Relative Abundance of Xiphophorus Fishes and Its Effect on Sexual Communication

Populations often show striking differences between one another, particularly in terms of male sexual traits and female preferences (Hill 1994; Endler & Houde 1995; Verrell 1999). In particular, the ecological community an individual is exposed to can have a great impact on its behavior. The proportion of predators, for example, can increase risk of sexual signaling and impose constraints on mate traits and female preferences, as seen in the guppy, Poecilia reticulata (Stoner & Breden 1988; Godin & Briggs 1996). Sympatric congeners can also influence sexual communication since selection to avoid hybridization may favor signal divergence (Howard 1993; Servedio & Noor 2003; Coyne & Orr 2004). For example, it is often observed that sympatric species partition acoustic communication channels (Drewry & Rand 1983; Duellman & Pyles 1983; Wilczynski et al. 1993). Similiarly, in Lake Victoria, sympatrically living, closely related haplochromine male cichlids often differ by color (Seehausen et al. 1997). Furthermore, sympatric heterospecifics may influence receiver behavior, in addition to signal evolution, by altering female preferences for conspecifics (e.g., Gerhardt 1994; Höbel & Gerhardt 2003; Pfenning 2000; Saetre et al. 1997). Correspondence Heidi S. Fisher, Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford St., Cambridge, MA 02138, USA. E-mail: [email protected]