Evidence-Based Taxonomy: Labels as Illocutionary Acts

Abstract

Concepts in science have an important role: They delimit and specify objects, activities, processes, and abstract entities. When terms are diffuse, mean different things to different persons, and lead more to qualifications than demarcation, they cease to be concepts and may become labels, which are informal alternative designations. There are many labels in science and they have become abundant in taxonomy: α-taxonomy, integrative-taxonomy, iterative-taxonomy, etc., are only a few examples. α-taxonomy is a negative label that obtained popularity at the same time the term α-diversity became popular in ecology. The label α-taxonomy conveys a negative meaning to taxonomy because the nature of its evidence—originally morphological—is seen by many as “merely descriptive” and, thereby, supposedly inferior to other forms of evidence. This has contributed to substantial and unwarranted damage to the status of this science and to the careers of taxonomists. The recent history of methodologies for species delimitation shows that what some have considered of low value (morphology), compared to “new” data (molecular), is in many cases the critical factor to delimit species. We propose to eschew these kinds of labels and simply refer to taxonomy to avoid stigmatizing of any kind of practicing taxonomist, whether focused on morphology, cytology, molecular biology, or other fields of biology. Taxonomy implies the use of the current best evidence, theories, and methods to demarcate species and their relationships.

1. Background

Knowing the identity of the organisms that surround us as well as those that may exist beyond our immediate vicinity is the basis of many disciplines, scientific or otherwise: agriculture, pharmacopeia, ornamentation, landscaping, etc. Before the Renaissance, the term Natural History included a multitude of activities, many of them outside of the limits of Natural History as we now know it. It was the development of a group of scholars during the Renaissance that gave Natural History its current distinctive outlook: The goal to discover and represent, with a specific terminology, all organic beings over the surface of the World. As pointed out by Ogilvie [1] (pp. 6), “Originally, these descriptions were pictorial, but soon a technical descriptive language was elaborated that eventually took precedence, within the community, over pictures.” This activity was crystallized in the Linnaean system of classification and nomenclature in the eighteenth century [2]. One may say that the Linnaean system was to Natural History what Avery’s discovery was to Molecular Biology [3,4,5]. Before Avery’s experiments, it was commonly assumed that proteins were molecules that carried genetic information; it was logical, as they had enough variation to account for the variety of life [5]. DNA, with only four different units, was concluded to be insufficient for corresponding to such variability. The truth, of course, turned out to be the opposite, and it opened the field to new problems and questions that could not have been formulated without it. In the case of Linnaeus, changing the way organisms were organized from entries in a dictionary [6] to nested hierarchical groupings—i.e., an implicit genealogical system [7]—eventually gave way to the search for mechanisms of evolution.

Linnaeus’ system, ethnobotanical taxonomy [8,9], and everyday common sense use vague homology notions to give coherence to the natural world under operational concepts such as “affinity”, “similarity”, and “differences” [10]. Species of insects are compared with other species of insects, vascular plants with vascular plants, etc., and are included together in their respective classifications, implying a notion of relationship. Lamarck, Mendel, and Darwin consolidated this perspective by proposing mechanisms to explain organic genealogy. As a result, present day discoveries and naming of taxa are explicit—although not necessarily well resolved—hypotheses of relationship. That these hypotheses may be preliminary or in need of greater support does not change the substantive evolutionary basis of that research [11].

Terms for concepts play the role of identifying objects, functions, or ideas, and their meaning and application suffer the influence of time, methodological advances, social evolution, and fashion. A good instance of the latter is the fact that only a few institutions retain departmental names such as botany, geology, entomology, or zoology. Most have been replaced by modern-sounding names such as “Integrative Biology”, “Evolutionary Ecology,” or “Evolutionary Biology”. Since Darwin, all of biology is under the paradigm of evolution and, as such, “evolutionary” can be seen as an unnecessary sobriquet. Saying taxonomy or biology alone, however, does not imply that it is currently practiced as it was practiced in Linnaeus’ times or even before.

The first proposal of the term taxonomy in reference to a method of classification can be found in De Candolle [12] (p. 24): “… de savoir si ce que nous observons l’a déjà été par quelqu’ autre? Ce service éminent … je désigne sous le nom de Taxonomie botanique.” (…how do we know if… what we have found [e.g., a species] has already been [discovered] by somebody else? This outstanding service … I designate it’s name as botanical Taxonomy). In De Candolle’s time, thirty thousand plant species were known and he expected the total number in the world to be sixty thousand. For De Candolle, the word taxonomy had an emphasis on the “retrieval” and reference aspects that any naming system would (or should) provide [13]. The name, beyond singling out a kind of organism, permits the recovery of known data on morphology, distribution, and so forth. This, however, is only a limited part of the function of names in the Linnaean system [11], as we presently use it. Crowson [14] disputes the necessity of using the term taxonomy when the word “classification” covers the same field.

