Growth-independent effects of temperature on age and size at maturity in Japanese medaka (Oryzias latipes)
Growth-independent effects of temperature on age and size at maturity in Japanese medaka (Oryzias latipes)
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DOI：
10.1643/ci-02-098r1
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发表时间：
2004-02-09
期刊：
影响因子：
2.6
通讯作者：
Fox, MG
中科院分区：
文献类型：
--
作者：
Dhillon, RS;Fox, MG
在变温动物中，年龄和成熟时的长度通常随着温度的升高而降低；然而，尚不清楚这种情况是否会在幼鱼生长速度加快的情况下发生，而幼鱼生长速度通常与温暖的热环境有关。我们研究了（1）在没有生长效应的情况下生活史性状是否会受到温度的影响，以及（2）更快的生长速度会导致成熟时年龄和体型的减小。日本青鳉暴露在 24、27、30 和 33°C 的温度下，并随意喂食（在所有温度下）或限制喂食（在较高温度下），以均衡不同热状态下的生长速度。当饲养温度从 24 摄氏度升高到 30 摄氏度时，即使体细胞生长速度相同，成熟时的年龄和体型都会下降。然而，随着温度从30°C进一步升高到33°C，成熟时的年龄和身长实际上也增加了。与给予限制性口粮并在相同温度下饲养的青鳉相比，给予自由口粮的青鳉生长得更快，成熟更早，体型也更大。我们得出的结论是，温度可以影响鱼类的生活史特征，而与温度对体细胞生长的影响无关。然而，当温度接近物种的最大耐受性并且食物供应量低到足以对鱼类可用的剩余能量施加严格限制时，效果的方向可能会逆转。在这种情况下，最高温度下生活史效应的意外逆转可能是由于青鳉正常性腺发育受到干扰造成的。
In ectotherms, age, and length at maturity typically decrease with an increase in temperature; however, it is unclear whether this occurs in the absence of accelerated juvenile growth rates that are usually associated with,warmer thermal regimes. We investigated whether (1) life-history traits are affected by temperature in the absence of a growth effect, and (2) faster growth rates cause a reduction in age and size at maturity. Japanese Medaka were exposed to temperatures of 24, 27, 30, and 33 C and fed either ad libitum rations (at all temperatures) or limiting rations (at higher temperatures) to equalize growth rates across thermal regimes. Both age and size at maturity decreased as rearing temperature increased from 24 to 30 C, even when somatic growth rates were equivalent. However, age and length at maturity actually increased with a further temperature increase from 30 to 33 C. Medaka given ad libitum rations grew faster and matured earlier and at a larger size than those given limiting rations and reared at the same temperature. We conclude that temperature can affect the life-history traits of fishes independently of any effect of temperature on somatic growth. However, the direction of the effect may be reversed when the temperature approaches the maximum tolerance of the species and when food availability is low enough to impose severe limits on the amount of surplus energy available to the fish. In this case, the unexpected reversal of life-history effects at the highest temperature may have been caused by the disturbance of normal gonadal development in Medaka.