Cladistic Taxonomy

1995 POLNTS OF VIEWSSTEMATIC BIOLOG 
schoois ot taxonomy (Fig. 1) are as foliows. 
Aristotelian taxonomy proceeds by logical subdivision, in which each member of a Cladistic Taxonomy, Phylogenetic Systematics, and 
Evolutionary Ranking 
pair of taxa is characterized, respectively, by the presence and absence of a chosen 
N Dt feature. All present attempts to derive a 
taxonom from an identitication key reflect 
this process. In Linnaean taxonomy, there 
is an explicit attempt to distinguish the im- 
portant (stable, essential) properties from 
the unimportant (variable, nonessential) 
properties. In traditional taxonomy, groups 
are reconstructed based on perceived sim-
ilarities and ditterences among taxa. Qui- 
narian taxonomists (eg., MacLeay, 1819) 
looked for idealistic groupings in circles of
five, supposed to reveal the harmonious 
MARTIN L. CHRISTOFFERSEN 
nEto a SISt£MT ITA t Ecoioga. uniersuzae keaETa. ia Paraiva 
5S050-900. joào Pessoa. Paraiba Bras1l
A 
The anaent discipline of biological tax 
onomr has been veT slow to incorporate phylogenetic representations (Gritfiths,
maior shifts in worid views throughout the 
millennia. imperiious to the derision of 
saentists trom the more giamorous fields
0 research. marnr taxonomists today sim- onvmy tied to Linnaean categories, 
and re- 
pi take tor graried secular traditions of dundant taxon names (Christoftersen, 
describing and naming the diversity of na- 
Te Ther mav persist stoically for a life- conflict with evolutionary approaches. 
The 
time in such a sel:-appointed descriptive codes thus help perpetuate essential1stic
role, avoiding theor, philosophy, and ex taxonomic traditions rather than promote 
pianation. Some of these taxonomists may Conceptual evolutionary
nnovations.
rated by the codes, simply conflict with 
1974a, 1974b, 1976). For exampie, manda- 
tor categories, the names o: genera as 
parts of binomiais, typification and syn- 
FiGURE 1. A possible phyiogenv o: intellectual lin- 
eages in biological taxonorn. A-M. sequence of an-
cestor-descendant lineages; N monophyletic taxon of 
multiple lineages or single lineage o 11nterbreedng 
populations. A = Aristotelian taxonomy; B = Linnae- 
an (essentialistic, typolog1cal) taxonomy, C = tradi- 
tional taxonomy; D = extinct qunarnan taxonomy; E 
conventional taxonomy; F= 0mnispeciive tcompi- 
latory, practical, utilitarian) taxononir, G = natural Od LdXOnomy nvolves interpretation of 
taxonomy; H = phenetic (numencal taxonomy (phe similarities and differences as reflecting 
netics);= orthodox taxonomy,! = evoiunonary degrees of phylogenetic relationships. Om-
(Mavrian, Simpsonian, sVntheic, siTICTetistic. gradis- 
tic, eclectic) taxonomy (phyletics), K = Hennigian tax- 
onomy, L phylogernetic taxonOny iphylogenetic cia 
distics), M=ciadisti: taonomy patterr. 
methodoiogica., transtormed ). = phyiogeneuc svs 
tematics (pnvlogenetics 
and lawful relations of numbers as evi- 
dence of the rational plan of creation. In-
Corporating evolutionary theory, conven- 
1987; de Queiroz and Gauthier, 1992) all 
nispective taxonomists explicity reject arny 
connections between a practical and utili- 
tarian taxonomy and the processes 
thought to be responsible for biological di-
versitt eS. Biackweider, 1964). In natural 
taxonom, groups are supposed to be dis- 
COvered in nature rather than fabricated in 
venture intuitive classitications tor their 
CONCETUAL LINEAGES
named groups bu: will often delegate to 
otners the task 0: derivVing evolutionar 
meanings rom the: propOsals. 
