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Dear Barbara,
Thanks for the changes. I regard the ms as acceptable.
Best wishes
Mike
[# PeerJ Staff Note - this decision was reviewed and approved by Gerard Lazo, a PeerJ Section Editor covering this Section #]
Dear Barbara,
I have received a review on your revised version of the manuscript on Capsella. The reviewer is quite positive about the changes you've made. She/he asked to specify your material and methods in more detail. Besides are only a few things to change.
Therefore I follow the recommendation of the reviewer and assign minor revisions to your manuscript.
With best wishes
Mike
The revised manuscript is now organized more clearly, and focuses on some well-defined aspects. Briefly, differences in assimilation and stomatal density of the two ecotypes are now addressed and reported, considering different light regimes. In this form, the manuscript is suitable for a Short Communication.
Information should be added how many leaves were used for the gas exchange measurements. Obviously, one individual was used for each type. These information should be clearly stated in the manuscript, because it is not obvious from Supplementary Table S2, which represents the output of the gas analyzer.
L. 142: In their response letter (but not in the text), authors explain that stomatal conductance is expressed as fraction of fully opened stomata (0.2 would then mean 20 %). However, there are still no absolute values provided. In Suppl. Fig. 1, stomatal conductance (as fraction) varies between 0.1 and 0.35 (roughly). It is totally unclear, what the reference for the the fraction values is. Usually, in gas exchange studies, total absolute values are provided.
No comment.
There are some comments left:
Abstract:
“Even under limiting CO2 concentrations….“ I would suggest: “Even under ambient and subambient CO2 concentrations….“
“Any disadvantage due to less…“ This and the following sentence are quite unclear. I recommend to overhaul this last part oft he abstract to provide a concise summary of the basic results.
L. 49: Maybe, “flower structure“ would be a better term?
Ls. 61-63: Which type was preferred by pollinators?
Dear authors,
I have received 2 reviews, with recommendations for major revisions and resubmission. Reviewer 1 suggests to further analyse your data, in particular to extend the data analysis towards more physiological aspects. Reviewer 2 also suggests to look at other traits, and to give a much deeper justification on your aims and methods. The frame of your approach should be widened. Reviewer 2 also argues for a better and more consistent structure of your text parts, including introduction material and methods, and the discussion.
Based on these reviews I ask for major revisions, which means in this case a full revision of your manuscript.
Please address the points made by the reviewers. I will send out your resubmission for review again.
With best wishes
Mike Thiv
No comment
No comment
No comment
The study deals with trait differences between two ecotypes of Capsella bursa-pastoris which are linked to gas exchange and photosynthesis. In short, both ecotypes were found to differ with respect to stomatal density and assimilation rates, particularly under high-light conditions. Although the contribution represents a quite short manuscript, the topic of physiology-related anatomical differences of different ecotypes should be of interest to many readers. However, the data analysis falls short of essential steps to evaluate gas exchange and assimilation parameters (currently, the manuscript looks more like a descriptive report). There are quite a few more things that can be done with the data, and which would make the contribution much more attractive.
From the available A/Ci curves, it should be possible to calculate key parameters, particularly Vcmax and gs against Ci (or Ca). Particularly, it would be relevant to determine the limitation of assimilation by stomatal conductance gs. It would also be possible to estimate gs max differences between both ecotypes on the basis of the microscope images (for example, using the equation of Parlange and Waggoner, 1970, Plant Physiology) and to compare the result with the measured gs. With respect to plant performance in the natural habitat: are there significant differences which can be derived from the lab results?
Furthermore, the Discussion section starts with discussing leaf type differences between C. bursa-pastoris ecotypes, on more than one page, until it is stated that “…we neglected the character leaf type in our experiment.” Why do the authors discuss leaf type when it was not considered here?
Some specific comments are listed below.
Specific comments
Line 81: “…indicating that overall evolutionary fitness remains unaffected…” Only the fitness-related factor “seed production” appears to be unaffected. Additionally, “evolutionary fitness” sounds awkward.
Line 145: “…a conductance of at least 0.2 was maintained…” Please provide units.
