TheAuk 115(1):127-141, 1998

MOLECULAR AND OSTEOLOGICAL PHYLOGENIES: SOURCES OF INCONGRUENCE

KEVIN G. MCCRACKEN •'3 AND FREDERICK H. SHELDON 2 •Schoolof Forestry,Wildlife, and Fisheries and 2Museum of NaturalScience, Louisiana State University, BatonRouge, Louisiana 70803, USA

ABSTRACT.--Payneand Risley's(1976) comparison of 33 osteologicalcharacters of was the first cladisticestimate of heronphylogeny. Among their findingswere two major clades:(1) Boat-billedHeron (Cochlearius cochlearius), night-herons, and bitterns; and (2) ti- ger-heronsand day-herons. In contrast,more recent DNA-DNA hybridization comparisons, cladisticanalyses of vocalizations,and mtDNA sequencedata portray a more asymmetric phylogeny,with day-heronsand night-heronsforming a cladewith bitternsas their sister group,and tiger-herons and the Boat-billedHeron branching basally. To explorethe source of the disagreementbetween these phylogenetic estimates, we reanalyzedthe osteological datausing modern cladistic methods and comparedthe resultswith the DNA-DNA hybrid- izationtree usingtaxonomic congruence analysis. Character-by-character comparisons be- tweentrees and among lineages within treessuggest that similar cranial morphology in the relativelyunrelated tiger-herons and day-herons has resulted in themisleading attraction of thesetwo lineages in osteologicalestimates of phylogeny.Apparent convergence in bill mor- phologyand modifications of orbitalstructures for nocturnalfeeding in night-heronsand Boat-billedherons have led to furtherdisagreement between data sets. In part,problems in the osteologicaldata stemfrom the relativelysmall character matrix of Payneand Risley (1976),but ultimatelythey may derive from usinghighly adaptive characters to reconstruct phylogeny.In this case,the cranialcharacters are functionallycorrelated as part of the pi- scivorousheron Bauplan. As such,they relateto the forcesresponsible for speciationand divergencein theearly history of thegroup but may not be useful for phylogenetic inference. Thediscovery of biasin cranialcharacters underscores the valueof taxonomiccongruence analysisand the needto explorecases of phylogeneticincongruence. Received 19 June 1996, accepted24 June1997.

CONGRUENCEANALYSIS of independentesti- pursuit.Nonetheless, when phylogenies are in- mates of phylogenyis a useful method for congruent,phylogeneticists tend not to pursue judgingphylogenetic accuracy (Mickevich and the matter. When available, molecular data sets Johnson1976). Agreement in branchingpat- oftenare preferred because they are considered terns in treesfrom different data setsprovides more objectivethan morphologicalor other strong evidenceof phylogeny(Bledsoe and data in which charactersare judged prior to Raikow 1990, Swofford 1991, Miyamoto and tree-building(Sibley and Ahlquist 1987).Not Fitch1995). When phylogenies disagree, how- only doessuch an approachfail to recognize ever, interestinglessons about evolutionand the many problemsof moleculardata, it ig- the mechanicsof phylogeneticestimation also norespotentially useful information in the re- may be learned.Incongruence can result from jecteddata set. Advocates of charactercongru- biaseddata derivedfrom poor samplingstrat- ence (e.g. Kluge 1989, Kluge and Wolfe 1993) egies(e.g. using correlated characters) or idio- avoid this problemby combiningdata into a syncrasiesof evolution(e.g. differences in rates single tree-buildingeffort accordingto the of characterchange or characterconvergence) principle of total evidence.But, in certain in- in oneor both datasets (Wiley 1981, Patterson stances,it is not possibleor desirableto com- et al. 1993).Because the discoveryand expli- bine data sets,e.g. if oneset consists of obligate cation of characters that have evolved in unusu- distances,like thoseof DNA-DNA hybridiza- al waysare main goalsof evolutionarybiology, tion (Sheldonand Whittingham 1997), or if one the analysisof incongruenceis an interesting is suspectedof containingnon-phylogenetic in- formation (Bull et al. 1993, de Queiroz 1993, Miyamotoand Fitch1995, Page 1996). In such 3 E-mail: [email protected] cases,taxonomic congruence (Mickevich 1978),

127 128 MCCRACKENAND SHELDON [Auk,Vol. 115 which maintainsindependent data sets,is the are largely congruent(Figs. 1A, B), depicting: appropriatemethod of analysis. (1) day-heronsand night-heronsas the sister Among groups,the herons(Ardeidae) taxonof bitterns,and (2) the Boat-billedHeron offer a particularly promisingopportunity to (Cochleariuscochlearius) and tiger-herons as study sourcesof phylogeneticincongruence. branchingbasally. This configurationis iden- Therehave been three rigorous studies of heron tical to that suggestedby preliminarycladistic phylogenyusing three differentkinds of data analysisof mitochondrialnucleotide sequences and two types of analysis:(1) a cladisticanal- (1,065bp) of the cytochrome-bgene for the ysisof osteologicalcharacters (Payne and Ris- sametaxa (K. McCracken,C. Jones,and E Shel- ley 1976),(2) DNA-DNA hybridizationdistance don unpubl. data).However, this configuration comparisons(Sheldon 1987a, b; Sheldonand is incongruentwith major portionsof the os- Kinnarney1993; Sheldon et al. 1995),and (3) a teologicaltree (Fig. 2), which consistsof two cladistic analysis of vocal characters (Mc- main cladesof herons:(1) Boat-billedHeron, Crackenand Sheldon1997). The analysesbased night-herons,and bitterns; and (2) tiger-herons on DNA-DNA hybridizationand vocalizations and day-herons.This incongruencemust stem

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-- Egrettathula 0.8kHz__ Ardeaherodias • • 0.7kHz Ardeaalba !• 0.5kHz

-- Bubulcus 0.6kHz

Butorides striatus o.$kHz Nyctanassaviolacea • i 0.7kHz Nycticoraxnycticorax o.sskHz

Zebrilus undulatus -•-- o.5kHz

__ BotaurusIxobtychuslentiginosusexilis [,••!•., ,, 0.50.35kHzkH• __ CochleariuscochleatJus •[J• J l J • • o.2skH?

Tigrisomalineatum ...... o.3o

--' Tigtiomisleucolophus

Seconds

F[c.1. DNA-DNAhybridization and vocal estimates of heronphylogeny. (A) Branchtopology represents the bestestimate of heronphylogeny based on DNA-DNA hybridization(Sheldon 1987 a, b; Sheldonet al. 1995).(B) Strictconsensus of two trees(length = 7, CI = 1.0,RI = 1.00)estimated with PAUPusing three informativevocal characters that trackheron phylogeny (McCracken and Sheldon1997). Vocal characters include,fundamental frequency (kHz), syllabicstructure (tonal/harmonic), and numberof syllables.Fun- damentalfrequency was orderedbecause it is continuous.Syllabic structure and numberof syllablesare discreteand were codedas unordered.A randomizationtest for phylogeneticconservativeness (Maddison and Slatkin1991) suggested that the arrangementof charactersinto sharedancestral and derivedstates cor- respondsstrongly with the hierarchicalarrangement of brancheson the DNA-DNAhybridization tree (P < 0.0001).Vocal recordings not availablefor Tigriornisleucolophus. January1998] HeronPhylogeny 129