EvolunOnarv concepts have still not pen 
etrated tne core 0: nomenclature. The in- tlicting conceptual systems. Following 
ternationa. coaes (internationai Commis- Hull's (1984) and Mishler's (198:) analog 
Sion on Loological Nomnenclature, 1985; 
Lnternat1onal Botanica Congress, 1988; in- research groups, rather
than being defined 
ternational Associaion of Microbial Soci- by the presence of Some necessary and sut 
eties, 1992 are totaly couched in a tradi- 
ficient set of shared ideas, are viewed as 
tional Linnaean ramewOrk developed 
more than 100 vea:s before the widespread 
acceptarnce oi evOiutionary ideas. Purport- 
relations with other lineages. I propose a 
ediy not to interIere with taxonomic free- 
dom, the codesprovide no rules for the svstems of biological taxonomr (Fig.
1). Fo: 
Tecógnition and derinition of taxa and cat- 
egores et the available rules significantly 
Constrain taxonomic practice by tving tax- (individual spokespersons) 
on the phylo-
ot names to categorical ranks. This struc-
ture interteres wjtn the codes own avowed who provided a 
numerical cladistic studv
goals of providing expiicit, universal, and of phylogeneticists 
and a review' of prei 
stablenames tor taxonomy because a taxon ous single-character classifications
of the 
ame must be changed every time it is three main contemporary schools of tax 
placed in a different category (de Queiroz onom. 
and Gauthier, 1994). Furthermore, several 
taxonomic conventions, variously incorpo- atics, and classification have been advocat- 
laxonomists, like other segments of the 
scientific community, are presently divid- 
ed into several tactions that support con- 
1970; Griffiths, 1974a; Wile, 1981: de the mind of the taxonomist. Phenetic tax- 
Queiroz, 1988). When these denominations onomists attempt to quantify data and es-
become interehangeably qualined by such tablish groups by overall similarity. In or-
terms as traditional, numerical, phenetic, 
evolutionary, cladistic, and phylogenetic used to access taxa (similarity, diversity, 
(Fig. 1), their meanings become fmulti�ari- Size of gaps, ecology, behavior, etc.). In 
ous, extensively Overlapping. and sutti- evolutionary taxonomy, species are rede-
Ciently confusing So as to lose much of fined as evolutionary units (MayT, 1942, 
their heuristic and interpretative value íct. Simpson, 1961), and phenetic, Patristic, Charig, 1982; Hill and Crane. 1982; de and cladistic data are combined into a Sin- 
Queiroz and Donoghue, 1090b: Nixon and gle taxonomic system (e.g., May, 1981; 
Wheeler, 1990). lerms and concepts are 
necessarily context bound and shouid be 
allowed to change through time. I provide granted a central role at all levels in the 
here successively more inciusive defini- taxonomic hierarchy. in the last two de-
tions for the basic concepts of taxonomy, 
systematics, and Classification. I hope my 
assignment of several commonly used Mishler, 1987; de Queiroz and Donoghue, 
qualitying terms to distinct conceptual 1990a) (Fig. 1). Pattern cladists are empir systems (Fig. 1) wll reduce ambiguity, 
even if total agreement is not possible. 
Brief haracterizaions ot the sereral a taxonomy (Brady, 1985; Nelson, 1985. 
with biological phylogenies, tnese difterent 
thodox taxonomy, multiple criteria are 
intellectual lineages, with strong historicai 
Conerence, social! cohesion, and adversaria. 
tentative phvlogeny tor these intellectua. 
those that would have prererred to see 
characters (shared ideas) and Characters 
Stuessy, 1987, 1990). In Hernigian taxono-
my, the priniple of common descent is genetic tree, I deier to Carpenter (1987: 
cades, a phiosophical split has developed 
within phylogenetic systematics e.g 
Different concepts of taxonomy, system-
ICists that avoid all assumpthons and pre- 
Conceptions about process in constructing ed by various authors (e.g., Simpson, 196. 
Blackwelder, 1967; Mayr, 1969; Nelsor mal endii nrufpb bitnet. 
SYSTEMATIC BIOLOG VOL. 1995 POINTS OF VIEW 
42 
avoiding the time axis and the production practices. Cladistic taxonomy mav be iden-tified with what has been called the taxic 
Rieppel, 1988b). Phyiogenetic taxonomists (Hennig. 1966:6). Characters are instanta 
are evoiutionary theorists that deduce the neous morphologies (de Queiroz, 1985: 
most useful taxonomic concepts and meth- 296) that are compared among "specimens 
ods from general evolutionary processes at similar