2. Labels in Taxonomy

More than one hundred years after De Candolle’s paramount essay, the botanist W. B. Turrill [15] created the label “alpha-taxonomy” to designate a form of preliminary work performed by taxonomists, or in his own words: “The aim of the alpha taxonomist must be to complete the preliminary and mainly morphological survey of plant-life, and much remains to be done on these lines.” He contrasted it with an idealized “omega-taxonomy” achieved through the practice of beta, gamma, and other sequential letters of the Greek alphabet, denoting increasingly informative taxonomic systems [16].

In Turrill’s time, the amount of data that could be obtained from cytology, ecology, genetics, etc., increased to a level that only allowed complementing the information from morphology as the basis of taxonomic decisions, that is, decisions on species demarcation and relationships. Moreover, Turrill’s papers were a call to taxonomists to include such information arising from emerging technologies and disciplines in their taxonomic work. However, Turrill’s appeal to taxonomists was not original. Two hundred years earlier, in 1736, Linnaeus (see [2] (pp. 154–156) and [17] for an English translation), in explaining his method, demanded under paragraph “V. Attributes”, the inclusion of data on birth, growth mode, breeding, distribution, diet, habits, temperament, and gross and microscopic anatomy, among other data. Had he known of the existence of DNA, he would surely have added it to the list. In other words, he proposed what Hennig later christened holomorphology [18], a term that did not gain popularity among practicing taxonomists. Neither did the more euphonic term phenome [19], which has an identical meaning.

The labels used by Turrill, although occasionally mentioned in general and monographic botanical works, e.g., [20], do not reappear in the zoological literature until Mayr, Linsley and Usinger’s treatise on systematic zoology resurrected them [21], albeit without attribution. Mayr had previously [22] distinguished several steps in any taxonomic work: collecting, identifying, describing, etc., without mention of the particular stages of taxonomic resolution that the terms alpha, beta, etc., referred to. In fact, Mayr et al. [21] use the terms alpha and beta but change omega to gamma, and all three terms are used in a sense that is very different from that of Turrill. In Turrill’s definition, the Greek alphabet denotes increased amounts of empirical evidence from morphology, cytology, genetics, etc. In Mayr et al. [21], Greek letters stand for different levels of resolution in the classification procedure. Mayr et al. [21] (p. 19) defined the stages of taxonomy as follows: “Alpha taxonomy refers to the level at which the species are characterized and named; beta taxonomy to the arranging of these species into a natural system of lesser and higher categories; and gamma taxonomy to the analysis of intraspecific variation and to evolutionary studies.” Their definitions, however, did not have great impact on the taxonomic community. Between 1953 and 1969, the date of another landmark publication by Mayr, there is not a single mention of alpha-taxonomy in the restricted sense of Mayr et al. [21] either in Zoological Record (ZR) or Web of Science. It may be safely asserted that the term alpha-taxonomy was not used by the taxonomic community until the mid-1970s.

Mayr [23] presents a rather different definition from his previous publication. This time, the wording seems to have had greater impact within the biological community and several hundred publications using “alpha-taxonomy” may be found in the Zoological Record (ZR) and Web of Science databases up to the present (216 publications in ZR, 13 May 2022). It is a matter that needs investigation whether this acceptance of the terms is related to the proposal and adoption of the terms alpha, beta, and gamma diversity in Ecology at that time [24].

As unnecessary as the term alpha-taxonomy may be, increased arbitrariness in its definition has led to the term’s progressively increased ambiguity, culminating in statements such as [25] (p. 422): “Alpha taxonomy deals with the species category, beta taxonomy with higher categories.” These authors confound species as a taxon and species as a category, concepts distinct in the taxonomic literature. Additionally, their definition may lead to the pointless categorization of papers treating various taxa. There is no substantial difference in methodology in discovering a new species, genus, or family as they are all based on the evaluation of organismal homologies. Examples of this arbitrary use of the terms alpha, beta, and gamma taxonomy can be extended to dozens of publications. This misunderstanding is, in our opinion, the reason why several authors still accept this arbitrary designation of a taxonomist’s work. It may be concluded that the terms alpha, beta, and gamma are labels more than concepts as their meanings are not universally defined and alpha at least carries a substantially negative connotation. This state of affairs was anticipated by Blackwelder [26] who, in his encyclopedic treatise on taxonomy (pp. 4, 14), refers to these and similar terms as “derogatory in tone, ostentatious in implication, or pedantic in application” to conclude that “The use of alpha and beta taxonomy for the descriptive taxonomy and classification, respectively, seems merely to substitute symbols for self-explanatory terms.”

