Kamio Michiya, Reidenbach Matthew A, Derby Charles D
Department of Biology, Brains & Behavior Program, and Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA 30302, USA.
J Exp Biol. 2008 Apr;211(Pt 8):1243-8. doi: 10.1242/jeb.014977.
The nature of the courtship signalling used by a species is shaped by many factors, one of which is its habitat. Male blue crabs, Callinectes sapidus, have a courtship display in which they elevate their body by standing high on their legs, open their chelae and paddle their swimming legs. This courtship display is not reported in other swimming (portunid) crabs and is rarely expressed in laboratory experiments on male blue crabs. In this study, we characterised this display, which we call ;courtship stationary paddling', and distinguished it from other types of paddling. To explain the species specificity of courtship stationary paddling, we hypothesised that this behaviour is an adaptation to low visibility and abundant refuges in the habitat of blue crabs, and that this behaviour enhances chemical signalling when females are relatively inaccessible to males. We used particle imaging velocimetry to visualise water currents generated during courtship stationary paddling, showing that it created water currents directed away from the male and towards the female, thus enhancing chemical signalling. We also showed that males did not perform courtship stationary paddling when females were freely walking such that males could quickly contact and cradle carry them. Rather, males typically performed courtship stationary paddling only when females were inaccessible to them. These results indicate that courtship stationary paddling is a context-dependent behaviour, occurring only when females are not accessible to males, and suggesting that it evolved as an adaptation to life in habitats with many refuges and low visibility.
一个物种所使用的求偶信号的性质受到多种因素的影响，其中之一是其栖息地。雄性蓝蟹（学名：Callinectes sapidus）有一种求偶展示行为，它们用腿高高站立使身体抬高，张开螯足并划动游泳足。这种求偶展示在其他游泳蟹类（梭子蟹科）中并未有报道，并且在对雄性蓝蟹的实验室实验中也很少表现出来。在本研究中，我们对这种展示行为进行了特征描述，将其称为“求偶静止划动”，并将其与其他类型的划动区分开来。为了解释求偶静止划动的物种特异性，我们推测这种行为是对蓝蟹栖息地能见度低且避难所丰富的一种适应，并且当雄性相对难以接近雌性时，这种行为会增强化学信号传递。我们使用粒子图像测速技术来可视化求偶静止划动过程中产生的水流，结果表明它产生了从雄性指向雌性的水流，从而增强了化学信号传递。我们还表明，当雌性自由行走以至于雄性能够迅速接触并抱住它们时，雄性不会进行求偶静止划动。相反，雄性通常仅在无法接近雌性时才会进行求偶静止划动。这些结果表明，求偶静止划动是一种依赖于环境的行为，仅在雄性无法接近雌性时才会发生，这表明它是作为对生活在有许多避难所且能见度低的栖息地的一种适应而进化出来的。
