Koteja P, Garland T, Sax JK, Swallow JG, Carter PA
Department of Zoology, University of Wisconsin, Madison
Anim Behav. 1999 Dec;58(6):1307-1318. doi: 10.1006/anbe.1999.1270.
We have developed a novel model to study the correlated evolution of behavioural and morphophysiological traits in response to selection for increased locomotor activity. We used selective breeding to increase levels of voluntary wheel running in four replicate lines of laboratory house mice, Mus domesticus, with four random-bred lines maintained as controls. The experiment presented here tested for correlated behavioural responses in the wheel-cage complex, with wheels either free to rotate or locked (environmental factor). After 13 generations, mice from selected lines ran 2.2 times as many revolutions/day as controls on days 5 and 6 of initial exposure to wheels (10 826 versus 4890 revolutions/day, corresponding to 12.1 and 5.5 km/day, respectively). This increase was caused primarily by mice from selected lines running faster, not more minutes per day. Focal-animal observations confirmed that the increase in revolutions/day involved more actual running (or climbing in locked wheels), not an increase in coasting (or hanging). Not surprisingly, access to free versus locked wheels had several effects on behaviour, including total time spent in wheels, sniffing and biting. However, few behaviours showed statistically significant differences between the selected and control lines. Selection did not increase the total time spent in wheels (either free or locked), the frequency of nonlocomotor activities performed in the wheels, nor the amount of locomotor activity in cages attached to the wheels; as well, selection did not decrease the amount of time spent sleeping. Thus, wheel running is, at the genetic level, a largely independent axis of behaviour. Moreover, the genetic architecture of overall wheel running and its components seem conducive to increasing total distance moved without unduly increasing energy or time-related costs. The selection experiment also offers a new approach to study the proximate mechanisms of wheel-running behaviour itself. For example, frequencies of sniffing and wire biting were reduced in selected females but not males. This result suggests that motivation or function of wheel running may differ between the sexes. Copyright 1999 The Association for the Study of Animal Behaviour.
我们开发了一种新模型，用于研究行为和形态生理特征的协同进化，以应对因增加运动活动而进行的选择。我们采用选择性育种的方法，提高了四个重复品系的实验小鼠（小家鼠）自愿跑轮的水平，同时将四个随机繁殖品系作为对照。此处展示的实验测试了在轮笼组合中相关的行为反应，其中轮子可以自由旋转或锁定（环境因素）。经过13代后，在最初接触轮子的第5天和第6天，选系小鼠每天的跑圈数是对照组的2.2倍（分别为10826圈/天和4890圈/天，相当于每天12.1公里和5.5公里）。这种增加主要是因为选系小鼠跑得更快，而不是每天跑的时间更多。焦点动物观察证实，每天跑圈数的增加涉及更多实际的奔跑（或在锁定轮子上攀爬），而不是滑行（或悬挂）的增加。不出所料，使用自由旋转与锁定的轮子对行为有多种影响，包括在轮子上花费的总时间、嗅闻和啃咬。然而，在选系和对照品系之间，很少有行为表现出统计学上的显著差异。选择并没有增加在轮子上花费的总时间（无论是自由旋转还是锁定的轮子）、在轮子上进行的非运动活动的频率，也没有增加连接轮子的笼子中的运动活动量；同样，选择也没有减少睡眠时间。因此，在基因层面上，跑轮是一个在很大程度上独立的行为轴。此外，总体跑轮行为及其组成部分的遗传结构似乎有利于增加移动的总距离，而不会过度增加能量或与时间相关的成本。该选择实验还提供了一种新方法来研究跑轮行为本身的近端机制。例如，选系雌性小鼠嗅闻和咬铁丝的频率降低，但雄性小鼠没有。这一结果表明，跑轮的动机或功能在两性之间可能存在差异。版权所有1999年动物行为研究协会。