These labels have persisted in their negative incarnation, especially for the alpha taxonomy stage that has become degraded to the idea that many biologists presently hold [27] (p. 15): “When collecting and “naming” were believed to be the essence of taxonomy, almost any untrained person could become a specialist in a group the knowledge of which was still at the level of alpha taxonomy.” The idea that naming is just a “stamp collecting” activity has been widely spread within the scientific community (see [28] for a detailed history of “stamp collecting” applied to study of biodiversity), with the result that researchers engaged in descriptive taxonomy are held in low esteem despite a vehement defense occasionally mounted by some [29,30,31]. Another metric of its toxic effect is the declining number of taxonomists employed in museums, universities, and research centers [32,33], notwithstanding the disputable assertion of an increase in the number of taxonomists in recent times [34,35]. Although no detailed data are available on the overall trend of active taxonomists over the last 40 years, some data clearly point to a drastic decrease in their numbers. In 1992, there were about 557 Arthropod taxonomists in Spain (then with 39 million inhabitants) [36]. The European red list of taxonomists [37] lists about 1000 insect taxonomists in 2021 (for a European population of about 750 million inhabitants, according to statisticstimes.com—viewed on 7 August 2022 [38]). Additionally, the diversification of publications by taxonomists beyond their “taxonomic specialty” as a way to survive in academia may be a reason why not all of the taxonomist’s time is devoted to taxonomy.

More recently, some have looked for better-sounding labels such as Integrative Taxonomy [39], but see [40]: Morphology-Based Alpha Taxonomy (MOBAT [41]), Numeric Morphology-Based Alpha Taxonomy (NUMOBAT [42]), and iterative taxonomy [43]. In the field of phylogenetic inference, similar labels are occasionally found, such as total evidence [44] when one intends to mean simultaneous evidence [45,46]. Moreover, while Hennig [18] intended phylogenetic systematics to integrate cladistic analyses and formal classifications, some identify themselves as phylogenetic biologists rather than phylogenetic systematists, presumably in an effort to distance themselves even more from “alpha” taxonomy [47]. Labels alone cannot change the concept or practice of taxonomy that will remain rigorous, and no more or less integrative, than any other branch of science.

The “dark taxon impediment,” referring to a massive number of undescribed species, is an obstacle to fields from ecology to conservation. Some propose shortcuts in taxonomy to accelerate species discovery, such as the COI barcode clusters (Barcode Index Numbers “BINs”) used by Sharkey et al. [48]. Beyond issues of instability, insufficiently informative diagnoses, and reliance on proprietary software, their approach adds to a different problem: the “superficial delimitation impediment” [49]. It is more work to correct insufficient species descriptions than to adequately describe species in the first place. Users of taxonomic information may simply want to identify species, but taxonomists are concerned with species as testable hypotheses and the quality of evidence supporting them. Increasingly sophisticated algorithms make it possible to base species on multiple data sources, avoiding “minimalist revisions” that sacrifice scientific rigor for speed.

As a final remark to this section, a parallel can be drawn between the establishment of the diagnosis of a disease and the delimitation of organisms as new species. A patient is not interested in the plethora of analyses and tests that can be performed, whether they are preliminary, exploratory, or advanced. What s(he) is really interested in is the diagnosis and the type of therapy that can be established. The potential number of tests that a patient can undergo is unlimited, but once a clear diagnosis has been reached, what needs to be undertaken is to take action and apply the relevant therapy as soon as possible. This is what is known as evidence-based medicine: “the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients” [50] (p. 397). Translated to the field of biodiversity, we could say that “Taxonomy implies the use of the current best evidence to demarcate species and their relationships”. No other qualification is needed.

3. Labels as Illocutionary Acts

In 1962, the linguistic philosopher J. L. Austin published, posthumously, “How to do Things with Words”, based on a set of lectures given at Harvard in 1955 [51]. In this book, Austin introduced the concept an “illocutionary act” as a class of linguistic sentences that are not statements of truth or falsity, but that perform an action. A typical example is “I do” in a wedding, where the pronouncement of these words has the effect of instituting an interpersonal social contract. Dörge [52] has performed a thorough revision of Austin’s conception of speech acts and gives the following concise definition: an act is an illocutionary act if its application results in “(1) certain conventional consequences…” and that (2) “there is a hearer in which [the] “uptake” [of the act] is “secured” [52].

