Plasticity and inter-population variability in physiological and life-history traits of the mussel Mytilus chilensis: A reciprocal transplant experiment Sebastián J.A. Osores a , Nelson A. Lagos b , Valeska San Martín d , Patricio H. Manríquez c , Cristian A. Vargas d , Rodrigo Torres e , Jorge M. Navarro f,i , M. Josefina Poupin a,j , Gonzalo S. Saldías h , &, Marco A. Lardies g, ⁎ a Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile. b Laboratorio de Ecología y Cambio Climático, Centro de Investigación e Innovación para el Cambio Climatico, Universidad Santo Tomas, Ejército 146, Santiago, Chile. c Laboratorio de Ecología y Conducta de la Ontogenia Temprana (LECOT), Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile. d Laboratorio de Funcionamiento de Ecosistemas Acuáticos (LAFE), Unidad de Sistemas Acuáticos, Centro de Ciencias Ambientales EULA Chile, Universidad de Concepción, Concepción, Chile e Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile f Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile. g Facultad de Artes Liberales, Universidad Adolfo Ibáñez, Santiago, Chile h College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, USA i Centro FONDAP de Investigación en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Valdivia, Chile j Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile abstract article info Article history: Received 10 August 2016 Received in revised form 25 January 2017 Accepted 6 February 2017 Available online 11 February 2017 Geographically widespread species must cope with environmental differences between habitats. Information concerning geographic variations in response to climate variability is critical because many morphological, life- history and physiological traits show variation across space. Reciprocal transplant experiments have shown to be relevant to evaluate the role of phenotypic plasticity and potential local adaptation in ecophysiological re- sponses when coping with environmental variability. In this study, we characterize through reciprocal transplant experiments the reaction norms of morphological, biochemical, physiological and life-history traits between two intertidal populations of the socioeconomically important mussel Mytilus chilensis, inhabiting contrasting local environments (estuarine vs coastal habitats). We found a gradient in phenotypic plasticity with plastic trait re- sponses in metabolic, ingestion and clearance rates, and in HsP 70 gene expression, and some traits with responses more canalized as growth and calcification rates. This emphasizes that responses not only vary across different local populations but also in different traits in M. chilensis, thus it is difficult to establish an overall trend of the responses at integrated organismal level. Moreover, the synergistic interaction of factors such as salinity and car- bonate system parameters evaluated make it necessary to study the response at the population level with em- phasis on benthic species important in aquaculture. Finally, field studies such as this one are useful for documenting the patterns of traits variation that occur in nature, identifying possible causes of such variation, and generating testable hypotheses for future controlled experiments. © 2017 Elsevier B.V. All rights reserved. Keywords: Salinity Ocean acidification Estuaries Heat shock protein Ingestion rate Metabolism Calcification Aquaculture 1. Introduction Geographically widespread species must cope with environmental differences between habitats. This ability may be achieved by genetic differentiation, phenotypic flexibility and/or local adaptation (Blanckenhorn, 1997; Lardies and Bozinovic, 2008; Lardies et al., 2011; Gaitán-Espitia et al., 2014). Information concerning geographical varia- tions in response to ocean acidification (OA), salinity and temperature are critical because many morphological, life-history and metabolic traits show variation across space (Lardies and Bozinovic, 2008; Aguilera et al., 2013; Lardies et al., 2014); an issue often attributed to or- ganismal adaptation over environmental gradients or ecological transi- tions (Miner et al., 2005). It is broadly accepted that to evaluate evolutionary changes, popula- tions within species should be compared as well as individuals within breeding populations. As a consequence, little attention has been paid to interpopulation variation despite its potential use as an approach to study changes in performance between local environments (Angilletta et al., 2002; Dupont and Thorndyke, 2009; Ramajo et al., 2016). The nat- ural variability in eco-physiological traits between populations may Journal of Experimental Marine Biology and Ecology 490 (2017) 1–12 ⁎ Corresponding author at: Facultad de Artes Liberales & Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibañez, Diagonal Las Torres 2640, Peñalolen, Santiago, Chile. E-mail address: marco.lardies@uai.cl (M.A. Lardies). http://dx.doi.org/10.1016/j.jembe.2017.02.005 0022-0981/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Experimental Marine Biology and Ecology journal homepage: www.elsevier.com/locate/jembe