Advances on the interplay of learning and sexual selection

Sexual selection has continued to be a popular focus of research in evolutionary biology since its rise to prominence around the 1970s and 1980s (e.g., Andersson, 1994). Active debate still remains about many of the fundamental processes of sexual selection (e.g., Parker and Pizzari, 2015, Hill, 2015); despite the fact that the field originated in the time of Darwin (1859, 1871) some basic principles remain unresolved. Furthermore, the way that sexual selection interacts with, and is affected by, other processes and phenomena has also attracted a lot of attention. One research area that originated decades ago but has received an increasing amount of notice in recent years is the fact that mating cues (“traits”), preferences, and other aspects of the sexual selection process may often display phenotypic plasticity (reviewed in Price, 2006; Ingleby et al., 2010, Rodriguez et al., 2013, Ah-King and Gowaty, 2015). One of the manifestations of plasticity is the alteration of trait and preference phenotypes by learning. When traits or preferences are passed on solely through learning or imprinting they are said to be culturally inherited. These phenotypes may not have a genetic basis, but are instead ultimately determined by others in the animal’s surroundings. Individuals, for example, may learn a trait or mating preference from their mother (maternal imprinting), father (paternal imprinting) or from adults in the population at large (oblique imprinting). Mating preferences and traits may also be formed by learning from previous experience (e.g., behavioral reinforcement) or by copying the mating preferences of others (see reviews in Freeberg, 2000; White, 2004; Galef and Laland, 2005; Verzijden et al., 2012). The effect of cultural learning or inheritance could potentially be absolute in the sense of resulting in a phenotype that is solely culturally determined, as described above, but in many cases cultural factors will instead combine with genetic ones to determine a phenotype. In either of these cases cultural (or partly-cultural) and genetic traits can affect one another, resulting in gene-culture coevolution (reviewed in Boyd and Richerson, 1985; Feldman and Laland, 1996; Aoki 2001). Research at the intersection of learning and sexual selection has benefitted from attention from both empirical and theoretical studies. Evidence has been accumulating from a wide variety of taxa to indicate that learning can be important in the development of mating preferences and traits (reviewed in Verzijden et al., 2012; see also e.g., Guevara-Fiore, 2012; Westerman et al., 2014; Holveck and Reibel, 2014). In such species, learning of preferences (including courtship preferences) and/or traits (such as songs or displays) can ultimately affect species recognition (e.g., in birds: Grant and Grant, 1997; Price, 1998; ten Cate and Vos, 1999; Sorenson et al., 2003; in insects: Dukas, 2004, 2008; Svensson et al., 2010, 2014; in mammals: Kendrick et al.,1998, in fish: Magurran and Ramnarine, 2004; Verzijden and ten Cate, 2007; Kozak and Boughman, 2009; Kozak et al., 2011). There has also been a rich theoretical literature on the interaction of cultural evolution with sexual selection (e.g., Aoki, 1989; Kirkpatrick and Dugatkin, 1994; Laland, 1994a, b; Servedio and Kirkpatrick, 1996; Agrawal, 2001; Aoki et al., 2001; Ihara et al., 2003; Tramm and Servedio, 2008; Dubois et al., 2012; Chaffee et al., 2013; Santos et al., 2014). The new papers in this column contribute to both our empirical (Dukas and Scott, 2015; Fowler-Finn et al., 2015; Verzijden et al., 2015) and theoretical (Invernizzi and Gilman, 2015; Morier-Genoud and Kawecki, 2015) understanding of the ways in which learning and mate choice interact, in addition to providing a review of current issues in one particularly rich area of research on learning and sexual selection – mate choice copying (Witte et al., 2015).