612 Commentary [Auk,Vol. 99

By studying and defining this variation, orni- lutionary units and thus would not be referable thologistsare able to add to the knowledgeof to the same subspecies.Graves (1980) re-ex- the earth's history. Obviously, not all variation amined the Colombianpopulation of Diglossa among closely related bird populations has (carbonaria) brunneiventrisand found that the progressedto the point at which those popu- population was separablefrom the Peruvian lations merit speciesstatus. To recognizethese birds. I feel that his action was correct in that populationsby naming them as subspeciesis the Colombian and Peruvian brown-bellied to acknowledgetheir existenceand to dem- birds, which are separatedby all-blackpopu- onstrate how the earth's history has affected lations, are separate evolutionary units and them. This idea is nowhere better illustrated should not be placedtogether under one name. than in the Andes, where geographicvariation To make the subspeciesconcept embrace an is obvious and populations are often isolated evolutionary unit would not affect its conve- from each other. I think that the subspecies nience, would make it more useful, and would concept is a valid one but that it should be get rid of the need to differentiatebetween the connectedto an evolutionary unit. If subspe- "evolutionary" and the "taxonomic" implica- cies are evolutionaryunits, then the usefulness tions that seem to be so often misused. I have of the conceptis greatly enhanced.If there is obviously oversimplifiedmany of the prob- no break in gene flow (i.e. a smooth cline), lems and have left out a great amount of in- then all populationsin that "aggregateof pop- formation that warrants discussion, but this is ulations" should be consideredto belong to necessarybecause of space constraints.I do, one form. When there is a break in the gene however, find the conceptto be very valuable flow by any type of separation (geographic, and very useful in the 1980's. ecological, etc.) then recognition of a second unit or subspecieswould be warranted. Vari- LITERATURE CITED ation within a cline can be discussed and de- GRAvEs,G. R. 1980. A new subspeciesof Diglossa scribed, but only a single name need be ap- (carbonaria) brunneiventris. Bull. Brit. Ornithol. plied. Two subspecies that seem to be Club 100: 230-232. morphologicallyalike but are separatedby a MAYR, E. 1963. Animal speciesand evolution. Cam- form that is different would be separate evo- bridge, Massachusetts,Harvard Univ. Press.

SUBSPECIES AND SPECIES: FUNDAMENTALS, NEEDS, AND OBSTACLES

ALLAN R. PHILLIPS 1

Populations are nature's building blocks. one or more of thesecomplexes does vary geo- When they do not differ consistentlyfrom oth- graphically,forming more-or-lesswell-defined er (usually more or less adjacent)populations, subspecies.There may alsobe areaswhere the the whole seriesforms a single subspecies•or variations are inconstant;such variable popu- species if essentially isolated reproductively. lationsshould not be arbitrarilysqueezed into Character complexes commonly varying, at one or anotherof the truly distinct subspecies. these levels, are measurements, details of Common patternsof racial or subspecificvari- colors, or more rarely facial patterns or colors ation are clinal or convergent,open-ring, bro- of soft parts. In most widespread species(es- ken-ring or divergent, parallel, and nonclinal pecially if not stronglymigratory or nomadic), or random (which should normally not be named) (Phillips 1959). Treatmentof speciesand subspecieshas var- Apartado Postal 370, San Nicolas de los Garza, ied widely. Most Europeansbefore Hartert re- Nuevo Le6n, M•xico 66400. jected the subspeciesconcept, calling every July1982] Commentary 613 recognizableform a species.Hellmayr, at the though this may be hard to measure.We must other extreme, considerednearly every allo- not be blind slaves to statistics. patric form a subspecies,paving the way for Note that the membersof the populations Mayr and Amadon (1951)to reducethe world's must differ; entire populations are not com- Recent avifauna to 8,519 species.Mayr's fol- pared. White and dark geeseare color phases lowers have most recently(Bock and Farrand or "morphs"; while eachoccupies certain parts 1980) conceded that at least 9,021 speciesexist, of the breeding range exclusively, in other