Endemic Sicilian Brown Trout Endangered by Hatchery Introgression and Low Gene Diversity^†

Round 1

Reviewer 1 Report

Dear authors

I made some suggestions on spelling and grammar, please check and replace the XXXX. It would stay like this.

Brown trout (Salmo trutta) populations living in Mediterranean peninsulas and surrounding islands belong to old evolutionary lineages that persisted during Quaternary glaciations. Many of these populations inhabit marginal areas along the south limit of the distribution of the species, where they face hard environmental conditions (drought, high temperatures and sudden shifts in water flow) that can get worse by anthropogenic activities and climate change. In islands, this vulnerable situation is exacerbated by geographical isolation. Sicilian trouts remain only in the south-eastern part of the island and, based on its morphological characteristics, it has been recognized as a distinct species named Salmo cetti. Despite its genetic singularity among other Italian trout — it is the unique Italian native trout of Atlantic origin — mitochondrial DNA haplotypes described in Sicily clearly relates this species with brown trout Atlantic lineages from North-Africa and the Iberian Peninsula. In the present study, brown trouts from four rivers of north-eastern Sicily were genetically analysed. Based on genotyping of the mitochondrial (XXXX) and nuclear (XXXX) genes this study aimed to: evaluate the impact of past stocking practices in natural populations, estimate mitochondrial and nuclear gene diversity and reconstruct the phylogenetic relationships of Sicilian trout. First results showed that only trouts from Tellessimo River keeps free from hatchery introgression. Gene diversity was low in most populations, and both mitochondrial and nuclear phylogenetic reconstructions related Sicilian trout with old Atlantic lineages.

Sincerely yours

Joana

Author Response

Dear editor

All grammar changes suggested have been made.

Thank you to the reviewer for improving our abstract.

We have attached the new version of the manuscript

Sincerely

Nuria Sanz

Author Response File: Author Response.docx