Sy#gmasibilatdx PIIherodiaspileatus Egrettarufescens Egrettapicata Egrettatricolor Egrettaintermedia Bubulcus ibis Egrettanovaehollandiae 63 Egrettacaerulea Egrettathula Egrettagarzetta Egrettasacra Egrettaardesiaca 6o Ardeola ralloides Ardeola grayii Ardeola bacchus Aredola rufiventds Butoddes stdatus Agarniaagarni cinerea Ardea herodias Ardea cocoi Ardeapacifica Ardea melanocephala 100 53 Ardea surnatrana 781 Ardea goliath Ardea pupurea Ardea alba Tigdsomamexicanurn 100 Tlgdsomalineatum Tigdomisleucolophus Nyctanassviolacea Gorsachiusmelanolophus Zebdlus unduiatus Ixobtychusinvolucds 95 Ixobtychusexilis Ixobrychusminutus Ixobrychussinensis Ixobrychuseurythrnus Ixobrychuscinnarnomeus • Ixobq/chussturmii Ixobrychusfiavicollls Botauruslent•ginosus 51 Botauruspinnatus Botaurus stellads Botauruspoiciloptilus Gorsachius leuconotus Nycticoraxnycticorax Nycticoraxcaledonicus Cochleadus cochleadus Prirnardea

FIG. 2. Osteologicalestimate of heron phylogenyusing 30 skeletalcharacters and "primardea"as the outgroup.Fifty-percent majority-rule consensus (Rohlf's CI[1] = 0.717)of 4,100most- parsimonious trees (length = 143,CI = 0.336,RI = 0.790). from evolutionaryphenomena, a mistake in three very different data sets (i.e. DNA-DNA characterselection, problems with analysis,or hybridization, vocalizations,and mtDNA se- some combination of these factors. quences)yield highly congruenttrees suggests The first task is to determine whether DNA- that these analysesyield the best estimateof DNA hybridization/ vocalizations / cytochrome phylogeny.Using this logic, we demonstrate b or the osteologicalanalysis provides the most that disagreementbetween DNA-DNA hybrid- accurateestimate of phylogeny.In the absence ization,vocalizations, and cytochromeb versus of this information,either phylogenetichy- Payneand Risley's(1976) estimate of phyloge- pothesismight be takento be correct,whereby ny basedon osteologicalcharacters largely re- datafrom the othercould be fitted accordingly suits from the influence of cranial characters in to observe patterns. However, the fact that the osteologicaldata. Under the rubric of cla- 130 MCCRACKEN AND SHELDON [Auk, Vol. 115

TABLE1. Correctionsto Payneand Risley's(1976) matrix of skeletalcharacters.

