Analyses

All analyses were carried out in R version 4.1.0 [15]. Model selection was carried out via backwards selection, dropping non-significant terms in every step. The real identity of the interviewees was maintained anonymous in all cases, when interviewee ID is used, it was simply a unique number ranging from 1 to “n” (corresponding to the n^th respondent).

Demographics

The respondents can be divided into groups according to gender identity, the country where they currently work, and academic background. Around 70% of the respondents were male, circa 28% female, and circa 1% gender diverse (Q1). Around 70% of respondents work in Europe or North America (Q2; S1 File: S1 Table); the two countries with the most respondents were the USA and Germany. Combining the countries in main regions, we have the following proportions: North America ~32%, Europe ~36%, Latin America ~16%, Oceania ~8%, Asia ~5%, Africa ~1.5%, Middle East ~1.5%. This classification in regions was used in further analyses, but due to the low number of responses from the Middle East, they were included in the category Asia.

About half the respondents work in universities (Q3; S1 File: S2 Table), with circa 27% working in museums, and 14% in other research institutes. The most common positions/jobs of the respondents (Q4; S1 File: S2 Table) were professor or lecturer (~31.5%), researcher (~31%, including postdoctoral researchers), and curator (~10%). About 10% of the respondents in the professor/lecturer category also had duties as curator or collection manager. Over 80% of respondents hold a doctoral degree (Q5; S1 File: S2 Table). Around 55% of respondents acquired their highest title (Q6) at least eleven years ago, while circa 30% acquired it from three to ten years ago, and circa 15% acquired it less than three years ago.

Regarding taxonomic group of expertise (Q7; S3 Table in S1 File), most respondents are entomologists (~17%), malacologists (~15%), phycologist (~10%), botanists (~10%) and mammalogists (~5%). For further analyses, we simplified this classification according to the typical main areas of research: Invertebrates (~57%, including tunicates), Botany (~22.5%, including algae, photosynthetic protozoans, and fungi), Vertebrates (~16%), and “Other” (~4.5%, including non-photosynthetic protozoans, bacteria, viruses, and those few researchers who work across two or more of the former categories). The vast majority of our respondents (Q8) work solely on extant taxa (~75%), while ~9% work solely on fossils, and ~16% work on both.

Taxonomy

In Q9, we inquired about the last 3 journals in which the respondents had published a taxonomical work. Even though we had space for three entries only, a few respondents included up to six journals; we discarded those extra entries for our analysis. Not all respondents have published more than one taxonomic paper (and seven respondents indicated that they had no publications), so we only had 1651 entries of journal titles, averaging ~2.6 journals indicated per respondent. The journals where most taxonomic works were published by our respondents were, unsurprisingly: Zootaxa (~13%), ZooKeys (~5%), and Phytotaxa (~2%) (for the other most commonly used journals, see S1 File: S4 Table).

Circa 6.5% of our respondents have published papers on all five categories of nomenclatural acts we presented (Q10), namely: synonymization of subspecies; synonymization of species; elevation of subspecies to species; demotion of species to subspecies; description of new species. Not a single respondent published on four of these categories; ~16.5% of respondents published on three categories; ~29% of respondents publish on two categories; and the remaining published on only one category. Overall, ~92% of the respondents described a new species; ~60.5% synonymized species-level taxa; ~26% synonymized subspecies-level taxa; ~31% elevated a subspecies-level taxon to species-level; ~10.5% demoted a species-level taxon to subspecies.

Following Q10, we asked the respondents about their perceived difficulty in publishing on these topics (Q11), and whether their nomenclatural acts were contested during (Q12) and/or after (Q13) peer-review. To present the results of Q11 to Q13, we excluded those respondents who had never published on the nomenclatural act of interest.

Question 11.

In Q11 (S1 File: S5 Table), the respondents assigned a value on a scale from 1 (very easy) to 5 (very difficult), regarding their perceived difficulty to publish each nomenclatural act. Overall, ~51.5% and 58.5% of respondents perceive synonymizing, respectively, subspecies- and species-level taxa as very easy or easy, while ~23.5% and ~20.5% find it neutral. Circa 61.5% and 49.5% of respondents perceive, respectively, elevating a subspecies to species and demoting a species to subspecies as very easy or easy, while ~22% and ~27.5% find it neutral. Finally, ~60% of respondents find describing new species to be easy or very easy, while ~22.5% find it neutral.

