next to my desk, and refer to it often.  The work grew from an extensive system of note cards that he compiled for his personal use over many years, recording not just the descriptions of new species as they were published, but indeed any note or comment regarding any species of North American freshwater mollusk to appear in the literature over several decades.  In cases such as the Physidae, where no monographic treatment was published between Binney’s of 1865 and George Te’s of 1975, Walker’s “Miscellaneous Publication” provides an indispensable bridge from the ancient to the merely old.

Bryant Walker had a lawyer’s sense of fairness.  As the 20^th century dawned, the larger and showier freshwater gastropods, such as the lymnaeids, the planorbids, and especially the pleurocerids, had all received more than their fair share of attention.  Thus he focused his research efforts on the smaller and plainer taxa – the hydrobiids, the valvatids, and especially the ancylid limpets.

Among the hydrobiids, the plainest genus is arguably Somatogyrus, which bears a relatively heavy but otherwise nondescript shell and a simple penis.  All the other hydrobiid groups – the Amnicolines, the Nymphophilines, the Fontigentines – have an elaborate penial morphology with accessory lobes and glandular crests and extra ducts and were already, by Walker’s day, split into scores of regional species.  It did not seem fair to Walker that there should be dozens of species of Amnicola in New England, and hundreds of species of pleurocerids in Alabama, but just four species of Somatogyrus, simply because they were so plain.

So in 1904 he described 11 new species of Somatogyrus, including the regional taxa S. pennsylvanicus, S. virginicus, and S. georgianus, as well as 8 species from the Mobile Basin of Alabama [7].  And between 1906 and 1915 he described 14 additional species, most from the Tennessee River and its tributaries in North Alabama [8, 9, 10].

Almost all 25 of these species were, quite plainly speaking, indistinguishable.  Walker described the shell of Somatogyrus virginicus, for example, as “small, globosely conic, and imperforate,” and that of S. pennsylvanicus as “small, obtusely conic, narrowly umbilicate, sometimes imperforate [7].”  The only exception was his Somatogyrus umbilicatus from the Coosa River of Alabama, about which Walker enthused, “This species is remarkable for its depressed, valvata-like form and round, deep umbilicus, which readily differentiates it from all other known species of the genus.”

By 1909 it was beginning to seem unfair to Walker that the genus Somatogyrus should include 21 indistinguishable species (by that point, see note 11) and one that looked different.  So he removed his S. umbilicatus to a separate genus, Clappia, and redescribed it as Clappia clappi, to doubly-ingratiate himself with G. H. Clapp, then curator of mollusks at Harvard’s MCZ [Plate above, see ref 9].  The genus remains valid to this day, although the specific nomen “clappi” was dead aborning [12].

It was Calvin Goodrich’s opinion, however, that Walker’s 25 papers on the Ancylidae “will probably stand as his best work.”  While essentially all of the 16 species-level ancylid taxa he described from North American waters have now disappeared into synonymy [13], Walker's genera Ferrissia, Laevapex, and Rhodacmea survive to this day, albeit with approximately one species each [14].

But with the advantage of 100 years’ perspective, I would suggest that Bryant Walker’s best work was “Malacology at the University of Michigan.”  If there was any interest in mollusks at Ann Arbor prior to Walker, I can find no evidence of it [15].  But after Walker came Goodrich [5], and after Goodrich came van der Schalie, and under van der Schalie trained W. J. Clench, A. R. Solem, P. F. Basch, J. B. Burch, W. H. Heard, and many, many others, including (full disclosure) my own Ph.D. advisor, G. M. Davis. 

Absent the Malacology Department at the UMMZ, the landscape of our discipline in America today would present a far more desolate aspect.  Although I have never seen him accorded the honor, let’s bestow upon Mr. Bryant Walker, lawyer, amateur, the title “Father of Malacology at Michigan,” shall we?  It’s only fair.

Notes

[1] Abbot, R. T. (1973)  American Malacologists.  Published by the author, Falls Church, Va.

