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Referee Comments: Referee 2

Posted by PLOS_ONE_Group on 20 May 2008 at 10:12 GMT

Referee 2's review:

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N.B. These are the comments made by the referee when reviewing an earlier version of this paper. Prior to publication, the manuscript has been revised in light of these comments and to address other editorial requirements.
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This is a potentially interesting analysis of the timing of diversification in selected groups that are hypothesized to have undergone rapid radiations in Macaronesia. The results expand upon previously published phylogenetic data by analyzing the results in a temporal context and comparing timing of colonization and diversification across the selected lineages. reported have not been published elsewhere.

My main concerns lie with the rigor of the material and methods and the presentation of the results and discussion. The text is well written, but misses several key issues pertinent to island biogeography. Also there is some concern with clear statement of goals for the project and hypotheses to be tested. The groups were selected because they were thought to have undergone rapid radiations, and that could skew the results to finding ages that are consistent for radiations rather than actual timing of dispersal/colonization of the Macaronesian islands.

More details about building phylogenies (are all known species sampled, what is the purpose of having nearest continental species and outgroups (how do they differ from one another), how well did the data fit the clock models). There is no reference to the supplemental figures in the text, yet these figures are essential to interpretation of the author's results. Even with the supplemental figures, the use of codes for generic and species names makes it impossible to interpret the phylogenetic and chronographic findings. These supplemental figures are integral to the paper and should be revised and included, meanwhile the composite figure of the phylogenies should be removed as it provides no additional useful information - no branch support values, no taxonomic names (just codes that are difficult/impossible to interpret), no relationships of the pictures to any of the clades, and branch lengths that are not related to time. Figures presented should be chronograms (branch lengths = time), they should have terminal taxa named, and it should be made clear in the text if each analysis includes all known taxa that inhabit the island. Missing taxa would greatly effect the results of these analyses.

I've made additional comments on the MS. I have concerns about the formula used to determine average rates of diversification in light of the availability of algorithms that would be more appropriate to take into account some of the phylogenetic and branch-length variability in the data.