Search

Studies of sexual communication typically focus on the design and information content of a signal of interest, but the timing of signal production relative to nearby competitors can be crucial. Male fiddler crabs, Uca mjoebergi, court females with a stereotyped claw-waving display, and males are often observed waving in synchrony with nearby claw-waving males. Using female mate preference experiments with robots that imitate male claw waves, we found evidence that females are more attracted to males whose waves immediately precede a synchronous group of waves (leaders); females also favoured males that waved in opposite phase to a synchronous group (alternators). By contrast, males whose waves lagged behind a group of synchronous wavers (laggards) were no more attractive. We discuss a simple sensory process that could explain how this female preference arises. Our results agree with past findings suggesting that synchrony in fiddler crabs occurs as an epiphenomenon of adaptive male responses to female preferences.

As recently outlined in TREE [1], many animals and plants are thought to load their male gametes with multiple types of RNA, some of which enters the oocyte upon fertilization. Four classes of ultimate hypotheses for sperm RNA were proposed [1], adding to existing mechanistic hypotheses [2]. We suggest two more ultimate hypotheses to be considered when investigating sperm RNA. Throughout, we only consider sperm RNA deriving from the diploid male genome.