a figure surelywell shortof reality. [I still con- parts they mix, and no one recognizesSnow sider my guess(Phillips 1959)of about 10,000 and Blue geeseas subspecies.Selander's pro- speciesa reasonable one.] But instead of these posal (1959)to recognizeraces based on occur- guesses,we urgentlyneed field studiesand ex- rence of "morphs" is unacceptable;what hap- plorations.Mayr, Bock,and Farrandare quite pens when unexpected individuals turn up in wrong in stating that "the biological species other populations, and how do we identify concept . . . becomesless and less applicable single specimens?True subspeciesare more to populationsreplacing one another over in- substantial. creasing geographicaldistances." Biology is Subspeciesare no new discovery;they have not dependent on distance,and only slightly been known longer than sibling species, on ecology. Mayr and his followers would do though at first termed species or varieties. well to familiarize themselves with avian bi- Thus, 3 subspeciesof Motacilla fiava (Yellow ology:nests, eggs, flesh colors,behavior (in- Wagtail) from northern Eurasia had been cludingvocalizations), and skeletalstructures. named by 1789and 6 palearcticraces of M. alba Their belief that all forms of Morus, Anhinga, (White or Pied Wagtail) were described by Haematopus,etc. are allopatric does not prove 1838, whereas before 1811 only 1 species (2 that these forms are subspecies(cf. Brodkorb subspecies)of the various EurasianPhyllosco- 1963, Morus; Phillips et al. 1973, Phillips MS, pus warblers had been described,and only 1 Polioptila;Baker 1974,Haematopus). Simple vi- of the 5 speciesof easternNorth American Em- carlance of surviving taxa does not determine pidonaxflycatchers. Only the most distinctive their taxonomic levels. As Coues long ago of the other, western United States Empido- wrote, species are better determined in the naceswas recognizablydescribed before 1856; field than in the closet!An excellentexample indeed the status and nomenclature of these of the sort of field approachthat is neededis speciesin North Americawas not finally set- provided by Lanyon's(1978) vocalization play- tled until 1973!Other sibling species,like sub- back studiesof Myiarchusflycatchers. Such in- species, continue to turn up. vestigationsare urgentlyneeded of many more In the past 30 yr, severalwriters have sought genera, especiallyin the tropics. to convincethe unknowing that subspeciesare Subspecies are morphologically or geo- a fictional concept, unstable in time, and that graphically significant populations whose their recognitionis at best dubious. Uniform- members differ morphologically, at some ly, they studiouslyignore the many truly dra- stage, from those of other populations(of the matically different subspecies, such as the species)to a conventionaldegree; commonly, above Motacillae, Canada Geese, flickers, vari- we insist that at least 75% of the birds must be ous juncos, and other sparrows,etc. Johnston distinguishablefrom 99% of those of other and Selander's"House Sparrows: rapid evo- populations. This convention has been mis- lution of races in North America" (1964) may interpreted to mean they must differ in some be instructive.They claimedthat recentfall se- one character to that extent. Often, however, ries from 20 points in North America (plus more than one character is involved, and at Hawaii and Bermuda) showed that each pop- least 75% of the birds must be separablefrom ulation "has differentiatedto greateror lesser other populationsin one or another character. degreefrom any otherand from the Old World Single-characterraces are, in fact, unusualand stock,"and that this was geneticallycontrolled often rather weak. If a bird is darker, this will (including a "conspicuous yellow wash" at usually affect various parts of the plumage; if Oaxaca, Oax., M•xico, where in fact Passerar- an insularbird's bill is larger,it will usuallybe rived not long before 1962). They correlated both longer and deeper (or perhaps wider), colorvariation with temperatureand humidity 614 Commentary [Auk,Vol. 99 but ignored soot, smog, or other discoloration leaving less room for doubts and disagree- in urban populations, plus the basic fact that ments. the birds were not washed before skinning. The utility of subspecieswould undoubtedly They concluded:(a) "levels of differentiation be enhanced