[2] Goodrich, C. (1939) The scientific writings of Bryant Walker.  An annotated bibliography.  Occas. Pprs. Mus. Zool. Univ. Mich. 402: 1 - 28. This is also the source of the Walker portrait accompanying the post.

[3] Walker, B. (1917)  A revision of the classification of the North American patelliform Ancylidae, with descriptions of new species.  Nautilus 31: 1 - 10.

[4]  All the anecdotes in paragraph three of this essay come from a very sweet and personal obituary published by Goodrich (1936) in Nautilus 50: 59-64.

[5] Calvin Goodrich ranks very high on my list of professional heros, just behind Darwin, Mendel, and Morgan.  For my personal tribute, see:

• The Legacy of Calvin Goodrich [23Jan07]

[6] Walker, B. (1918)  A synopsis of the classification of the freshwater Mollusca of North America, North of Mexico, and a catalogue of the more recently described species, with notes.  Univ. Mich. Mus. Zool. Misc. Publ. 6: 1 - 213.

[7]  Walker, B. (1904)  New species of Somatogyrus.  Nautilus 17: 133 - 142.

[8] Walker. B. (1906)  New and little known species of Amnicolidae.  Nautilus 19: 97-100, 114-117.

[9] Walker, B. (1909)  New Amnicolidae from Alabama.  Nautilus 22: 85 - 90.  Walker's "Plate VI" shows Clappia "clappi" shell (1), operculum (4), and radula (7), along with various other Somatogyrus from Alabama.

[10] Walker, B. (1915) Apical characters in Somatogyrus with descriptions of three new species.  The Nautilus 29: 37 - 41, 49 - 53.

[11] Actually there were approximately 30 species of Somatogyrus by 1909, including 8 described by authors prior to Walker.

[12] The specific nomen "clappi" (Walker 1909) immediately became a junior synonym of umbilicata (Walker 1904).  How did the great H. A. Pilsbry, who edited The Nautilus from 1889 to 1958, let Walker make the rookie mistake of naming the same species twice?

[13] The only exception may be Rhodacmaea hinkleyi (Walker 1908), which even if it is distinct, is probably extinct.

[14] I have posted updates on all three of these genera in recent years:

• Phylogenetic sporting and the genus Laevapex [20July07]
• Two species of Ferrissia [8Dec10]
• Rhodacmaea Ridotto [8Aug11]

[15] The first curator of malacology at the University of Michigan was Miss Mina Winslow, whom Walker had some hand in “encouraging” to the job, according to van der Schalie (Bulletin of the AMU 1980: 1 – 5).  I cannot discover when Miss Winslow actually assumed her position, but the date of her first “Occasional Paper” was 1917, a couple years after Walker’s first.

The Most Improbable Invasion?

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019d)  The most improbable invasion?  Pp 33 - 40 in The Freshwater Gastropods of North America Volume 4, essays on Ecology and Biogeography.  FWGNA Press, Charleston.

I've just returned from southeastern Pennsylvania, where I have seen, with my own eyes, the most improbable invasion in the history of malacology.  I think.  But before diving into the specifics, let’s review what we know about the biology of invasive species, shall we?

Invasive species are typically adapted to exploit rich, transient habitat patches.  They demonstrate “weedy” life history traits, for example high reproductive efforts (relative to body mass), short generation times, and semelparity.  And they also typically display special adaptations for dispersal, such as the production of propagules capable of long distance transport, and asexual reproduction.

All this has been a staple of the ecological literature at least since the days of Robert MacArthur’s “r and K selection” [1].  I myself developed a “USR” model of life history adaptation for my (2000) book, extending MacArthur’s two points to three, inspired by the triangular theory of J. P. Grime [2].  The most recent review of the biology of invasive species, from a malacological perspective, is that of Cowie and colleagues [3].

But no matter how you slice life histories, two ways or three, Pleurocera proxima must be the most unlikely invader in the entire North American freshwater gastropod fauna.  Populations of P. proxima are adapted to small, isolated, softwater streams of the southern Appalachians and upper Piedmont – harsh and poor in nutrients, but stable and predictable.  Females demonstrate very low reproductive efforts relative to their body mass, laying small numbers of small eggs annually, but are long-lived (perhaps ten years?) and iteroparous.