Species Character,state Pilherodiuspileatus Character 3, state 1 Egrettanovaehollandiae Character 3, state 1 Egrettacaerulea Character 9, state 0 Nyctanassaviolacea, Nycticorax nycticorax, N. ca- Character 22, state 2 ledonicus,Gorsachius melanolophus Gorsachiusleuconotus (UMMZ 201761) Previouslyundescribed states same as G. melanolophusex- ceptforcharacters6(2), 21(1),and 30(0) Zebrilusundulatus (LSUMNS 136695) Previouslyundescribedcharacter states for characters 3(1), 4(1), 13(1), 23(1), 24(1), 25(1), and 26(0) Ixobrychusminutus Character 3, state 1 distics,the problemcan be attributedto cor- currentevidence indicates that they are not herons relatedsymplesiomorphic characters in tiger- and may not be a closeoutgroup (see Sibley and heronsand day-herons,and convergenceand Ahlquist1990, Feduccia 1996). Thus, we excludedthe LesserFlamingo from all further comparisons. specializationin night-herons,Boat-billed Her- Character states were coded and ordered accord- ons, and to a lesser extent in bitterns. We also ing to Payneand Risley(1976). Because only 33 skel- comparerates of molecularand morphological etal characterswere usedto compare49 heronspe- change,but find no evidencethat high ratesof cies,we facedtwo problemsin our reanalysis.First, skeletal-characterevolution are relatedto high the large number of speciesprecluded use of ex- ratesof single-copyDNA evolution. haustiveand branch-and-boundsearch algorithms, whichyield the most-parsimonioustree, and instead METHODS required the use of a heuristic-searchalgorithm. Heuristic-searchalgorithms do not necessarilyfind Reanalyzingthe osteologicaldata.--We reanalyzed the most-parsimonious tree but, in somecases, may Payneand Risley's(1976) skeletalcharacter matrix convergeon a localparsimony minimum rather than using PAUP 3.1.1 (Swofford 1993), a parsimony- the globalminimum. Second, the probabilityof dis- based software packagethat was not availableto covering a single most-parsimonioustree is small Payneand Risley(1976). Corrections to the original with lessthan two or three charactersper taxon.Ac- matrix includedstate changes for eight taxa (R. B. cordingly,we employeda meticuloussearch strategy Paynepers. comm.)and the inclusionof new char- to circumventthe problems of toomany taxa and too acterstates for the White-backedNight-Heron (Gor- few characters. We used the tree bisection-reconnec- sachiusleuconotus; R. B. Paynepers. comm.)and the tion branch-swappingprocedure to increase the Zigzag Heron (Zebrilusundulatus; coded by us;Table probabilitythat the heuristicsearch would find the 1). Unfortunately,skeletons of Ardeaimperialis, Egret- most-parsimonioustree, and repeated the search100 ta eulophotes,and Zonerodiusheliosylus were unavail- times. We initiated each search with a random ad- ablefor analysis.Appendix 1 containsa completelist dition sequenceto ensureunbiased sampling of tree of taxaincluded in our analyses. space.One hundred trees were saved at each step, Payneand Risley(1976) used a hypotheticalheron potentiallyyielding a maximumof 10,000trees per ancestor,"primardea," asan outgroupin their anal- analysis. yses.They derivedcharacter states for primardea Tracingcharacter evolution and testingcongruence.- from 10 non-heron ciconiiforms using phenetic We optimized Payne and Risley's (1976) skeletal methods. We repeated Payne and Risley's (1976) charactersonto the DNA-DNA hybridizationphylog- analysisusing primardea. However,because using eny (Fig. 1A) and the skeletaltree using PAUP to real taxa as outgroupsrequires no ad hocassump- studyskeletal character patterns. We usedboth ac- tions about primitive characterstates (Nixon and celeratedtransformation (ACCTRAN) and delayed Carpenter1993), we also used the samenon-heron transformation (DELTRAN). ACCTRAN and DEL- ciconiiformsfrom which Payne and Risley (1976) de- TRAN analyseswere consistent,so we report only rived primardeaas an outgroup.Another substantial the ACCTRAN optimizations.We recorded each differencein our reanalysisconcerned the Lesser statechange for eachcharacter on both the DNA tree Flamingo (Phoeniconaiasminor). Payne and Risley and the skeletaltree (Appendix2). Paralleland re- (1976:37)noted a problem with this speciesas an versestate changes were determinedfor eachchar- outgroup,and we found that it appearedas an in- acter by the characterstate at the outgroupnode. groupmember in our initial analysis.The relation- Multifurcationswere considereduncertain and op- shipsof flamingosremain poorly understood,but timized mostparsimoniously to avoidinflating the January1998] HeronPhylogeny 131 numberof characterchanges in unresolvedparts of billed Heron DNA. We calculatedthe numberof par- the trees. allel and reversestate-change events for eachchar- To testnull hypothesesof no differencein number acterin the DNA tree in eachof theseheron lineages of characterchanges between the molecularand (Appendix3). State-changepolarity was determined morphologicalbranch topologies, we performeda by thecharacter state at the outgroupnode. Next, we seriesof nonparametricwinning-sites tests (Prager useda contingencyanalysis (PROC FREQ SAS 1990) and Wilson 1988; see also Templeton 1983). Para- to testthe null hypothesisthat frequencies of cranial metric Kishino-Hasegawa(1989) winning-sites tests and postcranialparallel and reverseevents do not generallyare applied to sequencedata. However, differ amongbitterns, day-herons and night-herons nonparametrictests offer a more appropriate test andbetween tiger-herons and the Boat-billed Heron. statisticfor data sets such as Payne and Risley's (1976), which contain small numbersof characters RESULTS that are not normallydistributed. Moreover, parallel and reversesteps can be scoredseparately to parti- tion the effectsof theseprocesses on tree topology. ReanalysisofPayne and Risley• data.-•Our tree The testingprocess was as follows.We scoredthe including49 heronspecies, 30 informativeskel- differencein numberof stepsfor eachvariable char- etal characters,and the compositeoutgroup acter between the morphologicaland molecular primardea(Fig. 2) is nearly identicalto Payne trees,identifying parallel and reversestep events in and Risley's(1976) Wagner tree. This tree dis- eachinstance. We thencompared the distributionof tinguishestwo mainclades: night-herons and scores for each variable character with the binomial bitterns,and tiger-herons and day-herons. distributionto test hypothesesof overalltree simi- When we included 10 non-heron ciconiiform larity. Like otherstatistical tests, winning-sites tests speciesas the outgroup,the LesserFlamingo rely upon the assumptionthat eachcharacter is in- dependent.To the extentthat one or more skeletal emergedas sister to thetiger-herons within the charactersare not independent,the effective number day-herons.This arrangementwas supported of degreesof freedommay be overestimated.We in- unambiguouslyby 26 skeletalcharacters and vestigateddifferent tree topologiesand calculated strict consensus(Rohlf's CI[1] = 0.503).Delet- stepdifferences for alternativeconstructions of con- ing theLesser Flamingo from the analysis had tentious nodes. no substantialeffect on the overallbranching Next, we used a priori criteria to group skeletal patternin Figure3. However,Figures 2 and 3 characters.Payne and Risley(1976) included 33 skel- differsubstantially in thepositions of theBoat- etalcharacters in theiranalyses (one of thebill, three billedHeron, night-herons, day-herons, and ti- palatal,two orbital,three lacrimal, three ectethmo- idal, one of the foramenmagnum, three vertebral, ger-herons,indicating the stronginfluence of three sternal, one coracoidal,two furcular, four hu- real outgroupsversus a hypotheticaloutgroup. meral, five synsacral,and two tarsometatarsal).We In Figure3, Cochleariusdoes not form a mono- appliedwinning-sites tests to eachof thesegroups phyleticgroup with night-heronsand bitterns, to determine whether parallelisms,reversals, and but rather is the sister taxon of all other herons. consistencyindices differed between molecular and Night-heronsdo not form a monophyletic morphologicalestimates of phylogeny.Character groupwith the bitterns.Instead, the bitterns groupsthat did not differ significantlybetween trees are thesister taxon of the day-heronsand tiger- (P < 0.05)were pooledwith the nearestanatomical herons.The outgrouptopology is concordant group(s).Groups that differedsignificantly were re- tained. Using this procedure:(1) pelvic, vertebral, with Sibleyand Ahlquist(1990). andpectoral characters were combined to forma sin- Molecular and morphologicalcongruence.- gle group consistingof all postcranialcharacters; Comparisonsof the DNA-DNA hybridization and (2) bill, palatal, orbital,lacrimal, ectethmoid, estimateof heronphylogeny (Fig. 1A) and the and foramenmagnum characters were combinedto skeletaltrees (Fig. 3) agreein that the Boat- form a groupconsisting of all cranialcharacters. billed Heron is basal to all other herons, and the Followingthese results, we testedwhether cranial bitternsare the sistertaxon of the day-herons. and postcranialfrequencies of characterevolution However, the DNA-DNA hybridizationand differedamong heron lineages using the DNA-DNA skeletaltrees do not agreeas to thepositions of hybridizationtree (Fig. 1A). Sheldon(1987b) discov- ered differencesin ratesof single-copyDNA evolu- tiger-heronsand night-herons. tion amongthe three main heron clades; bittern DNA We enteredthe DNA-DNA hybridizationtree evolved-25% fasterthan day-heron and night-her- and a reduced skeletal tree of the same taxa and on DNA, which in turn evolved -19% faster than Ru- a topology consistentwith Figure 3 into fescentTiger-Heron (Tigrisoma lineatum) and Boat- MacClade(Maddison and Maddison1992) and 132 MCCRACKENANDSHELDON [Auk,Vol. 115

