The mechanism of temperature dependent sex determination in crocodilians: a hypothesis
The mechanism of temperature dependent sex determination in crocodilians: a hypothesis
复制标题
鳄鱼温度依赖性性别决定机制：一个假设
DOI：
--
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
M. Ferguson
中科院分区：
文献类型：
--
作者：
D. Deeming;M. Ferguson
鳄鱼蛋在30°C下孵化产生100%的雌性，在33°C下产生100%的雄性;温度之间产生不同的性别比例。密西西比短吻鳄的野生巢穴表现出类似的效果，种群偏向于女性。本文综述了其它鳄鱼温度依赖性性别决定（TSD）的发生率和模式。温度也影响幼体的大小和色素沉着模式，孵化后的生长速度和青少年鳄鱼的体温调节。温度变化实验所定义的温度敏感期的意义是质疑有关的一个假设来解释鳄鱼TSD的机制。据推测，有一个初始的性别分化机制，涉及一个量子的时间段和一个阈值的剂量的男性决定因素。诱导雄性的条件是精确的，但在种群内个体之间存在差异。雌性的发育是默认的。下丘脑可能在后期性别分化机制中起重要作用。这一假说被用来解释高温到低温转换实验所定义的后期温度敏感期，为什么较低的温度更有效地确定性别，中间温度如何产生两性，海龟和鳄鱼之间的模式差异以及鳄鱼内TSD模式的地理相似性，尽管气候不同。TSD在鳄鱼中的系统发育优势与动物的总体生殖策略有关。那些在最佳环境条件下孵化和生长成熟的鳄鱼将是大型和雄性的。较大的雄性更有可能产生更多的后代。对环境对两栖动物和鱼类性别决定的影响的综述表明，脊椎动物的大小和性别之间存在着普遍的关系
Incubation of alligator eggs at 30°C produces 100% females, at 33°C 100% males; temperatures in between produce varying sex ratios. Wild nests of Alligator mississippiensis show similar effects and the populations are biased towards females. The incidence and patterns of temperature dependent sex determination (TSD) in other crocodilians are reviewed. Temperature also affects hatchling size and pigmentation patterns, post-hatching growth rates and thermoregulation by juvenile crocodilians. The significance of temperature sensitive periods defined by temperature shift experiments is questioned in relation to a hypothesis to explain the mechanism of TSD in crocodilians. It is postulated that there is an initial sex differentiation mechanism which involves a quantum period of time and a threshold for a dose of a male determining factor. The conditions for induction of males are precise but exhibit variation between individuals within the population. Females develop by default. The hypothalamus may have an important role in a later sex differentiation mechanism. The hypothesis is used to explain the late temperature sensitive periods defined by high to low temperature shift experiments, why cooler temperatures are more effective at determining sex, how intermediate temperatures can produce both sexes, the differences in the pattern between turtles and crocodilians and geographical similarities in the pattern of TSD within crocodilians despite differing climates. The phylogenetic advantages of TSD in crocodilians are concerned with the overall reproductive strategy of the animals. Those crocodilians which are incubated and grow to maturity under optimal environmental conditions will be both large and male. Larger males are more likely to produce more offspring. A review of the effects of the environment on sex determination in amphibians and fish suggests that there is a general relationship between size and sex in vertebrates
DOI：
10.1098/rstb.1988.0110
发表时间：
1988
期刊：
Philosophical transactions of the Royal Society of London. Series B, Biological sciences
影响因子：
--
作者：
Kimble,J
通讯作者：
Kimble,J