Genomic analysis of saline-tolerant Nile tilapia strain shows signatures of selection and introgression from blue tilapia (Oreochromis aureus)

Tilapia are a group of originally freshwater species, some of which can be cultured in a wide range of salinities, e.g. in estuaries or in brackish water ponds in polyculture with shrimp. Although the physiological characteristics for osmoregulation have been studied extensively, it is less clear how selection results in adaptation to salinity stress. Here we studied the genomic architecture of one saline-tolerant strain, called “Sukamandi”, which was selected to grow well in brackish water. We also investigated the impact of selection for salinity tolerance on the genome. Since the Sukamandi strain is assumed to be derived from Nile tilapia (Orechromis niloticus) and blue tilapia (Orechromis aureus), we also searched for introgression signatures to understand their influence on salinity tolerance.