DST-IRHPA Center for Excellence in Biological Rhythm Research, Department of Zoology, University of Lucknow, Lucknow 226 007, India.
Chronobiol Int. 2010 Jan;27(1):111-27. doi: 10.3109/07420520903399680.
This study investigated the effects of a conspecific on survival advantages in a challenged feeding environment created through restricted food availability periods. We measured the daily activity-rest pattern as the circadian response indicator, and changes in body mass and mortality as the survivorship indicator. Migratory male redheaded buntings (Emberiza bruniceps) were housed alone (single, Group 1) or with a conspecific (pair, Group 2) in activity cages that continuously recorded the activity-rest pattern. Cages were individually placed within the isolated photoperiodic boxes providing short-day conditions (8 h light: 16 h darkness, LD 8/16; L = 15 lux; D = 0.5 lux at the cage floor level) with food freely available (ad libitum). Beginning from day 11 of the experiment, food availability was restricted for two weeks to only during the 8 h daytime (zeitgeber time [ZT 0-8]; ZT 0 = time of lights-on). Thus, birds were concurrently subjected to a food zeitgeber cycle, PA 8/16, synchronous (in phase) with the LD 8/16. Thereafter, food availability was changed to only during the 16 h of darkness (ZT 8-0; ZT 8 = time of lights-off). Thus, the food cycle, PA 16/8 (16 h food present: 8 h food absent) was in conflict with the LD 8/16; the LD and PA cycles were in antiphase. This was considered for diurnal redheaded buntings as the challenged feeding environment. After four weeks, singles were returned to the ad libitum food condition; those in pairs remained on the nighttime (darkness) food regimen but were separated to confirm the effects of the nighttime food condition on isolates. The results show that the presence of a conspecific within the cage influenced the daily activity-rest pattern, maintained body mass, and reduced mortality. It is suggested that the presence of a conspecific within the same cage improved the circadian performance of the members forming the pair and enhanced their survivorship.
本研究探讨了在限制食物供应期创造的受挑战的进食环境中，同种个体对生存优势的影响。我们将每日活动-休息模式作为昼夜节律反应的指标，将体重变化和死亡率作为存活指标进行测量。迁徙雄性红头金翅雀（Emberiza bruniceps）单独饲养（单只，第 1 组）或与同种个体成对饲养（第 2 组），饲养在连续记录活动-休息模式的活动笼中。笼子单独放置在提供短日照条件（16 小时光照：8 小时黑暗，LD 8/16；L = 15 lux；笼底水平的 D = 0.5 lux）的隔离光周期箱内，食物自由供应（随意）。从实验的第 11 天开始，食物供应限制为仅在白天 8 小时内（时间生物节律 [ZT 0-8]；ZT 0 =开灯时间）。因此，鸟类同时受到食物时间生物节律周期，PA 8/16 的影响，与 LD 8/16 同步（同相）。此后，食物供应仅在 16 小时黑暗时（ZT 8-0；ZT 8 =关灯时间）进行。因此，食物周期，PA 16/8（16 小时有食物：8 小时无食物）与 LD 8/16 相冲突；LD 和 PA 周期相位相反。这被认为是对昼行红头金翅雀的具有挑战性的进食环境。四周后，单身个体恢复到随意进食状态；成对饲养的个体仍处于夜间（黑暗）食物方案，但分开以确认夜间食物条件对独居个体的影响。结果表明，笼内同种个体的存在影响了每日活动-休息模式，维持了体重，降低了死亡率。这表明，在同一个笼子里有同种个体的存在提高了形成对的成员的昼夜节律表现，并增强了它们的生存能力。