As explained above, to test whether the type of study explained the variation in scoring, we focused only on the two study categories with the most responses (describing new species and synonymizing species), given that the analysis cannot handle missing values. We retained 401 interviewees (out of 634) after filtering respondents who did not answer both questions. There was a borderline non-significant effect of type of question on scoring (LRT = 3.74, p-value = 0.05, OR = 0.74 [95% CI = 0.54–1.01]), with the odds of finding hard to publish being 26% lower for new species. In this test the interviewee identity accounted for a significant portion of the variation (LRT = 276.35, p-value < 0.01, [95% CI = 3.00–4.08]). Thus, different people have a significantly different perceptions of the difficulties of publishing, which is further explored in the second analysis.

The various questions differed in whether or not individual or study system characteristics explained the variation in responses (S1 File: S8 Table). One consistent individual characteristic was years since degree, which was a significant term in four out of five cases. Respondents further in their career consistently find it easier to publish studies than early-career researchers (Fig 1): synonymizing subspecies (χ2 = 7.76, p-value = 0.02; estimates relative to ‘11 or more’ years: ‘less than 3’ 1.33 ±0.49, ‘3 to 10’ 0.31 ±0.32); synonymizing species (χ2 = 19.79, p-value < 0.01; estimates relative to ‘11 or more’ years: ‘less than 3’ 1.09 ±0.33, ‘3 to 10’ 0.80 ±0.22); elevating subspecies (χ2 = 8.43, p-value = 0.01; estimates relative to ‘11 or more’ years: ‘less than 3’ 0.69 ±0.47, ‘3 to 10’ 0.78 ±0.29); describing new species (χ2 = 15.77, p-value < 0.01; estimates relative to ‘11 or more’ years: ‘less than 3’ 0.59 ±0.25, ‘3 to 10’ 0.69 ±0.).

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Fig 1. Responses to Q11.

Number of responses of Q11 relative to years after PhD for different types of nomenclatural acts. Colours represent the scores from 1 to 5 increasing from lightest (1 = easiest) to darkest (5 = hardest).

https://doi.org/10.1371/journal.pone.0269246.g001

Gender was significant in two cases (Fig 2A and 2E), with a lower probability of male researchers finding it hard to synonymize subspecies or to describe new species: synonymizing subspecies (χ2 = 8.34, p-value = 0.02; estimates relative to ‘female’: prefer not to say -0.76 ±0.28 male: 0.61 ±1.10), describing new species (χ2 = 8.25, p-value = 0.04; estimates relative to ‘female’: diverse 1.15 ±0.71, male -0.35 ±0.17, prefer not to say -0.18 ±0.71).

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Fig 2. Responses to Q11.

Number of responses of Q11 relative to various characteristics of the study system or respondent, for different types of nomenclatural acts. Colours represent the scores from 1 to 5 increasing from lightest (1 = easiest) to darkest (5 = hardest).

https://doi.org/10.1371/journal.pone.0269246.g002

Region was likewise significant in two cases (Fig 2B and 2D), with a lower probability of researchers in Oceania and North America finding it hard to synonymize species or to describe new species: synonymizing species (χ2 = 14.05, p-value = 0.02; estimates relative to ‘Africa’: Asia 0.06 ±0.77, Europe 0.42 ±0.69, Latin America 0.66 ±0,72, North America -0.15 ±0.70, Oceania -0.29 ±0.74), describing new species (χ2 = 16.03, p-value = 0.01; estimates relative to ‘Oceania’: Africa 0.54 ±0.66, Asia 0.21 ±0.59, Europe 0.77 ±0.61, Latin America -0.08 ±0.60, North America -0.04 ±0.63).

The academic position was significant only for elevating subspecies to species rank (Fig 2C), with the probability of finding it hard being higher for students (χ2 = 12.98, p-value = 0.02; estimates relative to ‘citizen scientist’: collection manager -1.56 ±1.02, other -1.31 ±1.03, professor -1.54 ±0.93, retired -0.83 ±1.00, student 0.08 ±1.06).

