TY - JOUR
T1 - The effect of hormone manipulations on sex ratios varies with environmental conditions in a turtle with temperature-dependent sex determination
AU - Warner, Daniel A.
AU - Mitchell, Timothy S.
AU - Bodensteiner, Brooke L.
AU - Janzen, Fredric J.
N1 - Publisher Copyright:
© 2017 Wiley Periodicals, Inc.
PY - 2017/4
Y1 - 2017/4
N2 - Exogenous application of steroids and related substances to eggs affects offspring sex ratios in species with temperature-dependent sex determination (TSD). Laboratory studies demonstrate that this effect is most pronounced near the constant temperature that produces 1:1 sex ratios (i.e., pivotal temperature). However, the impact of such chemicals on sex determination under natural nest temperatures (which fluctuate daily) is unknown, but could provide insight into the relative contributions of these two factors under natural conditions. We applied estradiol (E2) and an aromatase inhibitor (fadrozole) to eggs of the painted turtle (Chrysemys picta), a species with TSD, and allowed eggs to incubate under natural conditions during two field seasons (in 2012 and 2013). Exogenous E2, fadrozole, and nest temperature contributed to variation in offspring sex ratio, but the relative contributions of these factors differed between years. In 2012, a much hotter than average season, sex ratios were heavily female biased regardless of nest temperature and chemical treatment. However, in 2013, a milder season, both nest temperature and chemical treatment were important. Moreover, a significant interaction between nest temperature and treatment demonstrated that exogenous estradiol induces female development regardless of nest temperature, but aromatase inhibition widens the range of temperatures that produces both sexes.
AB - Exogenous application of steroids and related substances to eggs affects offspring sex ratios in species with temperature-dependent sex determination (TSD). Laboratory studies demonstrate that this effect is most pronounced near the constant temperature that produces 1:1 sex ratios (i.e., pivotal temperature). However, the impact of such chemicals on sex determination under natural nest temperatures (which fluctuate daily) is unknown, but could provide insight into the relative contributions of these two factors under natural conditions. We applied estradiol (E2) and an aromatase inhibitor (fadrozole) to eggs of the painted turtle (Chrysemys picta), a species with TSD, and allowed eggs to incubate under natural conditions during two field seasons (in 2012 and 2013). Exogenous E2, fadrozole, and nest temperature contributed to variation in offspring sex ratio, but the relative contributions of these factors differed between years. In 2012, a much hotter than average season, sex ratios were heavily female biased regardless of nest temperature and chemical treatment. However, in 2013, a milder season, both nest temperature and chemical treatment were important. Moreover, a significant interaction between nest temperature and treatment demonstrated that exogenous estradiol induces female development regardless of nest temperature, but aromatase inhibition widens the range of temperatures that produces both sexes.
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U2 - 10.1002/jez.2085
DO - 10.1002/jez.2085
M3 - Article
C2 - 29356364
AN - SCOPUS:85044404824
SN - 2471-5638
VL - 327
SP - 172
EP - 181
JO - Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
JF - Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
IS - 4
ER -