TEMPERATURE-DEPENDENT TURNOVERS IN SEX-DETERMINATION MECHANISMS: A QUANTITATIVE MODEL
TEMPERATURE-DEPENDENT TURNOVERS IN SEX-DETERMINATION MECHANISMS: A QUANTITATIVE MODEL
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DOI：
10.1111/j.1558-5646.2010.01098.x
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发表时间：
2011-01-01
期刊：
影响因子：
3.3
通讯作者：
Perrin, Nicolas
中科院分区：
文献类型：
--
作者：
Grossen, Christine;Neuenschwander, Samuel;Perrin, Nicolas
性别决定通常被视为一个二分过程：个体性别被认为是由遗传（基因型性别决定，GSD）或环境因素（环境性别决定，ESD）决定的，最常见的是温度（温度性别决定，TSD）。我们赞同另一种观点，即将 GSD 和 TSD 视为连续体的两端。这两种效应先验地相互作用，因为温度可以影响性别决定级联中任何步骤的基因表达。我们建议通过遗传因素与环境因素导致的表型性别差异的比例，在群体（而不是个体）水平上定义性别决定系统，并在定量遗传学框架中形式化这一概念。性别被视为责任因素背后的阈值特征，反应规范允许对基因型和温度效应之间的相互作用进行建模（被视为热力学约束对潜在生理过程的必然后果）。正如这种形式化所示，温度变化（由于例如气候变化或范围扩大）预计会引起大规模的性别逆转，从而引起替代性别决定基因的性别比例选择，从而引发性别决定机制的转变。因此，冷血脊椎动物中同态性染色体的更替频率和普遍性可能与性别决定机制中的温度依赖性直接相关。
Sex determination is often seen as a dichotomous process: individual sex is assumed to be determined either by genetic (genotypic sex determination, GSD) or by environmental factors (environmental sex determination, ESD), most often temperature (temperature sex determination, TSD). We endorse an alternative view, which sees GSD and TSD as the ends of a continuum. Both effects interact a priori, because temperature can affect gene expression at any step along the sex-determination cascade. We propose to define sex-determination systems at the population- (rather than individual) level, via the proportion of variance in phenotypic sex stemming from genetic versus environmental factors, and we formalize this concept in a quantitative-genetics framework. Sex is seen as a threshold trait underlain by a liability factor, and reaction norms allow modeling interactions between genotypic and temperature effects (seen as the necessary consequences of thermodynamic constraints on the underlying physiological processes). As this formalization shows, temperature changes (due to e.g., climatic changes or range expansions) are expected to provoke turnovers in sex-determination mechanisms, by inducing large-scale sex reversal and thereby sex-ratio selection for alternative sex-determining genes. The frequency of turnovers and prevalence of homomorphic sex chromosomes in cold-blooded vertebrates might thus directly relate to the temperature dependence in sex-determination mechanisms.