The dispersal capability of P. proxima is so poor that significant gene frequency differences have been documented over distances of only a few meters [4].  Populations simply do not move, and may not have moved for hundreds of millions of years [5]. When I first conceived of the USR model of life history evolution in freshwater mollusks, it was P. proxima I had in mind as the archetypical “S” species – a stress tolerator, the 180-degree opposite [6] of an “R.”  It’s a cactus, not a weed.

So I was shocked – as shocked as a snail guy can be – when I opened an email from Dr. Willy Eldridge of the Stroud Water Research Center in December of 2010.  The Stroud Lab is located in rural Avondale, PA, on a small tributary of the Delaware River called White Clay Creek.  And attached to Willy’s email was a photo of P. proxima.

I have dedicated much of my professional career to the study of P. proxima [7], logging thousands of miles on the back roads of the southern Appalachians to map its distribution.  And I knew, for an absolute fact, that the northernmost population of P. proxima reaches a tributary of the Roanoke River just south of Lynchburg, in central Virginia [8].  Here was a photo of my snail – the study organism for my dissertation, the coverboy of my book – snapped 400 km northeast of anywhere it could possibly be.

So it took me almost two years, but last month I sojourned to Pennsylvania to see this thing which has come to pass.  The population Willy showed me near the Stroud Lab [right] does not inhabit White Clay Creek itself, but rather a tiny tributary – a groundwater trickle – not a meter across.  And Willy reported that in the last couple years he has documented nine additional populations in similar little trickles, extending across 20 km of southeastern Pennsylvania through three tributaries of the Delaware – White Clay Creek, Red Clay Creek, and the Brandywine River.

My initial reaction was that it looked as though a 15 x 20 km rectangle of North Carolina had been transported three states north.  If anything, Willy’s ten Pennsylvania populations seemed even more isolated than typical P. proxima populations in the home range.  If this were North Carolina, I would have found a population in the (main) White Clay Creek, a couple hundred meters downstream from the trickle where the photo above was taken.  But I did not.

So Willy’s hypothesis is not that he has discovered an artificial introduction, but that he has discovered a natural extension of the range of P. proxima, however subsequently fragmented it may have become. Willy thinks that the absence of the snails from White Clay Creek (and 150 km of Maryland, and 250 km of Virginia?) may be due to road salt and other modern perturbations and disturbances.  Perhaps harsh agricultural practices over the last couple hundred years throughout the region? Or perhaps something bigger, over the last couple hundred million?  Hmmm.

I blame the DuPonts.  Nestled in the green, rolling hills approximately 10 km east of the Stroud Lab is Longwood Gardens, the estate of Pierre DuPont (1870-1954).  DuPont purchased the 1,077-acre property in 1906 [9] and over the course of thirty years developed a lavish horticultural complex of greenhouses, conservatories, gardens and farms, which he opened to the public on a regular basis.  And in his will he established the Longwood Foundation Inc, a charitable organization which continues to administer the grounds today as a public arboretum for “exhibition, instruction, education and enjoyment.”

Longwood Gardens is especially renowned for its fountains, pools, canals, and elaborately engineered water features.  As early as 1876, DuPont was “mesmerized by the huge display of water pumps in action at the Philadelphia Centennial Exposition,” and in 1893 he was “astounded” by the grandiose fountains at the Worlds Columbian Exposition in Chicago [10].  At Longwood he oversaw the construction of lavish “water gardens” which he seems to have stocked with a variety of aquatic vegetation from around the world.  I don’t actually understand the plumbing of the system, but I suspect that DuPont’s water works may bridge both the Brandywine River and Red Clay Creek.

Did Pierre DuPont import aquatic vegetation, rock, or other substrate from some stream in the southern Appalachians or upper Piedmont to stock his elaborate water gardens?  If so, how might P. proxima have spread from a Longwood focus, even if it does bridge the Brandywine and Red Clay systems, to the little tributary of White Clay Creek 10 km west where I snapped Willy’s photo last week, skipping (as it apparently has) a great many perfectly suitable little streams in between?  I do not know.

