Short heatwaves during fluctuating incubation regimes produce females under temperature-dependent sex determination with implications for sex ratios in nature

• Published in: Scientific reports Vol. 8; no. 1; p. 3
• Main Authors: Carter, A. W., Sadd, B. M., Tuberville, T. D., Paitz, R. T., Bowden, R. M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08-01-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 60 APPLIED LIFE SCIENCES; 631/158/2455; 631/158/857; Animals; Embryos; Empirical Research; Female; Heat waves; Hot Temperature; Humanities and Social Sciences; Models, Theoretical; multidisciplinary; Nesting; Ratios; Science; Science (multidisciplinary); Seasons; Sex determination; Sex Determination Processes; Sex Ratio; Sexes; Temperature; Temperature effects; Turtles
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-17708-0

Patterns of temperature fluctuations in nature affect numerous biological processes, yet, empirical studies often utilize constant temperature treatments. This can limit our understanding of how thermally sensitive species respond to ecologically relevant temperatures. Research on turtles with temperature-dependent sex determination (TSD) provides good examples of this, since nest temperatures from many populations rarely exceed those necessary to produce females under constant laboratory conditions. We hypothesized that exposure to brief periods of warm temperatures (i.e., heat waves) are integral to sex determination in species with TSD, which requires tests that move beyond constant temperatures. We exposed
Trachemys scripta
embryos from multiple populations and across the nesting season to heat waves of variable durations and quantified sex ratios. We found that embryos from all populations were highly sensitive to brief exposures to female producing temperatures; only 7.9 days of exposure produced a 50:50 sex ratio, but the response varied across the nesting season. From these findings, a model was developed to estimate sex ratios from field temperature traces, and this model outperformed traditional methods. Overall, these results enhance our understanding of TSD and emphasize the importance of using biologically relevant temperatures when studying thermally sensitive processes.