Ovulated female salamander (Hynobius leechii) respond to water currents

Abstract

To determine whether or not the female Korean salamander, Hynobius leechii, responds to water currents and, if so, whether those responses depend on their reproductive conditions, we evaluated the responses of ovulated and oviposited females to 1-Hz water currents generated by a model salamander with and without the placement of a transparent water current blocker between the model and the test females. The ovulated females responded to water currents by turning their heads toward, approaching, and/or making physical contact with the model. When the water current blocker was in place, the number of salamanders that approached the model was reduced significantly. The approaching and touching responses of ovulated females were greater than those of oviposited females, whereas the other measurements evidenced no differences. None of the responses of the oviposited females to water currents was affected by the presence of the blocker. Our results indicate that female H. leechii responds to water currents via a mechanosensory system. Key words: body undulation, courtship behavior, mechanosensory system, oviposition, ovulation, water current INTRODUCTIONIn many animal taxa, the mechanosensory system performs a critical function in a variety of activities, including conspecific and individual recognition, alarm response, foraging, and reproduction (Vogel and Bleckmann 1997, Baker and Montgomery 1999, Hill 2001, Quirici and Costa 2007, McHenry et al. 2009). The functions of the mechanosensory system in reproduction have been assessed in different animal species, including rotifers (Joanidopoulos and Marwan 1999), spiders (Maklakov et al. 2003, Quirici andCosta 2007) and salmon (Satou et al. 1994a); such studies demonstrated that a healthy mechanosensory system is crucial for successful reproduction. Urodela species possess a well-developed mechanosensory system (Lannoo 1987, Lee andPark 2008b), the functions of which in foraging and predation have been relatively well-studied (Fritzsch and Neary 1998). However, the reproductive functions of this system have yet to be wellestablished.Unlike the majority of other salamanders, salamanders in the Hynobiidae fertilize eggs externally (Salthe 1967). When a Hynobius male and female encounter one another, the male salamander performs body undulations when its snouts are in contact with the female's skin (Tanaka 1986, Park and Park 2000, Kim et al. 2009). Body undulation is defined as an intermittent undulation of the body trunk and tail, which generates water currents. Male H. takedai respond to surface water currents generated by a glass rod, and H. nigrescens Field Biol. 33(3): 217-222, 2010 responds to the body undulation of other males (Tanaka 1987, Usuda 1995. A recent study also demonstrated that H. leechii males respond to water currents generated by other males using their mechanosensory system (Park et al. 2008, Kim et al. 2009).Previous studies have demonstrated that when Hynobius females are nearing oviposition, they approach a tree twig or rocks, rub their cloa...