Review for "The queenslandensis and the type form of the dengue fever mosquito (Aedes aegypti L.) are genomically indistinguishable"

Completed on 29 Sep 2016

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This manuscript investigates to what extent worldwide disseminated domestic Ae. aegypti specimens morphologically identified as the pale variety queenslandensis and the type form from Australia and Singapore are reproductively isolated ("how freely they interbreed"). A total of 74 sympatric pale and type Ae. aegypti were genotyped for a 1170 bp-long mitochondrial sequence and 16,569 nuclear SNPs.

Although I am not an expert on Aedes taxonomy, I have identified a few issues that should be better explained/corrected before this manuscript is considered as publishable material.

1. Published references are cited in a very loose manner. Sometimes even with disregard to their original meaning (i.e. Powell & Tabachnick 2013).

While we appreciate reviewer’s critical assessment of our work, we cannot agree with this conclusion and are not able to address it without a concrete example of what is being disregarded.

Our citation of the e.g. Powell & Tabachnick paper (2013) refers to their statement regarding McClelland’s 1967 conclusion that the classical subdivision within Aedes aegypti is a gross oversimplification and that “...Aedes aegypti cannot be split into definite interspecific entities...” Powell & Tabachnick (2013) conclude on page 16, paragraph 1: “...In the 45 years since, this advice has often been ignored, even in recent times”.

Our reference (underlined) to Powell & Tabachnick conclusion (above) states:

...“McClelland [7] suggested that subdivision into forms seems oversimplistic and should be abandoned unless correlation between genetic and color variation can be demonstrated [7]. His recommendations have been largely disregarded [9]) despite the fact that multiple genetic marker systems (allozymes, microsatellites, nuclear and mitochondrial SNPs) have failed to find a clear differentiation between forms and markers [10][11][12].” (page 4, line 82-87).

We have now changed this sentence to: “In their latest review of Ae. aegypti history, Powell and Tabachnick [9] point out that McClelland’s recommendations have often been ignored for the past 45 years...”, to further clarify the context for this citation (line 88-89).

2. Chan et al (2014) did not consider Ae. aegypti aegypti and Ae. aegypti queenslandensis as separate entities.

This is correct and we did not attempt to argue that Chan et al. (2014) considered them as separate entities. We said that their finding of a relatively high mitochondrial divergence between the two forms “..., although lower than a commonly adopted threshold of 3% for species delineation in insects [14], suggests that the two forms may not freely interbreed. ” (line 94-97). Hence, we decided to further test this hypothesis.

3. No significant differences in oral infection of DENV-2 between pale (Ae. aegypti queenslandensis) and dark (Ae. aegypti aegypti) were ever observed (Wasinpiyamongkol et al. 2003).

That is correct, but nowhere in the text do we argue to the contrary. In fact, the findings of Wasinpiyamongkol et al. (2003) further support our conclusions and we have now included this citation (line 268-269).

4. The taxonomy of the variation seen within Ae. aegypti, as presented, is flawed and incomplete.

It is little hard to respond to this. Our work was not intended to present a taxonomic description of phenotypic variation, and we followed the well-established color/scalling criteria of Mattingly and McClelland (described in the text). The focus of our work was to test if the two forms are genetically distinct using the mtDNA and nuclear SNP variation.

I feel that the scientific issue selected to be addressed has not been properly defined or characterized.