The nature of the study material was significant in one case (Fig 2F), in which the probability of finding hard to describe new species was reported lower for fossils (χ2 = 9.08, p-value = 0.01; estimates relative to ‘both’: fossil -0.12 ±0.31, recent 0.47 ±0.21).

Questions 12 and 13.

In Q12 (Fig 3A; S6 Table in S1 File), most of our respondents reported that their nomenclatural acts have never been contested during the peer-review process, either by reviewers or by editors. The nomenclatural acts were contested only ~14% of the time for synonymization of subspecies, ~18% for synonymization of species, ~14.5% for elevating subspecies to species level, ~11% for demoting species, and ~24.5% for describing new species. Most of the challenges to the acts in all categories happened in the past 5 years. The probability of having a nomenclatural act contested (yes = 1, no = 0) was significantly related to the type of the study (PBTest = 60.22, p-value <0.01), with describing new species being the most contested type (Fig 3A; S1 File: S9 Table).

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Fig 3. Responses to Q12 and Q13.

Number of responses to Q12 and Q13 relative to the different types of study/ nomenclatural acts. Yes = black, no = light grey.

https://doi.org/10.1371/journal.pone.0269246.g003

Among the other analyses on Q12, only one test resulted in a significant value (S1 File: S10 Table). The probability of synonymization of species being contested during peer-review (Fig 4A) was higher for researchers based in Africa (χ2 = 15.96, p-value = 0.01; estimates: Africa 0.29 ±0.76, Asia -1.25 ±0.46, Europe -1.34 ±0.19, Latin America -1.06 ±0.28, North America -2.03 ±0.27, Oceania -2.30 ±0.52). This, however, might be an artifact due to the small number of respondents from that continent.

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Fig 4. Responses to Q12 and Q13.

Number of responses to Q12 and Q13 relative to various characteristics of the study system or respondent, for different types of nomenclatural acts. Yes = black, no = light grey.

https://doi.org/10.1371/journal.pone.0269246.g004

The overall numbers gathered from Q13 (Fig 3B; S1 File: S7 Table), concerning contesting of nomenclatural acts after peer-review, were overall very similar to those from Q12, except for new species descriptions, which were contested only in 19% of cases. The other nomenclatural acts were contested ~16.5% of the time for synonymization of subspecies, ~18.5% for synonymization of species, ~16% for elevating subspecies to species level, and ~10.5% for demoting species. Similar to what was observed for Q12, in Q13 the probability of being contested was significantly related to the type of the study (PBTest = 46.48, p-value <0.01), with describing new species being the most contested type (Fig 3B; S9 Table in S1 File).

Among the responses to Q13, several terms were found to be significant (S1 File: S11 Table). Like in Q11, one consistent individual characteristic was years since degree, which was a significant term in three out of five cases (Fig 5). The probability of answering ‘yes’ is higher for early-career researchers for post-publication contestation of the following nomenclatural acts: synonymizing subspecies (χ2 = 7.77, p-value = 0.02; estimates: ‘less than 3’ -1.61 ±0.63, ‘3 to 10’ -3.26 ±0.72, ‘11 or more’ -1.57 ±0.22), synonymizing species (χ2 = 14.74, p-value < 0.01; estimates: ‘less than 3’ -2.83 ±0.73, ‘3 to 10’ -2.69 ±0.42, ‘11 or more’ -1.38 ±0.16), describing new species (χ2 = 10.07, p-value = 0.01; estimates: ‘less than 3’ -2.32 ±0.47, ‘3 to 10’ -1.85 ±0.25, ‘11 or more’ -1.21 ±0.14).

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Fig 5. Responses to Q12 and Q13.

Number of responses to Q12 and Q13 relative to years after PhD for different types of nomenclatural acts. Yes = black, no = light grey.

https://doi.org/10.1371/journal.pone.0269246.g005

The study taxon was significant in two cases (Fig 4C and 4D). The probability of reporting a contested nomenclatural act post-publication was lower for invertebrates regarding the demotion of species to subspecies level (χ2 = 10.67, p-value = 0.01; estimates: ‘invertebrates’ -2.81 ±0.42, ‘other’ -1.50 ±0.78, ‘plants’ -2.01 ±0.43, ‘vertebrates’ -0.92 ±0.42), and lower for describing new species for the ‘other’ category (χ2 = 10.99, p-value = 0.01; estimates: ‘invertebrates’ -1.16 ±0.26, ‘other’ -1.38 ±0.56, ‘plants’ -0.37 ±0.30, ‘vertebrates’ -0.66 ±0.34).

