CSIC Seville Spain

1 Introduction Environmental factors influence the growth and development of animals during early life stages, often with lasting effects later in life (Gomez-Mestre et al. 2010; Bouchard et al. 2016). To cope with environmental heterogeneity, phenotypic plasticity serves as a central adaptive mechanism by which organisms adjust their morphology, physiology, and behaviour, thereby enhancing fitness across diverse ecological contexts (Pigliucci 2001; West-Eberhard 2003).

1 Introduction Understanding the ecological and evolutionary drivers of species specialisation is crucial for elucidating the mechanisms that give rise to the diverse ecological strategies observed in biological communities worldwide. Specialisation, defined as the narrowness of the sets of environments or resources a species can exploit (Devictor et al. 2010), constitutes a core concept to understand biological adaptations (Sexton et al. 2017), predict biological invasions (Daly et al.

1 Introduction Human-driven activities expose wildlife to a myriad of stressors, including altered temperatures, habitat loss, and pollution (Lee et al. 2023). These conditions have the potential to impair vital processes such as metabolism, growth, development, or reproduction, which finally can compromise organismal health and survival (Román-Palacios and Wiens 2020; Sheridan and Bickford 2011).