But I do know that the most important predictor of success in an invasive species is none of those I listed in the second paragraph of this essay.  Invasive species must be different.  Successful invaders exploit different resources, inhabit different habitat patches, and conduct their ecological business in a different fashion from native species.  And indeed all the successful invaders of the modern North American freshwater gastropod fauna - Pomacea, Bellamya, Viviparus, Bithynia, and Potamopyrgus – look strikingly different from any element of our native community, just as Corbicula and Dreissena look strikingly different from our native freshwater bivalves.  There are no cryptic invasions [11].

All of the life history adaptations I listed in paragraph two apply to species naturally adapted as invaders, which (as a general rule) they are always doing, naturally.  So focusing (as we are) on artificial introductions, the most important criterion for success becomes competitive ability – whether a potential invader is ecologically different enough to find an “empty niche” it can exploit upon its unexpected arrival [12].  And Pleurocera proxima is most certainly different from any other element of the freshwater gastropod fauna in southeastern Pennsylvania.  Or most of the world, actually.

Or perhaps Willy is right, and P. proxima is native to southeastern Pennsylvania?  And my paragraph two is complete as it stands, and the last five paragraphs I’ve written are wrong?  Willy tells me that he’s collecting genetic data that he expects will shed some light on this fascinating question.  We’ll keep you posted.

Notes

[1] MacArthur, R. H. (1962)  Some generalized theorems of natural selection.  PNAS (USA) 48: 1893-1897.  For a modern review, see Reznick, Bryant & Bashey (2002) r- and K-selection revisited: The role of population regulation in life-history evolution.  Ecology 83: 1509-1520.

[2] Dillon, R. T. (2000) The Ecology of Freshwater Molluscs.  Cambridge University Press.  See especially Chapter 4 (pp 131-136) and Chapter 8 (pp 354-364).  [Book site]

[3] Cowie, R. H., R. T. Dillon, D. G. Robinson & J. W. Smith (2009)  Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment.  Amer. Malac. Bull. 27: 113-132. [pdf]

[4] Dillon, R.T. (1988) The influence of minor human disturbance on biochemical variation in a population of freshwater snails. Biological Conservation 43: 137-144  [pdf]

[5] See “The Snails The Dinosaurs Saw” [16Mar09]

[6] Although Grime’s CSR model of life history evolution in plants was (quite literally) triangular, my USR model put U in the middle between S and R.  Hence there’s a full 180 degrees between S and R, not a mere 120.

[7] See my P. proxima page on the FWGNA site for the (N=16!) papers my colleagues and I have published on this fascinating species over the last 35 years.  [Pleurocera proxima]

[8] Setting aside the populations I myself introduced into a tributary of the Shenandoah in 1982.  See Dillon, R.T. (1986) Inheritance of isozyme phenotype at three loci in the freshwater snail, Goniobasis proxima: Mother-offspring analysis and an artificial introduction. Biochemical Genetics 24: 281-290.  [pdf]

[9] To be fair, the estate was originally developed as an arboretum by John and Samual Pierce as early as 1798.  By 1850 the Pierce brothers had “amassed one of the finest collections of trees in the nation” according to Wikipedia, and the property was already open to the public as “Pierces Park.”  So I suppose the introduction of exotic fauna (such as P. proxima) along with the flora might predate the DuPont era.

[10] I got most of this historical background from the (really quite lovely) Longwood Gardens website.

[11] Although invaders are never cryptic under native faunas, they are often cryptic among themselves.  So there are two more-or-less cryptic species of Asian Bellamya in North America, and two South American Pomacea, and two Eurasian Dreissena, and two east Asian Corbicula.  I think this tends to support my point, but I’m not sure how.

