Planarians, a Neglected Component of Biodiversity in Groundwaters

Round 1

Reviewer 1 Report

In my first review I recommended rejection basing on the lack of important new findings in the present work, most of their conclusions are already present in the introduction. Moreover, I detected a lack of order in the exposition of facts along the ms that I explained in my review as well as some of the main failures for the paper to be acceptable. I see than nonetheless the authors have taken my comments as a possibility to make the ms better and resubmitted. I’m sorry to say that, although the effort to give a better organized content has been good, I still find that the information contributed is not relevant enough to be published in this journal, and some parts are still messy. For instance, as I already stated I do not see that their analyses on the functional role of planarians give answer to any relevant question, I also have my doubts on the validity of the analyses done given the amount of data and their fragmentation.

Author Response

We are glad that the reviewer appreciated the improved organisation of the text that he found now good. Following the comment we improved discussion section and we state possible limitations of the analyses.

We should remark, however, that while reviews are routinely performed in scientific studies to understand the current state of knowledge and provide future research perspectives in a given field, few perform a standardised research as ours. We remark to the reviewer that covering the whole spectrum of literature is almost impossible, especially in traditional disciplines that have a long history and a large amount of what has been improperly called “grey literature.” Without a specific and easily repeatable method, such a comprehensive review may lead to biased conclusions. And our procedure is exactly what it wants to gather.

To avoid bias, many scientific fields haveas a matter of fact started to favour the use of systematic evidence reviews (Acreman et al. 2020) as the one that we performed for this paper. We therefore performed a systematic review to find focused data that addressed our three aims. In particular, we remark that for this review, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (Page and Moher 2017).

Reviewer 2 Report

Dear authors,

the manuscript has improved considerably since the first submission. Now it is better readable and some of the issues that arose have been solved properly. I still have my concerns about the methods used for the screening of the literature, but I consider that the way that has been rewritten is much understandable. For that reason, I consider that the article can be published.

Author Response

We are grateful for the positive comments and for the suggestions that improved manuscript quality.

Reviewer 3 Report

The authors have satisfactorily addressed the reviewer comments.

Author Response

We are grateful for the positive comments and for the suggestions that improved manuscript quality.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The paper by Barzaghi et al does a systematic review of literature to find out the situation of the study of groundwaters planarians in level of interest raised and knowledge about their ecology (situation in food web and adoptation of troglomorphic features). Although the idea seems atractive I find the paper does not fullfils the objectives posed.

In the first place the authors propose at the beginning 4 questions, that I think are finally not satisfactorily answered. For instance I can not see answered question 3 (researchers on groundwater-dwelling planarians vary according with the typology of the study ?).

The last question, about trophic functional role of planarians, is neither answered, the information they seem to retrieve from the literature reviewed is not different from what they seemed to know before hand (as I can guess from the similar explanations in the introduction and the discussion section about this issue). The authors explain that they have searched other literature for the presence of non-planarian organisms (either putative predators or prey for planarians in the sites described in the planarian papers), I expected to find some graphics on this but in the discussion they seem to talk only about the sympatry reported on the papers dealing on planarians. They also perform some analysis on correlations, but then they recognize in the discussion that may have not selected correctly the data on other species. Why didn’t they repeat the analyses to see whether their perception of the possible reason for the anomalous results was right? Why didn’t they present directly the analysis with a correct selection of other-organisms?

 

Also, referring to the troglomorphic features, which seems to me the more interesting point for the information they have put together, figure 3 A and B are identical, this was for sure a mistake in the preparation of the figure.

 

Moreover, the authors limited their study to the English written papers, which left out of the survey important information from broad world areas. I understand that there are obvious reasons, as some must not be easy to find because they may not be online, but they recognize some are. I understand the difficulty to read them in their vernacular languages, but nowadays there are very good automatic translation tools that may have allowed to include some more articles and widen the geographical information on the presence of planarians in cave habitats and on the authors working on them.

 

Other questions are:

At some points the writing and especially the organization of the manuscript is poor. For instance, the discussion could have been subdivided with titles in function of the 4 questions to be treated. Also repetitions from what had already been explained in the introduction could be avoided.

I do not fully understand why the first search terms are «planarian cave » and « flatworm cave » and in the case of GS only the second is used.

It is neither clear for me how did they decide on the typology of the papers. Moreover, I will have expected some of the papers to be included in more than one of these categories, but it does not seem to be the case.

Reviewer 2 Report

Dear authors,

 

the manuscript entitled "Planarians, a neglected component of biodiversity in groundwaters" is an attempt to present the overview of the available literature that includes groundwater planarians. It is a good idea, and I totally agree with the authors that a revision is necessary. However, the approach is not entirely correct in my opinion. Only including articles written in English in the analysis eliminates a very important part of the literature on these animals. Above all, the old papers on planarians are written in other languages, such as French, Portuguese, Spanish, German, Italian, Japanese, or Russian. Not taking these articles into account bias the results of the analysis, leading to surely erroneous conclusions, about a lack of literature dedicated to the subject. Also, the filtering method used may be too restrictive, reducing the dataset to only 48 articles.

 

In general, the manuscript should be revised, both for the writing and the language, which need to be improved considerably. There are many typos that have to be checked.

 

The figures are adequate but could also be improved. The legend of figure 1 does not explain well what it refers to. Figure 3 could be more self-explanatory and perhaps include some images.

 

Some more specific comments are in the attached document.

Comments for author File: Comments.pdf

Reviewer 3 Report

Barzaghi et al. perform an extensive literature review for papers reporting identification and description of planarian species inhabiting groundwater-dwellings. Very little is know about cave planarians. The well-executed literature analysis makes a sound contribution that will serve as a springboard for future research on cave planarians' biology. I believe this article is suitable for publication in Diversity. I only have minor editorial comments the authors could consider. 1) The authors have been cautious, qualifying the absence of information on planarians by generally referring to groundwater-dwellings or cave habitats. The last sentence of the Abstract and the main text occasionally state, "low attention has been dedicated to planarians," which is a little misleading given that attention (and research funding) is being given to freshwater planarians. It could be worthwhile to delineate the contrast as it is entirely accurate. There is little to no information in the literature about cave planarians at the molecular level. 2) Line 216: There is "t" that should be deleted. 3) Line 264: Should be "night from the day" (not "form").