Lines 226 – 228: “The ecotypic adaptation of the leaf to various habitats and conditions at geographically and climatically different places of origin of many populations became obvious.“ What does this sentence mean?
Lines 242 – 244: “The physiological advantage is accompanied by higher stomata density on the upper and lower epidermis. It seems that the higher photosynthetic capacity is gained by a higher number of stomata per area. Physiological differences between high-light and low-light conditions might be the consequence of anatomical improvement,…” These assumptions may be supported by the data analysis suggested above.
Figure 4 and Table 1, and Supplement: “Stomata above” and “Stomata below”: Unusual description: should be substituted by adaxial/abaxial.
PEERJ 38123: Stable intraspecific sympatry between weed ecotypes in a single habitat
The objective of this work was studied the ecotypic differentiation of the rosette leaf using anatomical and physiological methods in C. bursa-pastoris (wild type) y C. apetala (Spe-mutant). At that point I recommended rejection due to the lack of sufficient depth and novelty in the manuscript, but I recommended resubmission with new data and/or rewritten. There are many aspects of the methodology that are difficult to interpret and thus need to be clarified. I include the most important doubts in that follows.
The major fails of the manuscript are in the next section.
Another minor comments
- The title is not very informative about the content of this work. I suggest rewrite
Line 93. Where the plant accumulate assimilates? In the same leaves or in storage organs as reserves?
line 94. The relationship between accumulation and yield need a citation.
What is plant habitus? Life form is a better term…. .
Line 152-155. All this paragraph is method… it did not report any result. How authors measured plant habitus?
Lines 170-174. All this paragraph is method….
Plant Material: For the analysis of both ecotypes, authors used a bulk seed of two populations?
the verb tenses of the results are incorrect
Line 181. What is “plants were grown in LL” LL never was defined.
Your introduction needs more detail, about the leaf trait that authors measured and why (justification of this work). It has a larger description of flower type and pollinators, fecundation, etc. only to support the idea that the population of both ecotypes C. bursa-pastoris and C. apetala have a lot of barriers limiting their crossing. I suggest reduce this information, because it is not relevant for the study of rosette leaves. However, nothing is explained about the importance of leaf traits for ecotypic differentiation, and specifically why the traits that authors choice (stomatal density and photosynthesis only).
The objective need to be better stablished, including some hypothesis about why authors expect differentiation in the rosette leaves between ecotypes. If populations are sympatric, and the leaf function is mainly (as described) photosynthesis, accumulation, and protection; Why authors expected that the rosette leaves differ? Also, in materials and methods, authors say that divided plants in two treatments: (i) high-light setting (600 μmol quanta m-2s-1); (ii) low-light setting (100 μmol quanta m-2s-1). Why? Which is the objective of the light treatment? In the result section authors report floral induction…. But neither in materials and methods nor in introduction mention this point.
Traits: Authors measured morphological and physiological traits such as: stomata density, photosynthesis rate and Ai vs Ci curves. I consider that there are many others leaf traits that provide important eco-physiological information like Specific leaf area, leaf thickness, leaf size, and are related to resource use strategy. To include some of these traits could greatly enhance the manuscript. I consider that there are not many traits to make a complete characterization of ecotypic leaf differentiation.
There is not a section of statistical analysis in materials and methods section. Why use a non-parametric analysis? The difference in stomatal density should be analyzed with a two-factor analysis: Light intensity and ecotype. I cannot understand the information showed in Table 1: it is incomplete? What is the number shown? What is compared? Differences between ecotypes or light intensities? Is there interaction?
Authors need to explain how to analyze the curve Ai vs ci. In the result sections describe a lot of parameters that is impossible to see in the figure.
I consider that the discussion section is not focused on the objective of the manuscript. It describes a lot of genes or loci responsible of the leaf type determination, while the objective of this work is a morphological and physiological characterization. If there are four leaf type possible… it would be described in the introduction. Which are these?
I can not to put in context the discussion about the differences in the responses of the ecotypes to the light environments because I do not understand the objective of this treatment. It is not clear along all the manuscript.
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