[12] This is the third time I have confessed an embarrassing predilection for the “empty niche hypothesis” on this blog.  Also see:

"Invaders Great and Small"  [19Sept08]

"Community Consequences of Bellamya Invasion"  [18Dec09]

When worlds collide: Lumpers and splitters

Apparently I have the reputation of being a “lumper.”  The subject came up last month when I was visiting my friend Tim Pearce, curator of mollusks at the Carnegie Museum in Pittsburgh.  Tim asked me a question, which was not actually in the form of a question, but rather phrased as a “philosophy of classification,” upon which he invited me to comment. Tim’s proposition was as follows: 

In the face of uncertainty, it is better to split than to lump.  Because if additional information subsequently becomes available suggesting that two taxa you have split should have been lumped, it will be trivially easy to lump them.  But if additional information becomes available suggesting that two taxa you have lumped should have been split, your entire data set may have been ruined, because information has been lost. 

My first response to Tim was that I’ve never been in such a position.  And my second response was that I could not imagine how such a situation could ever exist.

Is our ignorance complete and our uncertainty absolute, such that we have no existing taxonomy to guide us, no reference works of any sort to fall back on, nor any data to point us in one direction or the other?  And is somebody now holding a pistol to our heads, forcing us to make our decision?  We can’t simply leave the organisms unclassified?

The situation seems to be that we have been transported in shackles to Brazil, and made to classify beetles for our supper, without a guidebook.  I actually could not make my mind address Tim’s premise.

And then it occurred to me that Tim had phrased his proposition not as a question of science, but as a “philosophy of classification."  And it dawned on me that he and I were speaking different languages.

At dinner that evening Tim and I sorted the situation out.  As a museum curator, Tim spends most of his professional life with what we resolved to call a “Worldview of Information.”  He shares this worldview with print publishers, almost everybody involved in the (rapidly becoming omnipresent) internet, and anybody who may be left in the (rapidly becoming obsolescent) library.  Tim’s primary focus is not on the production of information, but on its management, organization, storage, and retrieval.

I spend most of my professional life with a Worldview of Science.  Science is the construction of testable models about the natural world.  The Worldview of Science is not incompatible with that of Information, of course.  When I publish a new hypothesis, or gather data supporting an existing hypothesis, I create information.  But Science is not compatible with an Information Worldview, either.  Because I focus on the quality of a model – old or new, good or bad – with no regard whatsoever for the organization, storage or retrieval of the information that will be generated as a byproduct.

The existence of parallel worldviews, each with its own language, culture, values and assumptions, has been a recurring theme on this blog for quite a few years now.  Most often I have contrasted the Worldview of Science with that of Politics and Public Policy – hit the “Science and Public Policy” tag at right for more [1].  I also posted one essay (back in February, 2011) contrasting Science with the Worldview of Art [2]. 

Religious faith is another obvious example of a parallel worldview.  I have a great deal of experience in the relationship between Science and Religion, although I have not published on this blog about the subject.  In other fora [3] I have compared that relationship to playing baseball and playing the banjo - neither more valid or more true, neither better nor worse, not incompatible, but not compatible, either.  Simply, profoundly different.

Subatomic particles are too small to see, but physicists can tell they are there when they run into each other.  The various Worldviews I have catalogued above – Art, Science, Politics, Religion and Information – are too big to see.  But one can tell they are there when they run into each other.

I have long derived embarrassing levels of schadenfreude from the Creation/Evolution controversy because I enjoy watching at least three [4] worlds collide - Science, Faith, and Politics.  Sitting in a meeting of the Senate Education Committee hearing testimony on creationist legislation we can watch baseball teams and bluegrass bands trying to drive nails with banjos and catcher's mitts, before a crew of carpenters.  I find this intellectually fascinating.

Science and Religion can collect Information into a three-world collision as well.  A google search on the keyword "evolution," for example, will return a steaming bouillabaisse of Science and Religion mingled in baffling fashion.  My good friend Kelly Smith from the Philosophy Department at Clemson has recently indicted the Information community for aiding and abetting Religion in its ongoing attacks on Science [5].