Sydgrnasibllat#x Pilherodiaspileatus Ardoa c/nerea Ardea herodias Ardea cocoi Ardeapacifica Ardeamelanocephala Ardea surnatrana Ardea goliath Ardeapupurea Ardea alba 10o I.•arniaagarnl _•igrlsornamexicanurn •œgrlsorna#neaturn ioo 77g#ornisleucolophus E_grettapicata E_•retta tricolor E_•retta novaehollandiae E• rettacaerulea • rettathula • • retta ga•zattasacre 10o Egrettaintermedia Bubulcus ibis loo Egrettaardesiaca Ardeola ralloldes Ardeolagreyii Ardeola bacchus Ardeola rufivent#s Butorldes stdatus Egrettarufescens 57 Zebrilus undulatus IxobG,chusfiavicollis 10o IxobG,chusinvolucrls IxobG,chusexllls IxobG,chusminutus 10o IxobG'chusslnensis I.xo.bG,c.hus euorthrnus Ixoorycnuscinhemorneus 76 Ixobrychussturmii Botauruspinnetus Botaurus stellads Botauruspoiciloptilus Botauruslentiginosus Gorsachiusmelanolophus Gorsachius lauconotus Nyctanessaviolacea 10o Nycticoraxnycticorax Nycticoraxcaledonicus Cochlea#us cochlea#us 96 89 alba Anastomus oscitans Hagedashiahagedash P.l.•adischlhi Al•ia ajaja Scopus urnbretta Leptopffioscrurneniferus Balaenicepsrex

Fid. 3. Osteologicalestimate of heronphylogeny using 33 skeletalcharacters and 9 non-heron ciconi- iformsas the outgroup. Fifty-percent majority-rule consensus (Rohlf's CI[1] = 0.684) of 2,500 most-parsi- monioustrees (length = 179,CI = 0.285,RI = 0.782).

PAUPto examinecongruence between Figures wereoptimized over the skeletal tree (Fig. 4). If I and 3 (Figs.4 and 5). DNA-DNAhybridiza- the DNA tree is correct,the skeletalcharacters tionestimates used the Glossy Ibis (Plegadisfal- possess substantial homoplasy; parallel and re- cinellus)as the outgroup.To controlfor the ef- verseevents occur more frequently in theDNA- fectsof differentoutgroups, we attachedour DNA hybridizationtree than in the skeletal non-heronciconiiform outgroup tree to thein- tree.Repositioning the tiger-heronsplus Boat- group of the DNA-DNA hybridizationtree billed Heron as sister taxa to the rest of the her- usingMacClade (Fig. 5). When the morpholog- onsrequires seven additional steps (length = ical characterswere optimized over the DNA- 144,CI = 0.333,RI = 0.622).Further placing the DNAhybridization tree (Fig. 5), 26more steps bitternsas the sistergroup to the day-herons were requiredthan when the samecharacters andnight-herons requires an additionalseven January1998] HeronPhylogeny 133

4

F•. 4. Osteologicalestimate of heronphylogeny F•c. 5. DNA-DNA hybridizationestimate of her- includingall speciesincluded in Sheldon(1987a) and on phylogeny(Sheldon et al. 1995)with attached Sheldonet al. (1995).Branching topology is identical non-heronciconiiform outgroup. Branch lengths to thatof Figure3. Bran• lengthswere calculated by were calculatedby mapping 31 skeletalcharacters mapping 31 informativeskeletal characters using usingPAUP (length = 163, CI = 0.294,RI = 0.531). PAUP(length = 137, CI = 0.350,RI = 0.637).

numberof paralleland reverseevents is greater steps,yielding a total of 14 steps(length = 151, in the DNA-DNA hybridizationtree for cranial C! = 0.318, R! = 0.594). characters(n = 10, P < 0.022)but not for post- Skeletalcharacter homoplasy.--A winning-sites cranial characters(n = 8, P < 0.73). Parallel test revealed that the total number of homo- eventsare significantlygreater in the DNA- plasticsteps (i.e. parallelismsand reversals)is DNA hybridizationtree for cranial characters greaterfor the DNA-DNA hybridizationtopol- (n = 11,P < 0.012),but not for postcranialchar- ogy than for the skeletaltree (n = 18, P < acters(n = 6, P < 0.69). Reversestate-change 0.031). Separatewinning-sites tests for paral- eventsdo not differ significantlybetween trees, lelisms and reversals revealed that the total but the trend in probabilityvalues also sug- number of parallel eventsis greater for the geststhat the frequencyof reversalsis greater DNA-DNA hybridizationtree than for the skel- for cranialcharacters (n = 10, P < 0.36)than for etal tree (n = 17, P < 0.013),but the numberof postcranialcharacters (n = 10, P < 0.62). reversalevents does not differ significantlybe- Frequencyofhomoplastic evolution.--Given that tween trees (n = 20, P < 1.000). If the DNA- cranialcharacter evolution is morehomoplastic DNA hybridizationtree is correct,then the ma- than postcranialcharacter evolution in the jority of skeletal-characterhomoplasy is ac- DNA-DNA hybridization tree, we tested countedfor by the unusuallyhigh rates of par- whetherfrequencies of parallelismsand rever- allel evolution. salsdiffered among the three heronlineages: Homoplasticskeletal-character evolution is (1) tiger-heronsand the Boat-billedHeron, (2) not randomlydistributed among all of the skel- bitterns,and (3) day-heronsand night-herons. etal characters.Our analysesof cranial and A contingencyanalysis of the total numberof postcranialcharacters indicate that the total non-uniquestate changes revealed that cranial 134 MCCRACKENAND SHELDON [Auk, Vol. 115