if all competent taxonomists ... are fully equivalent to those shown by agreed on all details. This utopian ideal is un- many polytypic native species .... applica- attainable, if for no other reason than differ- tion of subspecifictrinomials to certain New encesin ocular acuity, combinedwith the dif- World populations .... would be fully war- ficulty of verbally expressing differences ranted . . ."; and (b) much of the "differentia- visible to the eye. Nevertheless,much could tion" must have occurred in the present cen- be done to improve the presentunsatisfactory tury; this they found concordantwith changes situation. within historic time in other groups, citing For one thing, I am constantlyimpressed by amongother authorsWilson and Brown (1953). the minute taxonomicvalue of the average In cold fact, the differentiation in color had museum's skins. Most are badly worn, and probably occurredsince the precedingAugust, often dirty, and would have been better pre- having nothing to do with genetics.Interest- served for anatomical studies than as skins. ingly, when someonemisled by this did map Add to this that, in most parts of the world, a few of these supposedsubspecies, Johnston the vastmajority of bird populationshas never and Selanderreplied (1966):"We did not . . . evenbeen sampled,but only thoseof easyac- describe'subspecies' of house sparrows.... cess or promising habitats. Yet we are con- Designating and mapping the ranges of five stantly told that the day of the collectorhas 'subspecies'of house sparrowsin North Amer- passed!Not only are the points from which we ica... clearlydemonstrates several objection- have specimenswidely scattered on even a able features of the subspeciesconcept and small-scalemap, and the specimensin poor strengthensthe argument for abandoning it condition and poorly dissectedand annotated, altogether." but collectionsare usually badly skewed to- What Johnston and Selander did in fact dem- ward adult males at the expenseof femalesand onstratewas selectionfor larger size in areas young of different ages. Yet, in dimorphic with cold winters. But only specimensdem- species,it is often the adult male that is least onstrating the full range of variation of the usefultaxonomically. For example,in Carduelis original stocks,introduced from variouspoints, psaltria(Lesser Goldfinch), studiesover several could show that variation has increased. Be- yearshave shownme that currentlyrecognized causeevolution implies changefrom ancestral taxonomy, based on the available adult male stocks,not mere reshufflingof averages,John- plumage, is quite inadequate; yet besides ston and Selander's title is patently untrue. Yet being scarce,material of females and young it has had an unfortunate effect on the beliefs must be divided into five age/sexclasses before of others. reliable comparisonscan be made. Yet gold- Many subspecieshave, to be sure, beenmis- finches are easily collected. Those who com- understood. To err is human, especiallywith plain about the instability of subspecificcon- poor material. Probably no one's record on cepts or nomenclatureshould get busy in the subspeciesis perfect, and my own could be field. It is inexcusable that useful material of much better. But specieshave alsobeen abused even common birds remains unavailable from and misunderstood (cf. "Psaltriparusmelano- vast extents of accessibleterritory. (Nor will tis," "Pipilo ocai," Junco"caniceps," etc.); so single specimens assure correct results; we have genera [cf. Oberholser(1974), particularly should have series.) on "Phasmornis"and "Oreothlypisvirginiae"]. A casein point in the easternUnited States Should we then abandon these "concepts" al- is the Brown Creeper (Certhia "familiaris"= together?If we ceaserecognizing subspecies, americana).A supposedAppalachian race, ni- we must re-elevate all notable ones, at least, to grescens,was named years ago from breeding species rank, thus destroying the biological birds of little if any taxonomicvalue. As yet, speciesand plunging our classificationback so far as I know, all major collectionstogether toward the early 19th century. This would have exactlyone useful specimenamong them surely be a great step backward. Rather, we to judge the characters,validity, and winter must refine subspecieswith far better material, range of the race. Every year the period from