But the first commandment in Tim’s worldview is this: "Thou Shalt Not Lose Thy Information."  So seen in that light, his question about lumping and splitting put me in the position of a heathen, standing before the Spanish Inquisition.  Who could have expected that?

And my first commandment is this: "Thy Model Shalt be the Best."  As a scientist, I am horrified not simply by the quality of the information on “Wikipedia,” but indeed by the very concept of open publication itself [6].  I've spent a lot of time working with the NCBI GenBank in recent months, for example, and it turns out they will let any bonehead upload any string of the characters A, T, G, and C and call it anything.  The NCBI online resource may be dressed up like Science, but it is no more scientific than the B-Minor Mass.  And I don’t much care for Bach.

Ian Barbour

We'd all probably agree that worldview conflicts, whether they take the form of monkey trials, endangered species panels, or just prickly little interactions between museum curators and evolutionary biologists, are a bad thing.  But are they unavoidable?

My favorite treatment of worldview collision is that of the distinguished philosopher Ian Barbour [7].  Barbour's work specifically addresses the relationship between Science and Religion, but his ideas will generally apply to the relationship between Science and Public Policy, or Science and Information, for that matter.  In addition to conflict, Barbour has proposed three other forms of worldview interaction: independence, dialogue, and integration.

Independence is the model that Steven J. Gould famously called "Nonoverlapping Magisteria [8]."  And independence does indeed describe the actual relationship between baseball teams and bluegrass bands quite accurately.  Nobody has ever tried to bring a banjo into the batter's box, as far as I know.

All of the problems I have outlined above, however, arise from the intellectual appeal of integration.  Preachers do in fact propose science from their pulpits, and scientists do in fact propose public policy in their seminars, metaphorically carrying their banjos into batter’s boxes with the regularity of the tides.  In such situations, the only alternative to conflict is dialogue.

The first steps toward peace between two peoples are taken when those peoples begin to understand that they are, in fact, two peoples.  So I welcomed the dialogue Tim and I had in Pittsburgh last month, and do hope it will continue.  I am more than happy to let colleagues from the Worldview of Information handle all matters of data flow, storage, and retrieval.  We should be pleased if they would leave the Science to scientists.

Notes

[1]  Worldview collision is most explicitly addressed here:

Idaho Springsnail Panel Report [23Dec05]

When Pigs Fly in Idaho [30Jan06]

Red Flags, Water Resources, and Physa natricina [12Mar08]

Mobile Basin IV: Goniobasis WTFs [13Nov09]

[2]  When Art and Science Collide [4Feb11]

[3]  Only for those of you who can speak (or at least read) Religion!

• Dillon, R. T. (2008)  Stonewall, Woodrow, and Me: Reflections on the other great commission.  SciTech, The journal of the Presbyterian Association on Science, Technology, and the Christian Faith 17(3): 7 - 9. [pdf]
• Dillon, R. T. (2011) Charles Darwin and Theodicy.  (A celebrity death match between Rob Dillon and Francisco Ayala!)  SciTech, The journal of the Presbyterian Association on Science, Technology, and the Christian Faith 20(1): 1-3.  [pdf]
• Dillon, R. T. (2012)  Science and the Christian Religion: A Sermon in Three Acts.  Preached at Circular Congregational Church, Charleston, SC.  February 12, 2012. [pdf]

[4] I see three worlds colliding because I can understand their three languages.  I am fluent in both Science and Religion, and speak some Politics.  The Worldview of Education is also always represented in the constituency at hearings on creationist legislation, although silently.  On rare occasions somebody seems to attempt a pidgin form of Business and Commerce (“A rigorous science curriculum is necessary to advance South Carolina’s competitiveness.”)  But I don't speak any Money at all.

[5] Smith, Kelly C. (2012)  I Also Survived a Debate with a Creationist (with Reflections on the Perils of Democratic Information).  Reports of the National Center for Science Education 32(2): 6.  [pdf]

[6] The irony of publishing this statement in a blog post does not escape me.

[7] Barbour got his Ph.D. in Physics from Chicago in 1950, swapping over for a B.Div.