Responsiveness to cold snaps by turtle embryos depends on exposure timing and duration
Data files
May 23, 2024 version files 32.42 KB
Abstract
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.
README: 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.
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