Female and male phonotactic responses and the potential effect of sexual selection on the advertisement calls of a frog Felipe N. Moreno-G  omez * , Leonardo D. Bacigalupe, Andr  es A. Silva-Escobar, Mauricio Soto-Gamboa Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile article info Article history: Received 17 October 2014 Initial acceptance 6 January 2015 Final acceptance 23 February 2015 Published online MS. number: A14-00832R Keywords: acoustic sexual signal anuran Eupsophus roseus female preference sexual selection The outcome of sexual selection acting on a given sexual trait depends on the interaction between the strength, direction and form of both inter- and intrasexual selection processes. Therefore, determining female choice and maleemale competition is necessary to gain a better understanding of how sexual selection acts on sexual traits. Anuran males produce advertisement vocalizations to attract females and to maintain other males at distance, providing a convenient opportunity to test the combined effect of inter- and intrasexual selection. Our main objective was to test experimentally potential effects of female choice and maleemale competition and their interaction when acting as selective agents on the advertisement vocalizations of the rosy ground frog, Eupsophus roseus. We performed phonotaxis ex- periments on females and males and determined their behavioural responses to artificial signals syn- thesized based on the distribution of natural calls. The main results suggest that females' preference would favour vocalizations having lower frequencies and a harmonic composition in which the main harmonics of vocalizations have similar amplitudes. These preferences suggest that females could exert negative directional sexual selection on the frequency and stabilizing selection on the amplitude ratio. The responses of males were variable, suggesting that this type of maleemale competition may not result in intrasexual selection favouring specific values of advertisement vocalizations. The occurrence of no clear preferences in males may result in a decrease in the potential effect of females' preferences, which could further contribute to variability in spectral components of calls. © 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Female mate choice and maleemale competition are well- known processes affecting the evolution of sexual traits (Andersson, 1994; Andersson & Simmons, 2006; Kokko, Jennions, & Brooks, 2006; Mead & Arnold, 2004). Inter- and intrasexual selec- tion may act on single or correlated sexual traits and also at the same or different times. This implies the existence of complex in- teractions, where inter- and intrasexual selection effects can rein- force or cancel each other (Hunt, Breuker, Sadowski, & Moore, 2009; Moore & Moore, 1999). For instance, reinforcement be- tween both types of sexual selection may arise when the same trait values that are preferred by females also increase the success in maleemale competition (Berglund, Bisazza, & Pilastro, 1996; Hunt et al., 2009; Kirkpatrick & Ryan, 1991; Kokko, 2001; Mead & Arnold, 2004). On the other hand, inter- and intrasexual selection could act differently on a given sexual trait if females prefer to mate with males that do not have the highest intrasexual competitive abilities (Arnqvist, 1992; Holland & Rice, 1998; Hunt et al., 2009; Mead & Arnold, 2004). Therefore, the combined outcome of sexual selec- tion on a given sexual trait will depend on the interaction between the strength, direction and form of both inter- and intrasexual se- lection, the existence of balancing selection being a possible outcome. Determining both female choice and maleemale competition and how they interact with each other is necessary to gain a better understanding of how sexual selection acts on sexual traits (Hunt et al., 2009; Moore & Moore, 1999). Anurans and insects communicating by means of acoustic sig- nals have been widely used as model species to study the evolution of sexual communication. This is because they use relatively simple acoustic signals that can be synthesized according to the parame- ters of the population distribution, a useful characteristic when exposed to controlled experimental procedures (Gerhardt & Huber, 2002; Wells & Schwartz, 2006). Males of these taxa generally produce advertisement calls, a type of signal involved in female attraction and male spacing (Gerhardt & Huber, 2002; Wells & * Correspondence: F. N. Moreno-G omez, Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Avenida Rector Eduardo Morales Miranda, Edificio Pugín, Valdivia, Chile. E-mail address: f.n.moreno.gomez@gmail.com (F. N. Moreno-G omez). Contents lists available at ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav http://dx.doi.org/10.1016/j.anbehav.2015.03.010 0003-3472/© 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Animal Behaviour 104 (2015) 79e86