Poecilia reticulata competition and salinity study

The aim of this study was to understand how salinity and the presence of competitors alters gene expression in the brain and gill tissue of Poecilia reticulata. Following a 2x2 design, we sequenced the transcriptome of adult (12 or more weeks old) male P. reticulata after 24hrs in either brackish water (15psu) or freshwater (0psu) and in the presence of either a single adult male Poecilia picta or a single adult male Poecilia reticulata. Prior to this study, all study fish were alone in freshwater for 48hrs. All subjects were the lab born grand offspring of Poecilia reticulata taken from the island of Trinidad in the Spring of 2016 or summer of 2017 from a population located at 10.61925, -61.42649. Prior to this study, the grandparents, parents, and study fish were housed in group tanks (2-6 fish per tank) in a lab facility at Colorado State University in freshwater on a 12hr light cycle under temperature conditions that mimicked Trinidad (25 plus or minus 1C) and fed tropical fish food daily at an amount that achieved 85-90 percent maximum growth rate (Reznick Am. Nat. 120 (1982)). All study fish in this study were virgin males. Tissue was extraction was conducted after a rapid decapitation between 10AM and 11AM. Tissues were then stored in RNALater (Invitrogen by Thermo Fisher Scientific) until RNA extraction was conducted using Qiagen RNeasy Mini Kits. Messenger RNA libraries were prepared and sequenced at the University of Texas at Austins Genetic Sequencing and Analysis Facility. 100bp single end sequencing was done via TagSeq protocol using an Illumina NovaSeq 6000 platform.