TABLE2. Mean numberof homoplasticsteps per evolving under demonstrablydifferent forces characterfor cranial(n = 13) and postcranial(n = 18) skeletalcharacters in heron lineagesas esti- (seeBull et al. 1993,Miyamoto and Fitch1995). matedby DNA-DNA hybridization(Fig. 5). The most useful taxonomic characters,i.e. char- actersthat are mostlikely to be homologous, Post- are thosefor whichthe probabilityof unique Lineage Cranial cranial historicalorigin is high. Tiger-herons,Boat-billed Our findingssupport traditional views about Heron 0.769 0.667 the usefulness of taxonomic characters. Given Bitterns 0.462 0.667 that heronsuse their bills and palatal struc- Day-herons,night-herons 2.000 1.833 tures in different ways to obtain a variety of prey,and that they use their eyes to detectprey, their cranial structures must be under consid- and postcranialparallelisms and reversalsare erableselective pressure and would be expect- not distributed homogeneouslyamong the ed to evolveplastically. As such,it is not sur- three heronlineages (X 2 = 56.81,df = 2, P < prising that we found that cranial structures 0.001).Bittern DNA has evolved-25% faster are not useful taxonomic characters in herons. thanin day-heronsand night-herons and -44% Largelybecause of theinfluence of cranialchar- fasterthan in tiger-heronsand the Boat-billed acters,analysis of osteologicalcharacters plac- Heron. Evolutionof bittern cranialparallelisms and reversals, however, has been -78% less es tiger-heronsamong the day-herons,even frequentthan in day-heronsand night-herons thoughday-herons are moreclosely related to night-herons.In contrast,heron postcranial and -40% lessfrequent than in tiger-herons and the Boat-billedHeron (Table2). The evo- skeletalevolution appears to have been less lution of bittern postcranialparallelisms and plastic.Although there have beensignificant reversalshas been -64% lessfrequent than in changesin leg and wing length,particularly day-heronsand night-herons and approximate- amongday-herons and night-herons(e.g. Aga- ly equalto that in tiger-heronsand the Boat- mia, Bubulcus,Ardeola, Nycticorax, Nyctanassa), billed Heron. associatedpelvic and pectoralstructures ap- pear to have evolvedwithout the lossof phy- logeneticinformation. DISCUSSION Heronstraditionally have been divided into Phylogeneticestimation and skeletalcharacter fivegroups: day-herons, night-herons, bitterns, plasticity.--Sincethe time of Richard Owen tiger-herons,and the Boat-billedHeron (Bock (1866),hornology has been regarded as the key 1956, Hancock and Elliot 1978). Someof these to discoveringthe natural hierarchyof life. groupsdiffer substantiallyin cranialmorphol- Thus,the correctidentification of homologous ogy, apparentlyin responseto ecologicalforc- charactersand exclusionof homoplasticchar- es.This is particularlytrue of Boat-billedHer- actersfrom phylogeneticanalyses is oneof the on and night-herons.The Boat-billed Heron is greatestchallenges facing systematists. Darwin so differentfrom otherherons in bill morphol- (1859) recognizedthat the reliability of taxo- ogy that it showsremarkable convergence (e.g. nomiccharacters is inverselyrelated to the de- bill andpalate characters 1 to 4) with the Shoe- greeto whichcharacters have evolved for spe- bill (Balaenicepsrex). Apparently rapid, conver- cializedhabits. Features such as relativeposi- gent, developmentof scotopicvision and sub- tion, function,correspondence, and complexity sequentmodifications of orbital and bill struc- of charactersgenerally have been regarded as turefor nightfeeding in night-heronsand Boat- the hallmarksof adaptivespecialization (Re- billed Heron (as well as plumagesimilarities) mane1952). Bock (1967) further developed the explain why taxonomists generally have criteriafor recognizinguseful taxonomic char- lumpedthe Boat-billedHeron with the night- acters.He notedthat systematistsmust distin- herons,and why they also have removed night- guish betweenevolutionary forces associated heronsfrom the vicinityof day-heronsin clas- with the origin and modificationof characters sifications(Bock 1956, Payneand Risley 1976, and thoseassociated with naturalselection (i.e. Hancock and Elliot 1978). Compared with differential survival and reproduction),be- night-herons,other groups are remarkably causedifferent suites of charactersmay be similar in cranial morphology,particularly January1998] HeronPhylogeny 135 day-heronsand tiger-herons,and to a lesserex- cranialmorphology as they adaptedto night tent, bitterns. feeding.Such an explanation,although not ad- For cladisticand other methodsof analysis, heringstrictly to parsimony,is consistentwith the problemin estimatingthe correctphylog- the logicof Hennig's(1966) auxiliary principle, eny derivesfrom the fact that groupswith dif- whichholds that convergenceshould not be as- ferent cranial morphologiesare interleaved sumedin the absenceof contraryevidence (Wi- within the heronphylogeny. Thus, highly sim- ley 1981).Thus, cranial characterspresented a ilar day-heronsand tiger-heronsare separated problemat the outsetof our analysis,but upon by night-heronsand bitterns,and night-herons closerinspection, they actually helped us to and the Boat-billed Heron are separatedby formulate a more reasonableexplanation of day-heronsand bitterns.When cranial charac- heron evolution. tersare optimizedonto the phylogeny(Fig. 5), Molecularand morphological rates of evolution.- many convergentchanges are requiredto ac- The relationshipbetween molecular and mor- count for the similarity in the separated phologicalrates of evolutionhas been dis- groups,particularly the day-heronsand tiger- cussedsince the 1960s (Zuckerkandland Pau- herons. ling 1965),with the generalconclusion that the Althoughhomoplastic cranial characters are two rates are not related (Wilson et al. 1977). largelyresponsible for this result,we notethat Nonetheless, various authors have concluded these characterswould not necessarilyhave that when nucleotidesequences evolve rapidly, misledosteological analyses to the extentthat morphologicalcharacters also evolve rapidly theydid had:(1) the datamatrix been larger, or (Bosquetet al. 1992,Larson and Dimmick 1993, (2) the heronphylogeny been shaped different- Omland 1994). We found no strong evidence ly. If therewere morethan 33 charactersin the supporting a general relationshipbetween data matrix, the influenceof the homoplastic ratesof molecularand morphologicalevolution cranialcharacters might have been reduced. If in herons(Table 2). If cranialosteology in day- night-heronsand Boat-billedHerons or day- herons,tiger-herons, and bitterns actually has heronsand tiger-heronswere sister taxa, much converged,then bitterns exhibit the least of the convergentevolution would have been amountof changein cranialcharacters, which obviated.However, despite these factors, this are the mostlabile characters, even though they casein not likely to be an unusual or isolated haveby far the fastestrate of single-copyDNA incidentin which the most-parsimoniousmor- evolution.If day-heronsand tiger-heronshave phological tree is suboptimal. Congruence retainedtheir ancestralmorphology, which is analysisof crocodiles(Poe 1996), for example, morelikely the case,then high ratesof cranial demonstrated that the most-parsimonious evolutionhave occurredin night-heronsand morphologicaltree is suboptimal.Conversely, the Boat-billed Heron. Neither hypothesisis a circumstancein which a less-than-most-par- compatiblewith a causalmodel linking rates of simoniousmolecular tree might better describe molecularand morphologicalevolution. evolutionaryhistory occurswhen the stochas- Analysisof incongruence.--We have document- tic accumulation of nucleotide substitutions ed one examplein whichan analysisof incon- causeslong-branch attraction (Felsenstein 1978, gruence and explicationof character-state Hendy and Penny 1989). changescan be used to identifycorrelated char- In the caseof herons,a simplerexplanation acters, partition homoplasyamong lineages, for cranialcharacter evolution is that tiger-her- and highlightbasic evolutionary concepts and ons and day-heronsshare ancestralmorpho- processes.Such analyses should be conducted logical featuresrather than convergentones. whenever trees disagree. Particular effort Thisinterpretation is intuitivelyappealing be- shouldbe placedon identifyingcharacters re- causeit providesa hypothesisfor the adaptive sponsiblefor incongruence,establishing their specializationand radiationof heronlineages distributionand patternsof evolutionin differ- into new feedingzones in the early historyof ent parts of the tree, and thus explainingthe the group.Assuming a primitiveheron Bauplan overall effect these characters have on tree to- similar to day-herons,tiger-herons, and bit- pology.In thiscase, we foundthat cranialchar- terns, it is the night-heronsand Boat-billed actersintroduce bias into the morphological Heronthat have diverged most dramatically in databy virtue of their sharedprimitive states, 136 MCCRACKENAND SHELDON [Auk, Vol. 115 convergence,and possiblynonindependence as BLEDSOP,A. H., AND E H. SHELDON. 1990. Molecular adaptivesuites. As such,they shouldnot have homology and DNA hybridization.Journal of beenused to infer phylogeny.Had we tried to Molecular Evolution 30:425-433. solvethe problemof incongruenceby combin- BOCK,W. J. 1956.A genericreview of the familyAr- deidae (Aves). American Museum Novitates ing thesecranial characters in a character-con- 1779:1-49. gruenceassessment (Kluge 1989), as opposed to BOCK,W. J. 1967. The useof adaptivecharacters in a taxonomic-congruenceassessment (e.g. Bled- avianclassification. Pages 61-74 in Proceedings soe and Raikow 1990),the problemmay have XIV InternationalOrnithological Congress (D. goneundiscovered. But suchan optionwas not W. Snow,Ed.). Oxford, England, 1966.Blackwell available to us because some of the data were Scientific Publications, Oxford. DNA-DNA hybridizationdistances. Ardent pro- BOSQUET,J. S., H. STRAUSS,AND P. LI. 1992. Com- ponentsof the maxim of total evidencesimply plete congruencebetween morphological and would havethrown out the DNA-DNA hybrid- rbcL-basedmolecular phylogeniesin birches ization data, becausethey are viewed as non- and related (Betulaceae). Molecular Bi- ology and Evolution9:1076-1088. phylogenetic(e.g. Kluge and Wolfe 1993). How- BULL,J. J., J.P. HUELSENBECK,C. W. CUNNINGHAM,D. ever,because overwhelming evidence indicates L. SWOFFORD,AND P. J. WADDELL. 1993. Parti- that DNA-DNA hybridizationis an effective tioning and combiningdata in phylogenetic methodof phylogeneticinference (Caccone and analysis.Systematic Biology 42:384-397. Powell 1989, Bledsoe and Sheldon 1990, Powell CACCONE, g., AND J. R. POWELL. 1989. DNA diver- 1991,Sheldon 1994), not using its data would genceamong hominoids. Evolution 43:925-942. havebeen a violationof total evidence(de Quei- DARWIN,C. 1859. On the origin of speciesby means roz 1993).Our findingssupport the argument of natural selection,or the preservationof fa- that thepractice of combiningall availablechar- voured racesin the strugglefor life. JohnMur- acterdata into a singlephylogenetic analysis is ray,London. DE QUEIROZ,g. 1993. For consensus(sometimes). ill advised when some characters are biased or, SystematicBiology 42:368-372. in the caseof geneversus species phylogenies, FEDUCCIA,g. 1996. The origin and evolution of when differentsuites of charactersare tracking . Yale University Press, New Haven, Con- differenthistories (Bull et al. 1993, Miyamoto necticut. and Fitch1995, Page 1996). FELSENSTEIN,J. 1978. Casesin whichparsimony and compatibilitymethods will be positively mis- ACKNOWLEDGMENTS leading. SystematicZoology 27:401-410. HANCOCK,J., AND H. ELLIOT.1978. The heronsof the We thankAllan Baker,Anthony Bledsoe, Joel Cra- world. Harper and Row, New York. craft, JohnHarshman, Brad Livezey,Therese Mar- HENDY, M.D., AND D. PENNY. 1989. A framework kow, ThomasMartin, RobertPayne, Robert Raikow, for the quantitativestudy of evolutionarytrees. JackSites, Mike Stine,and two anonymousreviewers SystematicZoology 38:297-309. for theirhelpful comments on the manuscript;Clare HENNIG,W. 1966. Phylogeneticsystematics (D. D. Jonesfor her sequencingefforts and supportin the Davies and R. Zangerl, Translators.).University lab; Mike Stinefor providinga computerthat facili- of Illinois Press, Urbana. tated analysesof large data sets;and J. V. Remsen, KISHINO, H., AND M. HASEGAWA. 1989. Evaluation SteveCardiff, and Dave Willard for accessto speci- of the maximum likelihood estimate of the evo- mensat the LouisianaState University Museum of lutionary tree topologiesfrom DNA sequence Natural Scienceand the ChicagoField Museum.In- data, and the branchingorder in Hominoidea. stitutionaland financialsupport for this projectwas Journal of Molecular Evolution 29:170-179. providedby the LouisianaState University Museum KLUGE, A. G. 1989. A concern for evidence and a of Natural Science,School of Forestry,Wildlife, and phylogenetichypothesis of relationshipsamong Fisheries,College of Agriculture,Agricultural Cen- Epicrates(Boidae, Serpentes). Systematic Zoolo- ter, Louisiana Board of Regents, and NSF grants gy 38:7-25. BSR-8806890, BSR-9020183, and BSR-9207991. KLUGE, A. G., AND g. J. WOLF. 1993. Cladistics: What's in a word? Cladistics 1993:183-199. LITERATURE CITED LARSON,g., ANDW. W.DIMMICK. 1993. Phylogenetic relationshipsof the salamanderfamilies: An BLEDSOP,A. H., AND R. J. RAIKOW.1990. A quanti- analysisof congruenceamong morphological tativeassessment of congruencebetween molec- and molecularcharacters. Herpetological Mono- ular and nonmolecularestimates of phylogeny. graphs7:77-93. Journal of Molecular Evolution 30:247-259. MADDISON, W. P., AND D. R. MADDISON. 1992. January1998] HeronPhylogeny 137