Beyond linguistics, the concept of “illocutionary act” has been applied as a key aspect in legal and philosophical considerations of hate speech (e.g., racism) and in pornography to judge speech and its consequences under the law in the U.S.A. (see [53,54] for some representative discussions).

As remarked by N. J. Nersessian [55] (p. IX), “Novel concepts arise from attempts to solve specific problems, using the conceptual, analytical, and material resources provided by the cognitive-social-cultural context in which they are created”. And while this may apply to the proposal by Turrill, their reformulation by Mayr had more the effect to demarcate a kind of ghetto of supposedly “poorly justified and weak science”. It is therefore not strange that taxonomy has an “image problem” [56] and that those labels—besides contributing to conceptual confusion—do not help identify the scientific foundation of species exploration [47].

When terms are not clearly defined, they may cease to be scientific concepts and mutate into illocutionary acts that are in some cases beneficial and in others harmful. In our present case, terms such as “integrative taxonomy” seek to convey the idea that taxonomy is a modern discipline whereas terms such as “alpha taxonomy” inflict harm because they evoke a kind of work that “… is often regarded by university students, and by many professionals, as one of the most boring and least necessary areas of biology.” [57].

Take, for instance, the term “biodiversity”, defined as “the study of organisms from the genes up to the ecosystem” [58]. This is the traditional definition of taxonomy. But as “identifiers” become old, new terms appear to give them new life by simply replacing them. However, the opposite happens with other concepts. For instance, although the concept of genes has changed profoundly since first issued by Johanssen [59], we still use the same word even though it is necessary to consult a modern biology textbook to obtain a realistic understanding of its present-day and expanded meaning [60].

Other terms have been contemptuously used in taxonomy, such as “essentialism” and “typology” [61,62]; review in [63]. As pointed out by Wheeler and Valdecasas [64] “Perhaps because taxonomists use “type” specimens as standards for scientific names, the shared word root lent subconscious credence to Mayr’s claims. The claim was ludicrous in the first place given that taxonomists were among the first biologists to confront the problem of variability [65].” The meaning and reception of these two terms deserve its own analysis [66,67].

The labels alpha, beta, and gamma taxonomy established artificial steps in the continuous workflow of a scientific discipline, thereby encouraging discrimination within the taxonomic community among activities of supposedly greater or lesser scientific rigor. Naming is falsely taken by many as pure administrative work, such as that of notaries or magistrates; we have even seen an ad for a position in taxonomy that specified “not an alpha-taxonomist”. It has been argued that symbolic aspects of a person’s name (initials such as P.I.G. or D.I.E.) may have a negative effect on their wellbeing ([68,69], but see [70,71] for a rebuttal); the possibility that certain labels in taxonomy may have led to seriously negative consequences for professionals should be further investigated. How many taxonomists, specialists in their specific group of organisms, and bearers of a unique, slowly accrued knowledge [72], have been ostracized by colleagues or administrators who seek their own increased relevance in the modern, marketing-based, and political academic world? Moreover, what are the long-term consequences of the negative labeling viz-à-viz the “biodiversity crisis”?

In addition, labels are not equivalent to scientific concepts. The development of technical terms in any discipline is a requirement for theories to attain “great precision, wide scope, and high empirical confirmation” [73]. Labels such as alpha taxonomy, integrative taxonomy, and the like lack the rigor and theoretical content that add precision to science, such as homology [11]. They are better avoided as they do not provide any special insight and, worse, may result in an ambiguous, arbitrary sense being attributed to taxonomy. The same may be said of varied uses of the terms taxonomy and systematics (systematic biology). Attempts to relegate taxonomy to the “bookkeeping” aspects of classification and nomenclature [22], while imbuing systematics or biosystematics with a focus on evolution, have only confused matters. We propose that if both terms are used that they are to be understood as synonyms referring to one and the same science, unqualified and in all of its phases.

Due to the present reality of species extinction, ecosystem degradation, and climate change, the need for thorough, scientific taxonomy is greater and more urgent than ever. We urge governments and institutions to appropriately resource taxonomy in underexplored regions, least well-known groups of organisms, and those taxa most severely impacted by human activities. It is important that a full record of the diversity of life on Earth be made before it has been decimated to better understand both evolutionary history and the biosphere as it existed at the dawn of the Anthropocene. We urge leaders of museums and universities to reverse the tragic decline of taxonomists and taxonomic research [74]. Finally, we urge biologists, including taxonomists themselves, to abandon the use of pejorative labels and to reassert modern, rigorous taxonomy in all its phases