拟环纹豹蛛雄蛛触肢上黑白相间毛饰物的功能

狼蛛科雄蛛附肢上多样化的饰装往往与求偶行为相偶联,这些特殊的饰装通常被认为是雌性选择的结果。拟环纹豹蛛Pardosa pseudoannulata,属狼蛛科豹蛛属,雄蛛触肢胫节密被白毛,跗舟密被黑毛,具有典型的性二型现象;同时,只有成熟的雄蛛才展现触肢黑白相间的毛饰物。推测拟环纹豹蛛雄蛛触肢这种黑白相间的毛饰物可能在物种识别中具重要作用。在室内我们拟通过涂抹操作对拟环纹豹蛛雄蛛触肢黑白相间毛饰物的功能进行分析。实验分为4组,分别是对照组(A组,雄蛛不做任何处理)、雄蛛触肢白色胫节全部涂成黑色(B组)、雄蛛触肢黑色跗舟全部涂成白色(C组)和雄蛛触肢的黑色跗舟被涂成黑色(D组),然后采用雌雄配对进行求偶交配行为测定。实验结果表明,B组雄蛛的交配成功率显著低于A、C和D组的雄蛛,而后3组雄蛛的交配成功率无显著差异。相反,B组雄蛛被雌蛛相食百分率显著高于其它3组。可见拟环纹豹蛛雄蛛触肢上黑白相间毛饰物,尤其是其胫节上的白色饰物在雌蛛种间识别中起重要作用。

The function of the black and white ornaments on male pedipalps inthe wolf spider Pardosa pseudoannulata

Sexual selection has long been recognized as a driving force in shaping reproductive characteristics and hence in promotion of speciation. Elaborate ornamentation and courtship displays are among the most visible consequences of sexual selection. Sexual selection generally includes male-male competition and female mate choice. There are three levels of mate choice: species recognition, mate recognition, and mate assessment. Species recognition is the prerequisite for mate choice. In a wide range of wolf spider species in the family Lycosidae, males display a bewildering diversity of ornaments that have presumably evolved under the influence of female mate choice. Most studies on the function of male ornaments in lycosids have primarily focused on the genus Schizocosa and shown that conspicuous visual ornaments on male forelegs are frequently incorporated into complex courtship displays. Nonetheless, such secondary sexual traits of male wolf spiders in the genus Schizocosa do not play a vital role in female mate choice. In order to elucidate the origin and evolution of male ornaments among wolf spiders, comparative studies are needed. Few studies have addressed the function of male ornaments in other lycosid genera, such as Pardosa. The courtship displays of Pardosa males are characterized by complex movements of the pedipalps. The wolf spider, Pardosa pseudoannulata, is among dominant predators in paddy fields. P. pseudoannulata males have pedipalps with white tibia and black cymbium. When the males encounter sexually receptive females, they usually display courtship behavior by rowing their white and black pedipalps. It is assumed that complex movements of the white and black pedipalps may perform an important function in species recognition in P. pseudoannulata. In this study, we tested this hypothesis by manipulating male white and black pedipalps: Group A (control group; male pedipalps were not painted), Group B (white tibias of male pedipalps were painted black), Group C (the black cymbium of male pedipalps was painted white), and Group D (the black cymbium of male pedipalps was painted black). We then randomly paired individual males with 3-day-old virgin females and examined male mating success and female cannibalism. The mating success of Group B males was significantly lower than that of Groups A, C, and D, whereas no significant difference in male mating success was observed among Groups A, C, and D. In contrast, the rate of female cannibalism in Group B was significantly higher than that in the other three groups. We concluded that the white and black hairy ornaments on pedipalps of male P. pseudoannulata may be important for species recognition. We cannot rule out female mate choice.