MacClade:Analysis of phylogenyand character SHELDON,F. H. 1987b. Ratesof single-copyDNA evolution. Sinauer, Sunderland, Massachusettes. evolutionin herons.Molecular Biology and Evo- MADDISON, W. P., AND M. SLATKIN. 1991. Null mod- lution 4:56-69. els for the number of evolutionarysteps in a SHELDON,F. H. 1994. Advancesin the theory and characteron a phylogenetictree. Evolution45: practiceof DNA hybridizationas a systematic 1184-1197. method.Pages 285-297 in Molecularapproaches MCCRACKEN, K. G., AND F. H. SHELDON. 1997. Avian to ecologyand evolution(R. DeSalle,G. Wagner, vocalizationsand phylogeneticsignal. Proceed- B. Schierwater,and B. Streit, Eds.). Birkhauser ings of the National Academyof SciencesUSA Verlag, Basel,Switzerland. 94:3833-3836. SHELDON,F. H., AND M. KINNARNEY. 1993. The ef- MICKEVICH,M. F. 1978. Taxonomiccongruence. Sys- fect of sequenceremoval on DNA-hybridization tematicZoology 27:143-158. estimatesof distance,phylogeny, and rates of MICKEVICH, M. E, AND M. S. JOHNSON. 1976. Con- evolution.Systematic Biology 42:32-48. gruencebetween morphological and allozyme SHELDON,F. H., K. G. MCCRACKEN, AND K. D. STUEB- data in evolutionaryinference and character INC. 1995. Phylogeneticrelationships of the evolution.Systematic Zoology 25:260-270. Zigzag Heron (Zebrilusundulatus) and White- MIYAMOTO,M. M., AND W. M. FITCH. 1995. Testing crestedBittern (Tigriornisleucolophus) estimated speciesphylogenies and phylogeneticmethods by DNA-DNA hybridization.Auk 112:672-679. with congruence.Systematic Biology 44:64-76. SHELDON, F. H., AND L. A. WHITTINGHAM. 1997. NIXON, K. C., AND J. M. CARPENTER.1993. On out- Phylogenyin studiesof bird ecology,behavior, groups.Cladistics 9:413-426. and morphology.Pages 275-295 in Avian molec- OMLAND,K. E. 1994.Character congruence between ular evolutionand systematics(D. Mindell, Ed.). Academic Press, New York. a molecularand a morphologicalphylogeny for SIBLEY,C. G., ANDJ. E. AHLQUIST.1987. Avian phy- dabbling ducks (Anas). SystematicBiology 43: 369-386. logenyreconstructed from comparisonsof the genetic material, DNA. Pages95-121 in Mole- OWEN, g. 1866. On the anatomy of vertebrates. culesand morphologyin evolution:Conflict or Longman,London. compromise(C. PattersonEd.). CambridgeUni- PAGE, R. D. M. 1996. On consensus, confidence, and total evidence. Cladistics 12:83-92. versityPress, Cambridge, United Kingdom. SIBLEY,C. G., ANDJ. E. AHLQUIST.1990. Phylogeny PATTERSON,C., D. M. WILLIAMS, AND C. J. HUM- and classificationof birds. YaleUniversity Press, PHRIES.1993. Congruencebetween molecular New Haven, Connecticut. and morphologicalphylogenies. Annual Review SWOFFORD,D. L. 1991. When are phylogenyesti- of Ecologyand Systematics24:153-188. matesfrom molecularand morphologicaldata PAYNE,g. B., ANDC. J.RISLEY. 1976. Systematicsand incongruent?Pages 295-333 in Phylogenetic evolutionary relationshipsamong the herons analysis of DNA sequences(M. M. Miyamoto (Ardeidae). Miscellaneous Publications of the and J. Cracraft, Eds.). Oxford University Press, Universityof MichiganMuseum of Zoology150: New York. 1-115. SWOFFORD,D. L. 1993. PAUP:Phylogenetic analysis POE,S. 1996. Data setincongruence and thephylog- using parsimony,version 3.1.1. Illinois Natural eny of crocodilians.Systematic Biology 45:393- History Survey,Champaign. 414. TEMPLETON,A. R. 1983. Phylogeneticinference from POWELL,J. R. 1991. Monophyly/paraphyly/poly- restrictionendonuclease cleavage site maps with phyly and gene/speciestrees: An examplefrom particular referenceto the humansand apes. Drosophila.Molecular Biology and Evolution 8: Evolution 37:221-244. 892-896. WILEY,E. O. 1981. Phylogenetics:The theory and PRAGER,E. M., AND A. C. WILSON. 1988. Ancient or- practiceof phylogeneticsystematics. Wiley In- igin of lactalbuminfrom lysozyme:Analysis of terscience, New York. DNA and amino acid sequences.Journal of Mo- WILSON, A. C., S.S. CARLSON,AND T. J. WHITE. 1977. lecular Evolution 27:326-335. Biochemical evolution. Annual Review of Bio- REMANE,A. 1952. Die Grundlagendes natrlichen chemistry46:573-639. Systems,der vergleichendenAnatomie und der ZUCKERKANDL,E., AND L. PAULING. 1965. Evolu- Phylogenetik.Akademie Verlagsges,Leipzig, tionary divergenceand convergencein proteins. Germany. Pages97-166 in Evolving genesand proteins(V. SHELDON,F. H. 1987a. Phylogenyof heronsesti- Brysonand H. J. Vogel,Eds.). AcademicPress, New York. matedfrom DNA-DNA hybridizationdata. Auk 104:97-108. AssociateEditor: A. J. Baker 138 MCCRACKENAND SHELDON [Auk, Vol. 115