July1982] Commentary 615 mid-August(when birds are cominginto fresh need of surveys. Meanwhile, our scientific basicplumage) to mid-September(when fully "establishment" unanimously ignores most molted migrantsstart arriving from the north) subspeciesand concentrateson supporting in- passes with no one collecting Appalachian dustry (profitably) by emphasizingcomputers creepers,Winter Wrens, etc. What right, then, and expensive equipment designed to give have the idle to criticize?When adequatema- fantasticUltimate Answers (based on proteins terial becomes available, taxonomists will be and molecules)that, to date, have been largely only too happy to study it. Meanwhile, of wrong.Truly, we arein a new Declineand Fall, course, all reports of nigrescensmigrating or with our scientific establishment fiddling wintering here or there necessarilyrepresent while Rome bums, instead of conservingbio- more-or-less educated guesses, based, one logicaldiversity. suspects,on foxing (post-mortemchanges in museum skins) and soot-discoloration. There is reason for dissatisfaction. LITERATURE CITED Finally, scientific specimensshould be the BAKER,A. J. 1974. Prey-specificfeeding methods of property of science,available for study by spe- New Zealand oystercatchers.Notornis 21: 219- cialistsat any time. But this is not the casewith 233. some small colleges,and even the important BocK, W. J., • J. FARRAND,JR. 1980. The number of Moore Laboratory of Zoology refuses to loan speciesand genera of Recent birds: a contribu- specimensfor months at a time, a corollaryof tion to comparative systematics. Amer. Mus. the situation about which Olson so rightly Novitates 2703: 1-29. complains (1981). BRODKORB,P. 1963. Catalogueof fossil birds, part Subspecies, despite all misleading attacks, I (Archaeopterygiformesthrough Ardeiformes). Bull. Florida State Mus., Biol. Sci. 7: 179-293. remain basicunits in ornithology.As Marshall states (1964), they constitute whole popula- JOHNSTON,R. F., & R. K. SELANDER.1964. House Sparrows: rapid evolution of races in North tions marked by certainpeculiarities, enabling America. Science 144: 548-550. us to trace them on migration and in winter. , & . 1966. On supposed "subspecies" They are thus the basisof much of our knowl- of North American House Sparrows.Syst. Zool. edge of migrations. 15: 357-358. The differencebetween speciesand subspe- LANYON,W. E. 1978. Revision of the Myiarchusfly- cies is biological,requiring field studiesof a catchers of South America. Bull. Amer. Mus. vast number of kinds of birds in rapidly van- Nat. Hist. 161: 427628. ishing habitats. We shall never know how MARSHALL,J. 1964. Introduction. Pp. ix-xi in The many full speciesof birds inhabited the planet birds of Arizona (A. Phillips,J. Marshall, and G. Monson). Tucson, Arizona, Univ. Arizona when we began its destruction,or even when Press. we recently acceleratedthis destruction.It is MAYR, E., & D. AMADON. 1951. A classification of past time to get afield and away from minutiae Recent birds. Amer. Mus. Novitates 1496: 1-42. and speculations, back to solid facts of bird OB•RHOrSER, H. C. 1974. The bird life of Texas. distribution, variation, and migration. Suc- Austin, Texas, Univ. Texas Press. cessfulconservation will require intelligence, OrsoN, S. L. 1981. Commentary.The museum tra- realism, and knowledge,based on better col- dition in ornithology--a response to Ricklefs. lecting of what there is to conserve.It cannot Auk 98: 193-195. be basedon lying politics,fanaticism, or some PHitries, A. R. 1959. The nature of avian species. inapplicableethic. It should include, in emer- J. Arizona Acad. Sci. 1: 23-30. gencies,captive breeding, with due respectfor --, S. SPEICH, •: W. HARRISON. 1973. Black- capped Gnatcatcher,a new breeding bird for the the integrity of stocks--againimplying sub- United States;with a key to the North American species.It can hardly be achievedwhile "con- speciesof Polioptila.Auk 90: 257-262. servationists"and misled officials impede the SELANDER,R. K. 1959. Polymorphismin Mexican collecting,preservation, and study of our fast- Brown Jays. Auk 76: 385--417. vanishing wealth. This is concentratedin the WILSON, E. O., & W. L. BROWN,JR. 1953. The sub- tropics,the very areasmost under assaultfor species concept and its taxonomic application. blind, short-term "development"and most in Syst. Zool. 2: 97-111.