DOI: 10.5061/dryad.63xsj3v03
title: Choice consequences: salinity preferences and hatchling survival in the mangrove rivulus fish (Kryptolebias marmoratus)

description: In heterogeneous environments, mobile species should occupy habitats in
 which their fitness is maximized. Mangrove rivulus fish inhabit mangrove
 ecosystems where salinities range from 0 to 65 ppt, but are most often
 collected at ∼25 ppt. We examined the salinity preference of mangrove
 rivulus in a lateral salinity gradient, in the absence of predators and
 competitors. Fish could swim freely for 8 h throughout the gradient with
 chambers containing salinities ranging from 5 to 45 ppt (or 25 ppt
 throughout, control). We defined preference as the salinity in which the
 fish spent most of their time, and also measured preference strength,
 latency to begin exploring the arena, and number of transitions between
 chambers. To determine whether these traits were repeatable, each fish
 experienced three trials. Mangrove rivulus spent a greater proportion of
 time in salinities lower (5–15 ppt) than they occupy in the wild.
 Significant among-individual variation in the (multivariate) behavioral
 phenotype emerged when animals experienced the gradient, indicating strong
 potential for selection to drive behavioral evolution in areas with
 diverse salinity microhabitats.We also showed that mangrove rivulus had a
 significantly greater probability of laying eggs in low salinities
 compared with in control or high salinities. Eggs laid in lower salinities
 also had higher hatching success compared with those laid in higher
 salinities. Thus, although mangrove rivulus can tolerate a wide range of
 salinities, they prefer low salinities. These results raise questions
 about factors that prevent mangrove rivulus from occupying lower
 salinities in the wild, whether higher salinities impose energetic costs,
 and whether fitness changes as a function of salinity.
description: For the salinity preference in a lateral gradient experiment time
 spent in each salinity chamber was obtained using JWatcher and then
 combined into one data sheet. Then in R the time spent per chamber was
 converted to an average preference score and we then calculated the
 variance of each fish's preference and this is defined as the
 strength of preference. Data for the egg laying
 preference experiment was manually entered into excel at the time of each
 egg check. Eggs were then checked daily for hatching and as eggs hatched
 this data was also entered in manually to an excel file. 
description: Each sheet of the excel workbook represents a set of data that
 was used in the analysis. In each sheet, treatment is
 identified by E = experimental or C = control. The data
 for the salinity preference in a lateral gradient experiment can be found
 in the sheets "sal_pref_time" and
 "sal_pref_scores".  The sheet entitled
 "sal_pref_time" includes the amount of time (in seconds) spent
 in each salinity chamber. If the fish was in the experimental treatment (E
 in the "treatment" column) then a 1 in the "salinity"
 column equals 5 ppt, 2 equals 15 ppt, 3 equals 25 ppt, 4 equals 35 ppt,
 and 5 equals 45 ppt. If the fish was in the control treatment (C in
 "treatment" column) then the numbers in the "salinity"
 column identify the chamber that the fish was in. The latency to emerge
 time is in the "emerge_s" column; this is the amount of time (in
 seconds) that the fish took to leave the central compartment at the start
 of the trial for each round.  The
 "sal_pref_scores" sheet includes the converted preference score
 (see methods section of manuscript for details) for each fish, the
 strength of preference, along with the total number of transitions made
 between chambers, and the latency to emerge from the central chamber at
 the start of the trial for each round.  The data for
 the egg laying preference experiment are located in the
 "eggs_laid" and "eggs_hatched" sheets.
 In the "eggs_laid" sheet the "time" column
 refers to the egg collection at the end of the first week (1) or at the
 end of the second week (2) in the gradient. "Salinity"
 identifies which salinity chamber (or just which chamber for the control
 treatment) the egg was located in, as in the "sal_pref_time"
 sheet; the salinity codes are the same (1 = 5 ppt, 5 = 45 ppt). If at
 least one egg was located in the salinity chamber then a 1 was entered in
 to the "eggs" column, if no eggs were found then a 0 was
 entered. We also included if the chamber was an "edge", chambers
 1 and 5 are located at the end of the of the gradient and each received a
 1 in this column, while chambers in the middle 2-4 each received a
 0. The "eggs_hatched" sheet includes whether
 or not an egg hatched, 1 = hatched and 0 = did not hatch.