APPENDIXl. Heronspecies included in the analyses.a

Species Cochlearius cochlearius Boat-billed Heron*•- Tigriornisleucolophus White-crested Tiger-Heron* Tigrisomalineatum RufescentTiger-Heron*•- Tigrisomamexicanurn Mexican Tiger-Heron Zebrilus undulatus Zigzag Heron*•- Botaurus stellaris Eurasian Bittern* Botauruspoiciloptilus Australian Bittern Botauruspinnatus South American Bittern Botauruslentiginosus American Bittern*•- Ixobrychusfiavicollis Black Bittern Ixobrychuscinnamo- Cinnamon Bittern* meus Ixobrychussturmii African Dwarf Bittern Ixobrychussinensis Yellow Bittern Ixobrychuseurythmus Schrenck's Bittern Ixobrychusinvolucris Streaked Bittern Ixobrychusexilis Least Bittern*•- Ixobrychusminutus Little Bittern* Nyctanassaviolacea Yellow-crownedNight-Her- on*•' Nycticoraxnycticorax Black-crownedNight-Heron*•- Nycticoraxcaledonicus Nankeen Night-Heron* Gorsachius melanolo- Malay Night-Heron phus Gorsachius leuconotus White-backedNight-Heron Butorides striatus Green Heron*•- Ardeola ralloides SquaccoHeron Ardeolagrayii Indian Pond-Heron* Ardeola bacchus Chinese Pond-Heron Ardeolarufiventris Rufous-bellied Heron Syrigmasibilatrix WhistlingHeron*•- Pilherodiuspileatus Agamiaagami Agami Heron Egrettapicata Pied Heron Egrettatricolor Tricolored Heron* Egrettacaerulea Little Blue Heron*•- Egrettathula SnowyEgret*•- Egrettagarzetta Little Egret* Egrettasacra EasternReef Egret* Egrettaardesiaca BlackEgret Egrettarufescens ReddishEgret Egrettaintermedia Intermediate Egret* Bubulcus ibis *•- Egrettanovaehollandiae White-faced Heron* Ardea alba Great Egret*•- Ardea cinerea Grey Heron Ardea herodias *•- Ardeamelanocephala Black-headed Heron* grdea sumatrana Great-billed Heron* Ardea cocoi Cocoi Heron* Ardeapacifica White-necked Heron* Ardeagoliath Goliath Heron Ardeapurpurea Balaenicepsrex Leptoptiloscrumeniferus Marabou Stork Scopusumbretta Hamerkop Mycteriaibis Yellow-billed Stork Ciconia alba White Stork gnastomus oscitans Asian Openbill Stork Hagedashiahagedash Hadada Plegadischihi White-faced Ibis Plegadisfalcinellus GlossyIbis*•- Ajaia ajaja RoseateSpoonbill Phoeniconaias minor LesserFlamingo •Asterisksindicate species with DNA-DNA hybridizationdata (Sheldon1987a, Sheldon et al. 1995);crosses indicate species with vo- calizationdata (McCrackenand Sheldon1997). January1998] HeronPhylogeny 139

APPENDIX2. Winning-sitestest scores. Values are numberof paralleland reverse steps for eachpossible statechange of Payneand Risley's(1976) skeletal characters when optimized most parsimoniously onto DNA-DNAhybridization tree (Figs. 1A and 5) and skeletal-charactertree (Fig. 4).

