Salamanders breeding in subterranean habitats: local adaptations or behavioural plasticity? R. Manenti 1 & G. F. Ficetola 2 1 Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy 2 DISAT, Università degli Studi di Milano – Bicocca. Milano, Italy Keywords cave; Salamandra salamandra; underground; ecology; predation performance; biospeleology. Correspondence Raoul Manenti, Diupartimento di Bioscienze, Università degli Studi di Milano, Via Celoria, 26, Milano, 20133, Italy. Email: raoul.manenti@unimi.it Editor: Mark-Oliver Rödel Received 14 May 2012; revised 14 September 2012; accepted 14 September 2012 doi:10.1111/j.1469-7998.2012.00976.x Abstract The exploitation of novel habitats requires the expression of specific behaviours. This may occur through both behavioural plasticity and local adaptations, but assessing the relative role of these processes is challenging. Animals colonizing underground environments are exposed to strong selective pressure: epigeous species using caves during one or more phases of their life cycles can help to understand mechanisms allowing cave exploitation. The fire salamander (Sala- mandra salamandra) may breed both in cave springs and in epigeous streams. We compared predation performance of larvae from cave and stream populations, and assessed whether local adaptations or behavioural plasticity (or both) improve predation in underground environments. We performed a behavioural experiment about prey detection and capture. We collected larvae from both caves and streams, and reared them under contrasting conditions: underground and outdoor. In the darkness, we tested two measures of predation performance of larvae: time of head turning towards the prey and frequency of prey capturing. We used an information-theoretic approach to assess the relative support of potential mechanisms (adaptations vs. plasticity). Both cave and stream larvae were able to detect and capture prey in the darkness. Larvae born in caves captured prey with higher success than those from streams. Acclimatization to underground condi- tions did not improve predation performance, suggesting that plasticity plays a minor role. This study indicates that the exploitation of underground environ- ments leads to behavioural local adaptations, allowing an improved predation performance in environments where prey are both scarce and difficult to detect. Introduction During the exploitation of new habitats, populations are exposed to selective pressures that may lead to evolutionary adaptations for multiple traits, such as behaviour, morphol- ogy, metabolism and physiological tolerance. Such intraspe- cific adaptations can evolve quickly, particularly when natural selection is strong, or generation time is fast (Miner et al., 2005; Steinfartz, Weitere & Tautz, 2007). On the other hand, a single genotype can generate multiple phenotypes in response to variation of abiotic and biotic conditions of environments (phenotypic plasticity; Miner et al., 2005; Gomez-Mestre, Touchon & Warkentin, 2006). Phenotypic plasticity allows a quick response to environmental conditions, may favour the colonization of heterogeneous habitats (Hawlena, Hughes & Schmitz, 2011; Peacor et al., 2011; Jourdan-Pineau, David & Crochet, 2012) and can play an important role in adaptation processes (Price et al., 2003). Although plasticity may absorb the effects of environmental variation and reduce the genetic response to selection, thus retarding evolutionary change (Gomez-Mestre & Buchholz, 2006), it may facilitate evolu- tionary diversification if environmentally induced phenotypic changes allow populations to survive or colonize different or new habitats, and thus develop independently evolving line- ages (Gianoli & Valladares, 2011; Lind & Johansson, 2011). When the new habitat strongly differs from the usual one, the emerging adaptations are expected to be particularly important (Dreiss, Guillaume & Clobert, 2009). Underground environments are extremely interesting to understand the processes allowing the exploitation of novel environments (Jugovic et al., 2011; Riesch, Plath & Schlupp, 2011). Under- ground environments differ from the epigeous ones for mul- tiple features, such as light scarcity, limited food and stability of microclimate (Culver et al., 2004). Epigeous species attempting the colonization of underground habitats are exposed to strong selective pressures that can induce dramatic phenotypic changes, and may lead to genetic adaptations favouring individual development, survival and fitness (Frie- drich et al., 2011; Riesch et al., 2011). These changes can be both morphological, such as in underground populations of the fish Astyanax fasciatus that evolved typical troglomorphic features (loss of eyes and pigmentation; Salin et al., 2010), and Journal of Zoology Journal of Zoology. Print ISSN 0952-8369 182 Journal of Zoology 289 (2013) 182–188 © 2013 The Authors. Journal of Zoology © 2013 The Zoological Society of London