DOI: 10.5061/dryad.37pvmcvt9
title: Responsiveness to cold snaps by turtle embryos depends on exposure timing and duration

description: Characterizing how organisms respond to transient temperatures may further
 our understanding of their susceptibility to climate change. Past studies
 in the freshwater turtle, Trachemys scripta, have demonstrated that the
 timing and duration of heat waves can have major implications for the
 response of genes involved in gonadal development and the production of
 female hatchlings. Yet, no study has considered how the response of these
 genes to transient cold snap exposure may affect gonadal development and
 the production of males. We investigated how cold snap timing affects
 gonadal gene expression in T. scripta embryos and how the duration of an
 early cold snap influences resulting hatchling sex ratios. Results show
 that responsiveness to cold changes rapidly across development, such that
 genes that responded when exposure began on incubation day 14 responded
 differently when exposure occurred just 4 or 8 days later. Sex ratio data
 revealed that embryos experiencing an early cold snap also require a long
 exposure (20 days) before most commit to testis development, suggesting
 warm baseline temperatures may lower their sensitivity to later cold snap
 exposures. These results highlight how individual responses to incubation
 temperature can change rapidly across development in turtles and have
 important effects on sex ratios.
description: # Responsiveness to cold snaps by turtle embryos depends on exposure
 timing and duration ## Description of the Data and file structure The
 Excel data file has two sheets corresponding to each of the two
 experiments conducted. The first sheet contains gene expression values of
 multiple genes as obtained from biological (embryonic gonads) samples in
 experiment #1. The second sheet contains sex ratio data collected from
 experiment #2. Each sheet also contains information on the treatment and
 sampling point of each individual analyzed. Sheet
 "Gene_Expression_Data" headers: * Sample Name: an arbitrary but
 unique number assigned randomly to the collected tissue samples (not used
 in data analysis) * Egg ID: identifies individual T. scripta eggs (i.e.,
 embryos) used in study * Trt: the treatment applied to that egg; indicates
 whether an individual was swapped to cold snap conditions on incubation
 day 14, 18, or 22 * Sampling Point: indicates when (per treatment) that an
 egg was sampled; each treatment had a total of 7 sampling points
 corresponding to 0, 3, 6, 9, 12, 15, or 18 days of exposure *
 days_of_exposure: like the sampling point, this indicates the number of
 days spent under cold snap conditions prior to sampling (0, 3, 6, 9, 12,
 15, or 18 days of exposure) * Gapdh CT Mean: mean expression (CT) for the
 house keeping gene * NDmrt1: normalized expression of Dmrt1 gene (using
 2-ΔΔCT method relative to Gapdh) * NCyp19A1: normalized expression of
 Cyp19A1 gene (using 2-ΔΔCT method relative to Gapdh) * NKdm6b: normalized
 expression of Kdm6b(+IR) gene (using 2-ΔΔCT method relative to Gapdh)
 Sheet "Sex_Ratio_Data" headers: * Egg: identifies the egg number
 of sampled embryo * Treatment: shows duration of cold snap treatment
 applied (0, 3, 6, 9, 12, 15, 18, 21, or 24 days long) * Sex: shows the
 determined sex of the individual (M = Male, F = Female) * Successes_F:
 gives the value of 0 or 1 if sample was male or female, respectively *
 Failures_F: gives the value of 1 or 0 if the sample was male or female,
 respectively * Proportion_F: shows the determined proportion of females
 within that particular treatment * Successes_M: gives the value of 1 or 0
 if the sample was male or female, respectively (same as Failures_F) *
 Proportion_M: shows the determined proportion of males within that
 particualr treatment The included R script code shows how we analyzed our
 gene expression data (experiment 1), including how assumptions of GLMs
 were checked, and how post-hoc comparisons were carried out and adjusted.
 ## Sharing/access Information NA