DNA tree Skeletaltree Step difference Statechange Parallel Reverse Parallel Reverse Parallel Reverse Bill shape 0-•1 2 0 0 0 2 0 Palatine shape 0-•1 3 0 0 1 3 -1 Palatine emargination 2--•1 3 1 3 3 2 0 1--•0 3 3 4 1 -1 2 2--•3 2 0 0 0 2 0 Palatine lateral process 1-•0 5 0 4 0 1 0

Interorbital foramen 2-•0 4 0 0 0 4 0 2--•1 2 0 0 1 2 -1 2--•3 2 1 0 2 2 -1 Supraorbital foramen 2--•1 3 1 2 1 1 0 1--•0 3 2 2 1 1 1

Lacrimal size 1•0 3 1 3 0 0 1 1--•2 0 0 0 0 0 0 Lacrimal ventral projection 2--•3 0 0 0 0 0 0 1--•2 3 1 4 0 -1 1 0--•1 0 0 2 0 -2 0 Lacrimal lateral groove 0--•1 5 1 4 2 1 -1 1--•2 0 0 0 0 0 0 Ectethmoid 1--•0 4 0 3 0 1 0 Ectethmoid tubercle 0-•1 6 0 3 3 3 -3 1-•2 0 0 0 0 0 0 Ectethmoid ridge 0--•1 4 1 3 0 1 1 Basitemporal ridge 0--•1 0 3 0 0 0 3 Axis shape 2--•1 0 3 0 0 0 3 1-•0 2 2 2 0 0 2

Lateral canal 0-•1 6 0 2 2 4 -2 Rib facets 0--•1 2 4 2 1 0 3 Notches 0--•1 2 0 2 0 0 0 140 MCCRACKEN AND SHELDON [Auk, Vol. 115

APPENDIX 2. Continued.

DNA tree Skeletaltree Stepdifference Statechange Parallel Reverse Parallel Reverse Parallel Reverse Manubrial length 0•1 0 1 2 1 -2 0 1-•2 5 1 3 2 2 -1 Sternocoracoidalprocess 0-•1 2 2 2 1 0 1

Sternal facet 0-•1 0 0 0 0 0 0 External spine 0•1 3 1 2 2 1 -1 1 -•2 3 0 2 2 1 -2 2•3 3 0 2 2 1 -2 Internal spine 0-•1 3 1 2 3 1 -2 1•2 2 1 2 0 0 1 2•3 0 0 0 0 0 0 Deltoid crest shape 0-•1 2 0 2 0 0 0 Deltoid crestheight 0-•1 4 0 3 1 1 -1

Pneumatic fossa 0-•1 5 1 5 1 0 0 1•2 0 0 0 0 0 0 Ligamental furrow 0•1 2 0 2 0 0 0 Iliac crestshape 0 -• 1 3 2 4 0 -1 -2

Posterior iliac crest

Paraphysesfusion 0-•1 4 0 4 0 0 0

Iliac recess 0•1 4 3 5 1 -1 2 Ischiopubic symphysis 0-•1 0 0 0 0 0 0 Intercotylar prominence 1-•0 0 0 0 0 0 0

Metatarsal foramen ni ......

Not informative. January1998] HeronPhylogeny 141

APPENDIX3. Parallel,reverse, and total homoplastic steps for eachof Payneand Risley's (1976) skeletal char- actersin the DNA-DNA hybridizationtree (Fig. 5).

Tiger-herons, Boat-billedHeron Bitterns Day-herons,night-herons Character Parallel Reverse Total ParallelReverse Total Parallel Reverse Total

Total cranial 9 1 10 5 1 6 16 10 26 Bill shape I 0 I 0 0 0 0 0 0 Palatineshape 1 0 1 0 0 0 0 0 0 Palatineemargination 1 0 1 1 0 1 1 4 5 Palatinelateral process 0 0 0 0 0 0 2 0 2 Interorbital foramen 1 0 1 1 0 1 5 0 5 Supraorbitalforamen 2 0 2 0 0 0 0 3 3 Lacrimal size 1 0 1 0 0 0 0 0 0 Lacrimalventral projec- tion 0 0 0 1 0 1 1 0 1 Lacrimallateral groove 0 0 0 0 0 0 2 1 3 Ectethmoid 0 0 0 0 0 0 0 0 0 Ectethmoid tubercle 1 0 1 1 0 1 4 0 4 Ectethmoidridge 1 0 1 1 1 2 1 0 1 Basitemporalridge 0 1 1 0 0 0 0 2 2 Total postcranial 9 3 12 8 3 11 21 12 33 Axis shape 0 1 1 1 1 2 1 3 4 Lateral canal 1 0 1 1 0 1 3 0 3 Rib facets 0 1 1 0 1 1 0 2 2 Notches 1 0 1 0 0 0 0 0 0 Manubriallength 1 0 1 1 1 2 3 1 4 Sternocoracoidalprocess 0 0 0 0 0 0 2 1 3 Sternal facet 0 0 0 0 0 0 0 0 0 External spine 1 0 1 1 0 1 4 1 5 Internal spine 0 0 0 1 0 1 3 2 5 Deltoid crestshape 0 0 0 1 0 1 0 0 0 Deltoid crestheight 0 0 0 1 0 1 1 0 1 Pneumatic fossa 2 0 2 1 0 1 0 0 0 Ligamentalfurrow 1 0 1 0 0 0 0 0 0 Iliac crestshape 0 1 1 0 0 0 2 1 3 Posterior iliac crest ...... Paraphysesfusion 1 0 1 0 0 0 0 0 0 Iliac recess 1 0 1 0 0 0 2 1 3 Ischiopubicsymphysis 0 0 0 0 0 0 0 0 0 Intercotylarprominence 0 0 0 0 0 0 0 0 0 Metatarsal foramen • ......

Not informative.