中国科学院昆明动物研究所机构知识库

 节律性是生物生存在这颗蓝色星球上的基本特征之一，其中昼夜节律最为常见，是生命为适应地球自转而产生的日常生活节律。由于昼夜交替，对大多数生物而言，昼夜节律主要表现为夜伏昼出（日行性）和昼伏夜出（夜行性）两种。然而在地球上有一类特殊的洞穴生物，它们终年生活在黑暗无光的洞穴之中，由于光照不再是刺激或制约的因素，其昼夜节律将表现如何？活动强度会如何变化？对于这一特殊群体的生态学、行为学我们仍知之甚少。

洞穴鱼类是适应洞穴生活最为成功的类群之一，在进化生物学、比较生理学研究上都有着巨大的价值。中国作为世界上洞穴鱼类生物多样性最高的地区之一，其整体研究却相对匮乏。特别是中国特有的这些洞穴鱼类在行为生态学方面的研究几乎空白。

本研究通过自行设计的鱼类昼夜节律视频采集装置，利用行为学视频分析软件，采用视频轨迹追踪技术，以生活于地表水体的滇池金线鲃（Sinocyclocheilus grahami）、半洞穴生活的犀角金线鲃（S. rhinocerous）以及完全洞穴生活的安水金线鲃（S. anshuiensis）为研究对象，定量研究了不同光周期下和温度条件下三种实验鱼类的昼夜节律和活动强度，主要结果如下：

1.滇池金线鲃在12L：12D、24D和24L的人工光周期条件下，都表现出了较为明显的昼夜节律，其中晨昏时段活动强度为峰值，在12D：12L人工光周期中没有表现出明显的昼夜节律；整体活动强度24D组最高。

犀角金线鲃在12L：12D人工光周期中表现出极弱的昼夜节律，且夜间活动强度略高于昼间。在24D、24L和12D：12L光周期中都没有表现出明显的昼夜节律。

安水金线鲃在四个组别中均没有表现出明显的昼夜节律，昼夜均沿鱼缸底部和边缘的缓慢持续游动，游动速度非常缓慢，极少出现快速游动的行为，活动强度极低，显著低于前述两种，其中在24D组中活动强度最高。

2.滇池金线鲃在低温组（15℃/12L：12D）中表现出白昼时段活动强度的整体下降，晨昏两个活动高峰的活动强度有较显著的下降，白昼和夜间活动振幅趋于平缓，但整体昼夜节律依然稳定。犀角金线鲃在低温组（15℃/24D）中没有表现出昼夜节律，活动强度略有下降。安水金线鲃在低温组（15℃/24D）中也没有表现出昼夜节律，活动强度略有下降。本研究为中国洞穴金线鲃属鱼类节律退化现象提供了行为学数据的证据，也为今后其人工养殖、繁育和物种保护等提供了理论支持。

Rhythmic is an essential characterisitic of life which is living on this blue planet. The circadian rhythm of creature arose in order to adapt the alternation of day and night caused by the rotation of the earth. Because of the alternation of day and night, for most organisms, circadian rhythm mainly show up in two types as diurnal and nocturnal.However, in the karst cave perennially filled with darkness, lives cavefish, a very special biological group , because the light is no longer a stimulus or restriction factor, how will their circadian rhythm presentation? How will their activity intensity change? For this special group, its ecology and ethology are still little known. Since cavefish is one of the most successful groups to adapt to the subterranean life, the evolutionary biology and comparative physiology have great value. China has the highest biodiversity of cavefish in the world with lots of endemic species , but there is a relative lack of overall research, especially the ethology of Chinese endemic cavefish is almos blank. This article used the fish circadian rhythm video acquisition equipment of our own design,through professional behavioral video analysis software, focused on three species included Sinocyclocheilus grahami inhabits in surface water, S. Rhinocerous and S. Anshuiensis inhabit subterranean, in order to investagate the circadian rhythm and activity intensity under different photoperiod and temperature conditations, the conclusions of the research are as follows: 1.The Sinocyclocheilus grahami showed a distinct bimodality circadian rhythm in both three artificial photoperiod including 12L:12D,24D and 24L groups. There were two peaks of activity which were at dawn and dusk, besides, it didn’t show a obivous circadian rhythm in the 12D:12L artificial photoperiod. The highest summation activity intensity belongs to 24D group. The S. Rhinocerous showed a unconspicuous cirdadian rhythm in the 12D:12L artificial photoperiod, and didn’t show any significant circadian rhythm in 24D,24L and 12D:12L artificial photoperiod. Only in 12L:12D group its nocturnal activity was a bit higher than the diurnal. S. anshuiensis occured no significant circadian rhythm in both four groups , slowly cruising along the bottom of the tank both day and night, while the movement velocity is extremly slow , rarely swimming fast, the total activity intensity is extremly low and significantly lower than the previous two species. The highest summation acitivy intensity belongs to 24D group. 2.The Sinocyclocheilus grahami showed a decrease of diurnal activity in low temprature group (15℃/12L:12D), two peaks of movement activity reduced obviously,amplitude of nocturnal activity tended to reduce as well,but the holistic circadian rhythm remained stable.The S. Rhinocerous showed no obvious circadian rhythm in low temperature group(15℃/24D),no significant reduction in the activity either. S. Anshuiensis didn’t show any daily rhythmic in low temperature group(15℃/24D) ,activty intensity declined slightly. This article provides some evidence for the rhythmic degeneration of Chinese endemic cavefish, and references to the captive breeding and protection of the cave dewlling Sinocyclocheilus as well.