The Devil is in the Details: Identifying Aspects of Temperature Variation that Underlie Sex Determination in Species with TSD
The Devil is in the Details: Identifying Aspects of Temperature Variation that Underlie Sex Determination in Species with TSD
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DOI：
10.1093/icb/icz036
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发表时间：
2019-10-01
影响因子：
2.6
通讯作者：
Bowden, R. M.
中科院分区：
文献类型：
--
作者：
Carter, A. W.;Paitz, R. T.;Bowden, R. M.
大多数生物体在其环境中经历热变化;然而，我们对生物体如何科普这种变化的理解尚不充分。例如，在具有温度依赖性性别决定（TSD）的生物中，无法预测野外孵化温度波动下的性别比例，这阻碍了对TSD物种在气候变化中的表现的预测。为了更好地了解性别决定如何受到热变化的影响，我们使用“热浪”设计孵育Trachemys scripta卵，其中胚胎在大多数发育过程中经历了25 +/- 3摄氏度的雄性产生温度，并在确定性别的发育窗口期间在29.5 +/- 3摄氏度的雌性产生温度下持续不同的时间。我们将这些孵化条件下的性别比例与之前的数据集进行了比较，该数据集使用了类似的热浪设计，但在27 +/- 3摄氏度的雄性生产温度下孵化鸡蛋，但使用了相同的雌性生产温度29.5 +/- 3摄氏度。我们比较了这两种孵育条件下产生的性比反应标准，发现尽管平均温度不同，但在暴露于产生雌性的条件下8天后，两种条件下产生的性比均为50：50。这强调了性别可以在短短几天内在雌性生产条件下确定，并且性别决定相对不受这个短窗口之外的温度的影响。此外，这些数据表明，恒温等效模型（预测性别比的主要方法）在热变温度下的准确性降低。概念化的性别决定的天数孵化在女性生产的条件下，而不是一个总的统计数据是支持的机械基础的TSD，有助于改善性别比估计方法，并预测如何与TSD物种将在不断变化的气候中表现出重要的后果。
Most organisms experience thermal variability in their environment; however, our understanding of how organisms cope with this variation is under-developed. For example, in organisms with temperature-dependent sex determination (TSD), an inability to predict sex ratios under fluctuating incubation temperatures in the field hinders predictions of how species with TSD will fare in a changing climate. To better understand how sex determination is affected by thermal variation, we incubated Trachemys scripta eggs using a "heat wave" design, where embryos experienced a male-producing temperature of 25 +/- 3 degrees C for the majority of development and varying durations at a female-producing temperature of 29.5 +/- 3 degrees C during the window of development when sex is determined. We compared the sex ratios from these incubation conditions with a previous data set that utilized a similar heat wave design, but instead incubated eggs at a male-producing temperature of 27 +/- 3 degrees C but utilized the same female-producing temperature of 29.5 +/- 3 degrees C. We compared the sex ratio reaction norms produced from these two incubation conditions and found that, despite differences in average temperatures, both conditions produced 50:50 sex ratios after similar to 8days of exposure to female-producing conditions. This emphasizes that sex can be determined in just a few days at female-producing conditions and that sex determination is relatively unaffected by temperatures outside of this short window. Further, these data demonstrate the reduced accuracy of the constant temperature equivalent model (the leading method of predicting sex ratios) under thermally variable temperatures. Conceptualizing sex determination as the number of days spent incubating at female-producing conditions rather than an aggregate statistic is supported by the mechanistic underpinnings of TSD, helps to improve sex ratio estimation methods, and has important consequences for predicting how species with TSD will fare in a changing climate.