The nature of the study material was significant in two cases (Fig 4B and 4E). The probability of reporting contestation of nomenclatural acts post-publication was lower for researchers working on living/recent species for the following acts: synonymizing species (χ2 = 7.32, p-value = 0.03; estimates: ‘both’ -1.12 ±0.27, ‘fossil’ -1.07 ±0.33, ‘recent’ -1.83 ±0.16), and describing new species (χ2 = 11.55, p-value < 0.01; estimates relative to ‘both’: ‘fossil’ -0.13 ±0.39, ‘recent’ -0.85 ±0.27).

Finally, region is significant in one case (Fig 4F). The probability of reporting contestation of new species descriptions post-publication is higher for researchers based in Africa (χ2 = 16.12, p-value = 0.01; estimates: ‘Africa’ -0.22 ±0.67, ‘Asia’ -1.35 ±0.42, ‘Europe’ -1.22 ±0.16, ‘Latin America’ -1.20 ±0.25, ‘North America’ -2.14 ±0.24, ‘Oceania’ -1.59 ±0.37).

Gender

Around 70% of respondents identified themselves as males (Q1), demonstrating that gender balance remains at unacceptable levels in taxonomy. While it is recognized that the life sciences have a better representation of women than other areas in science and technology, that is mostly due to graduate students and postdoctoral researchers, while the gap in advanced career stages remains extreme, with only about 25% of full professors being female [23,24]. This was also reflected in our respondents: ~61% of the men acquired their highest title at least eleven years ago (Q6), while only ~41% of the women did so. Likewise, ~10% of the women were in the graduate student stage (Q5), while only ~6% of the men were in this stage.

We also identified a potential gender bias, since female researchers find it harder to publish nomenclatural acts (Q11; Fig 2A and 2E; S1 File: S8 Table). We consider this is not specific to taxonomy, but rather a more widespread problem, as gender bias in academic publishing has been recognized in other fields for a long time [e.g., 25,26].

Geography

As expected, the vast majority (~68%) of respondents work in Europe or North America (Q2; S1 File: S1 Table). While the email lists that we used to disseminate the questionnaire are international in scope, they are entirely in English, which undoubtedly decreased our reach. Nevertheless, we had a relatively large number (~16%) of respondents from Latin America (notably Brazil, ranked third in the number of respondents; S1 File: S1 Table). It is recognized that developing countries are typically the most biodiverse, but lack the taxonomists, infrastructure, and funding to accomplish the monumental task of cataloguing their wildlife [4,27].

We detected some geographical bias (Q11; Fig 2B and 2D; S1 File: S8 Table), however, in which researchers in Oceania and North America consider it much easier to get their papers published than those in other continents. The language barrier could be playing a role here, as bias against non-English speakers is a recurring problem during the peer-review process [e.g., 28]. However, we cannot exclude other possibilities and it might prove fruitful to investigate this matter further. Another potential geographical bias is that researchers based in Africa (Q12, Q13; Fig 4A and 4F; S1 File: S10 and S11 Tables) showed a higher probability of their nomenclatural acts being contested both during peer-review and after publication, including the description of new species. However, the number of respondents from that continent was low and our results could be an artifact.

Career stage

Most respondents work in universities or museums (Q3, S1 File: S2 Table: ~50% and 27%, respectively), with only circa 14% working in other research institutes. There is also a meaningful number of taxonomists working independently of academic institutions (~4%) and who do not have a degree beyond the Bachelor level (Q5, S1 File: S2 Table: ~6%). This is perhaps something particular to taxonomy, which is recognized as the only field in the biological sciences to count with significant input from “amateurs” [29,30], a fact that has been interpreted as both a boon and a curse by professional taxonomists [31]. Nevertheless, even the amateurs seem to be declining in number [20].

