Bray Joel, Samson David R, Nunn Charles L
School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona.
Department of Evolutionary Anthropology, Duke University, Durham, North Carolina.
Am J Primatol. 2017 Jun;79(6). doi: 10.1002/ajp.22648. Epub 2017 Mar 3.
Cathemerality, or activity throughout the 24-hr cycle, is rare in primates yet relatively common among lemurs. However, the diverse ecological conditions under which cathemerality is expressed complicates attempts to identify species-typical behavior. For example, Lemur catta and Varecia have historically been described as diurnal, yet recent studies suggest that they might exhibit cathemeral behavior under some conditions. To investigate this variation, we monitored activity patterns among lemurs that are exposed to similar captive environments. Using MotionWatch 8 ® actigraphy data loggers, we studied 88 lemurs across seven species at the Duke Lemur Center (DLC). Six species were members of the family Lemuridae (Eulemur coronatus, E. flavifrons, E. mongoz, L. catta, V. rubra, V. variegata), while a seventh was strictly diurnal and included as an out-group (Propithecus coquereli). For each 24-hr cycle (N = 503), we generated two estimates of cathemerality: mean night (MN) activity and day/night (DN) activity ratio (day and night cutoffs were based on astronomical twilights). As expected, P. coquereli engaged in the least amount of nocturnal activity according to both measures; their activity was also outside the 95% confidence intervals of all three cathemeral Eulemur species, which exhibited the greatest evidence of cathemerality. By these estimates, Varecia activity was most similar to Eulemur and exhibited substantial deviations from P. coquereli (β (MN) = 0.22 ± SE 0.12; β (DN) = -0.21 ± SE 0.12). L. catta activity patterns also deviated from P. coquereli (β (MN) = 0.12 ± SE 0.11; β (DN) = -0.15 ± SE 0.12) but to a lesser degree than either Varecia or Eulemur. Overall, L. catta displayed an intermediate activity pattern between Eulemur and P. coquereli, which is somewhat consistent with wild studies. Regarding Varecia, although additional observations in more diverse wild habitats are needed, our findings support the existence of cathemeral behavior in this genus.
全天性活动，即在24小时周期内均有活动，在灵长类动物中较为罕见，但在狐猴中相对常见。然而，全天性活动所表现出的多样生态条件使得识别物种典型行为变得复杂。例如，环尾狐猴和大狐猴在历史上一直被描述为昼行性动物，但最近的研究表明，它们在某些条件下可能表现出全天性活动。为了研究这种变化，我们监测了处于相似圈养环境中的狐猴的活动模式。我们使用MotionWatch 8®活动记录仪，在杜克狐猴中心（DLC）对七个物种的88只狐猴进行了研究。六个物种属于狐猴科（冠美狐猴、黄额美狐猴、獴美狐猴、环尾狐猴、红大狐猴、斑纹大狐猴），而第七个物种是严格的昼行性动物，作为外类群（柯氏冕狐猴）。对于每个24小时周期（N = 503），我们生成了两个全天性活动的估计值：平均夜间（MN）活动和昼/夜（DN）活动比率（白天和夜晚的界限基于天文晨昏蒙影）。正如预期的那样，根据这两种测量方法，柯氏冕狐猴的夜间活动量最少；它们的活动也超出了所有三种全天性活动的美狐猴物种的95%置信区间，这三种美狐猴物种表现出最明显的全天性活动迹象。通过这些估计，大狐猴的活动与美狐猴最为相似，并且与柯氏冕狐猴有显著差异（β（MN）= 0.22±标准误0.12；β（DN）= -0.21±标准误0.12）。环尾狐猴的活动模式也与柯氏冕狐猴不同（β（MN）= 0.12±标准误0.11；β（DN）= -
