Peer review is a critical factor in promoting the rigor and high quality of scientific research. The entire scientific community benefits when the peer-review process is timely, thorough, and balanced. The editors of Frontiers in Biology greatly appreciate the tremendous collective contribution that reviewers make to our journal and the articles they publish. We hope that the guidelines described below will help facilitate peer review as a conversation between authors and reviewers, and as an essential element of the publication process. 

Reviewer invitations for Frontiers in Biology are sent out by email from the Editorial Office (zhangxl@hep.com.cn) or the online submission & peer review site (http://mc.manuscriptcentral.com/fib). The invitation includes information about the title and abstract of the manuscript and an indication of the time frame (TWO WEEKS) in which we would like to receive the review. After agreeing to review the paper, the reviewer has access to the entire manuscript. We encourage reviewers to contact the editorial office at any time if they require additional information or assistance. 

The content of the review 

The core of any review is an objective assessment of both the technical rigor and the novelty of the presented work. Key features of a review include (1) an outline of the conceptual advance over previously published work, (2) a specific recommendation, (3) the reasons for that recommendation, and (4) a summary of the specific strengths and weaknesses of the paper. Specific comments regarding the weaknesses of the manuscript and suggestions for improvements are important components of an effective review.In this regard, we encourage referees to comment on the quality and presentation of the figures as well as the validity of the statistical methods used to interpret them. (If necessary, the editors can obtain primary data from the authors for referees' use in these more detailed evaluations.)
Some other issues that are often useful to discuss include (1) alternative hypotheses that are consistent with the available data, (2) the paper's potential audience (i.e., the relevant fields within the readership of the journal), and (3) balanced referencing of the pre-existing literature. In particular, when previously published work has undercut the novelty of the present findings, it is extremely helpful to include in the body of the review detailed citation of the relevant articles and data. 

Comments to the editors 

If some specific aspects of the report seem inappropriate for presentation to the authors, they can be sent as comments for the editors' eyes only. However, all general concerns that impact the reviewer's overall recommendation should be indicated clearly in the comments to the author as well, not just in the comments to the editor. This includes but is not limited to concerns about the level of conceptual advance or significance. In general, the tone of the comments to the authors should be consistent with the tone of the comments to the editors. From the authors' point of view, the final editorial decision should be a direct reflection of the reviewer comments that they receive.
A more general context in which comments to the editor can aid the editorial process is as an executive summary of the comments to the authors. In addition, this is an appropriate place to discuss any suspicions of ethical violations-either in the research itself or in the manner in which it is presented. Such issues might include suspected data manipulation or fraud, plagiarism, duplicate publications, or unethical treatment of animals or research subjects.
Reviews can and should be critical, but we ask reviewers to keep in mind that dismissive language and personalized criticisms may be viewed as reflecting bias or ulterior motives on the part of the referee.
A timely and efficient review process benefits the entire scientific community and is therefore a key editorial goal of Frontiers in Biology. In most cases, Frontiers in Biology considers 14 days to be sufficient time to review a manuscript. However, we do appreciate that reviewers juggle a number of priorities. If a referee is willing to review the paper but would require more than 14 days to do so, we ask that he/she contacts the editorial office. It is important to inform the editor when a review is likely to be late; a revised estimate of the time until submission of the review and an explanation for the unexpected delay are invariably helpful.

It is important to preserve the objectivity of peer review and public confidence in its rigor and impartiality. For this reason, we ask reviewers to be sensitive to the potential for conflicts of interest, both real and perceived. If any potential impediment to objectivity may exist, reviewers should either decline to review the paper or, in cases when they are uncertain, contact the editor for advice. It is certainly worth considering these issues if a manuscript (1) originates from an author who has recently had close personal interactions (of a strongly positive or negative nature) with the reviewer, (2) is identical to some subset of the reviewer's currently active research program, or (3) impacts a topic in which the reviewer has a financial interest. For example, if the reviewer is collaborating with one of the authors or is preparing to publish a paper that comes to conclusions that overlap those of the manuscript in question, he/she should decline to review it. 

Reviewers must preserve the confidentiality of unpublished work. Any manuscript or abstract sent for peer review is a confidential document and remains so until it is formally published. In some instances, reviewers may feel that it would be helpful to obtain additional advice from a colleague. In such cases, we ask that the reviewer contact the editor in advance to ensure that the editor has the opportunity to take additional information into account before permitting communications that have the potential to violate confidentiality. It is not appropriate to discuss unpublished manuscripts at laboratory meetings or journal clubs. Reviewers can collaborate with trainees (graduate students and post-docs) in the evaluation of manuscripts, and we appreciate that such collaboration functions as an important training exercise. However, we ask that reviewers keep the number of collaborators to a minimum and include the identities of all the individuals involved in the "comments to the editors" component of their review. Regardless, the person originally invited to review the manuscript is ultimately responsible for maintaining confidentiality and for the content and accuracy of the report. We encourage referees to inform collaborating reviewers about appropriate guidelines and ethics for peer review, as outlined in this document. 

Frontiers in Biology will not disclose any reviewer's identity except at the specific reviewer's request. The editorial offices will not confirm or deny any author queries related to reviewer identity; reviewers are encouraged to adopt a similar policy and to refrain from discussing with the authors any manuscript under active consideration. If an author contacts a reviewer, that reviewer should feel free to notify the editor. 

Reviewing (or re-reviewing) revised manuscripts 

For the sake of editorial consistency and fairness to the authors, we request that referees who agree to review one version of a given manuscript also commit to reviewing future revisions if necessary. In an effort to minimize the resulting burden, we make every effort to handle revisions editorially and to curtail unproductive resubmission cycles.