Over 70% of our respondents are researchers (including postdoctoral ones), professors/lecturers, or curators (Q4, S1 File: S2 Table). There is also a meaningful number (~8%) of retired professionals working in taxonomy, as expected [31]. The age bias is strong, with more than half of respondents being established/late-career researchers (Q4, Q6). Consequently, there is a dearth of graduate students (i.e., taxonomists in training) and early-career researchers working in taxonomy (Q4, S1 File: S2 Table: ~7.5% are graduate students; see also Q6: ~15% of respondents acquired their title less than three years ago), which is in line with reports in the literature signaling that the next generation of taxonomists is not being trained and that the field is slowly dying off, at least in developed countries [e.g., 6,22,32,33].

We detected a career stage bias in our responses: established/late-career researchers find it easier to publish their studies (Q11; Fig 1; S1 File: S8 Table), while early-career researchers have their published studies contested more often (Q13; Fig 5; S1 File: S11 Table). While it could be argued that this is a reflection of established researchers having more experience in publishing, the existence of a bias against early-career researchers has been reported in the literature [e.g., 34] and is also supported here by the respondents’ comments to Q14 (see below).

Taxonomy

The taxonomic group of expertise (Q7, S1 File: S3 Table) of our respondents was in all likelihood biased by the selection of email lists that allowed us to post our message. For instance, while we got a good representation of most taxonomic groups, we received very few answers from mycologists, ornithologists, and dinosaur palaeontologists. Furthermore, two of the present authors are malacologists, which might have affected the large number of respondents specializing in molluscs (ranking second overall, with ~15%).

The journals most reported by the respondents as recent outlets for their publications (Q9) were well within expectations: Zootaxa, ZooKeys, and Phytotaxa. All three journals specialize in taxonomy and are supposed to be quick outlets for publications to alleviate the publishing part of the taxonomic impediment [35,36]. Zootaxa and Phytotaxa are free of charge for their authors (though not open access), but it was somewhat surprising to have ZooKeys listed in second place, given the journal’s hefty article processing charges. Other journals relatively frequently mentioned (S1 File: S4 Table) include area-specific ones such as Phycologia, Journal of Molluscan Studies, and Journal of Mammalogy, which could be expected by the number of respondents specializing in those taxa (Q7, S1 File: S3 Table).

The vast majority of our respondents (~92%) have published new species descriptions (Q10), while only ~60.5% and ~26% have synonymized, respectively, species-level or subspecies-level taxa. While there are undoubtedly many new species awaiting description, there is also a large amount of taxonomic “clean-up” to be done. So, could these numbers be an indication that there is a bias against “negative results” (i.e., synonymization)? In this scenario, authors and editors would prioritize publishing a new species description rather than revisions (where typically taxa end up being synonymized). That could be due to a host of reasons, but it is expected that most have to do with the ‘publish or perish’ culture (curriculum, impact, institutional requirements of publications, etc.), which affects most academic disciplines and not only taxonomy [e.g., 3,37]. Describing a new species is arguably much simpler than revising a whole set of established species in terms of work and amount of data involved: access to the material (including type specimens), visits to other natural history collections (typically located abroad), imaging, laboratory work, statistical analyses, etc. Finally, in most cases, there is an added glamour to describing a new species, especially given the urgency in bringing to light unknown species vis-à-vis the ongoing Sixth Extinction [38]. Meanwhile, taxonomic revisions tend to “clean up” the taxonomy of a given group and “reduce” its apparent biodiversity due to synonymization [39]; and there is a perceived diminishing number of revisionary works [3].

But is that bias experienced or at the very least perceived by working taxonomists? Our results could be pointing towards that scenario. According to the answers to Q11 (S1 File: S5 and S8 Tables), our respondents perceive the act of describing new species to be easier than synonymizing species (borderline p-value = 0.05). Furthermore, as delineated above, established/ late-career researchers and male researchers (particularly in Oceania and North America) find it easier to publish nomenclatural acts, in particular, new species descriptions (Figs 1 and 2; S1 File: S8 Table). Facets of gender, geographic, and career-stage biases were also perceived in some of the respondents’ answers to the open-ended Q14. We explore those in full detail further below, but it is worthwhile to note one particular response, a complaint that synonymizations are more difficult to get published if the author(s) of the species in question is(are) still alive.

At the same time, new species descriptions were reported as the most challenged nomenclatural acts during peer-review and after publication (Q12, Q13; Fig 3; S1 File: S9 Table). Contesting the content of a manuscript is partly how the quality of the final publication is insured by the peer-review system [40]. If species descriptions would have been contested due to more rigor being applied and more evidence being required, we would expect that the respondents consider this nomenclatural act difficult. We, however, observed the contrary: they consider the act of describing new species easier than other nomenclatural acts. As such, contestation of new species may be happening in response to subpar descriptions (though presently we cannot judge that).

However, there is an extra layer of complexity to our results: established/ late-career researchers consider publishing new species easy (Q11; Fig 1; S1 File: S8 Table), while early-career researchers have their new species contested more often (Q13; Fig 5; S1 File: S11 Table). It is recognized by taxonomists that the field can become very prone to personal opinions that overtake scientific criteria. It is also known that biased reviews amount to a significant fraction of the system [41–43]. We hope our initial impressions of the publication practices in taxonomy will lead to more investigation of the peer-review system in the field aiming toward equity and the eradication of biases.

Respondents’ comments

The answers to our open-ended question (Q14; S1 File: S1 Fig) largely echo what is already widely recognized as the main general issues in taxonomy [7]: the unsatisfactory level of recognition the field has in academia; the lack of funding (especially in developing nations) for both research and for paying publishers’ charges (including open access fees); the difficulty in finding outlets to publish taxonomic works; and the inevitable low impact factor of those journals. Those issues are the sadly still mandatory “whining about the state of taxonomy” sensu [7]. But beyond those more immediate (and mostly external) concerns, we were also able to get glimpses of other (and internal) issues.

For instance, several respondents reported having experienced different degrees of bias and unethical behaviour in the peer-review system. The lack of accountability for reviewers (and the possibility of biased reviews) in the current peer-review system remains a major problem in academia [43–47] and taxonomy is no exception.

Some respondents also reported the difficulty for PhD candidates and early-career researchers to start a research line in taxonomy. This issue is in part linked to the peer-review problems above, but some respondents went further, singling out the issue that most taxonomists still operate as an “old-boys’ club” (direct quote), where certain older male researchers become authorities who cannot be challenged. Or, as put by one respondent: “In the fields to which I have been exposed, the ancient wise-one for a taxon still sits on all the panels/boards/chairs and stops younger/dissenting concepts getting a toe-hold. The idea of ‘peer’ is ridiculous in that context. The old guard considers themselves without peer (…).” It has been long recognized that the peer-review system has a bias against newcomers and “smaller” institutions in favour of a central elite in “top” universities [26,41], but very little has been actively done to correct this issue. Furthermore, the existence of an “ancient wise-one” in a field causes fewer papers to be published by external groups, though, in contrast, there’s a high influx of new papers and ideas soon after that person dies [48]. Given that there is a general recognition that the new generation of taxonomists is not being trained [22], this behaviour of taxonomists is a major concern, as it aggravates the issue and is counter-productive to the field. That is, the behaviour of some established/late-career taxonomists might be contributing to the collapse of taxonomy, which is a factor that has so far not been recognized among the many causes of the “taxonomic impediment”.

On a similar note, some respondents mentioned cases of “unsolicited peer-reviews” (direct quote). This refers to instances when their already peer-reviewed and published work is rejected by a committee of a given “official” checklist and thus becomes forever excluded from the mainstream handbooks and checklists. The committees, perhaps unsurprisingly, all belong to the vertebrate areas of study, with specific cases being mentioned by our respondents in herpetology, ichthyology, and ornithology. This ties in with the previous problem, given that typically such committees have biased demographics toward white male Anglophones [49].

There were also a few mentions of the problem of taxonomic vandalism, sometimes done with ill-intent and sometimes the result of the ill-advised or overzealous splitting of species due to minor and irrelevant morphological and/or genetic differences (see also [38] for a brief history of the so-called ‘mihi itch’). Malacology, in particular, was singled out by different respondents as a problematic area and fertile ground for taxonomic vandalism (see, for instance [50], for a review of a recent case). A further notable recent example comes from the field of herpetology [51]. Related to this problem, there was also mention of the lurking danger predatory and pay-to-publish journals might pose for taxonomy. Although a relatively recent phenomenon [52,53], the effects of predatory journals in taxonomy are already being felt in some areas [54].