Abstract
Phenotypic plasticity can be viewed as the first level of defense of organism homeostasis against environmental stress and therefore represents the potential to deal with rapid environmental changes. Transitions between low complexity, artificial environments and complex, natural habitats can promote phenotypic plasticity. Here, we conducted an experimental introduction with juvenile brown trout to evaluate the plasticity of shape in response to a transition between contrasting environments. We released 202 juvenile trout reared under hatchery conditions in a natural stream and analyzed changes in shape and morphological variability after 5 months. A geometric morphometrics approach based on 14 landmarks was used to compare changes in body shape for 37 fish recaptured at the end of the experiment. A similar number of hatchery and wild fish caught at the receptor stream were used as controls for shape in the two environments. After 5‐months, fish showed significant change in shape, shifting from elongated to robust shapes, and affecting to the relative position of the caudal peduncle. These new shapes were closer to wild than to the hatchery shapes, suggesting a process of rapid phenotype change. Moreover, these changes were concomitant with a marked increase in morphological variability. Our results support the hypothesis that phenotypic plasticity is a major potential for adjustment to environmental change but not the idea that shape can be constrained by initial shapes. We confirmed the “increased” variance hypothesis and phenotype convergence with wild morphs. This has important implications because stresses the role of phenotypic plasticity as a buffer that allows organisms to cope with important environmental discontinuities at time scales that preclude the onset of adaptive adjustments. We suggest that environmental conditioning and shape plasticity can overcome both reduced morphological diversity and phenotype uncoupling with habitat characteristics resulting from initial rearing in low complexity artificial environments.
Highlights
A central question in forecasting the viability of organisms and populations to rapid environmental change is whether phenotypic plasticity can mediate the adjustment to the new conditions before an evolutionary response is attained
Phenotypic plasticity can act as a buffer for environmental variation that, otherwise, might promote local adaptation
Local populations and ecotypes often differ in body shape because of genetics (Hard, Winans, & Richardson, 1999; Nicieza, 1995; Taylor, 1991), environmental conditioning (Langerhans, Layman, Langerhans, & Dewitt, 2003; Svanbäck & Eklöv, 2002), or both (Keeley, Parkinson, & Taylor, 2007; Marcil, Swain, & Hutchings, 2006)
Summary
A central question in forecasting the viability of organisms and populations to rapid environmental change is whether phenotypic plasticity can mediate the adjustment to the new conditions before an evolutionary response is attained. The morphological changes experienced by fish reared in artificial environments can have negative effects for survival in the wild (Bohlin et al, 2002; Von Cramon-Taubadel et al, 2005). The effectiveness of stocking with artificially reared fish might depend on their ability to converge with the “environmental” phenotype Such convergence, mediated by phenotypic plasticity, might compensate for differences associated with genetic or environmental variation, and it can have profound implications for population reinforcement. Because fish shape can be molded by environmental conditions affecting exercise demands and swimming styles, artificial habitats are expected produce a reduced range of shapes compared to natural streams. We test two nonexclusive hypotheses: (1) the change in shape will be consistent with the shape configurations of wild fish (convergence hypothesis), and (2) the phenotypic change results from the spread of initial shape configurations in response to dispersion of fish across a greater variety of microhabitats (increased variance hypothesis)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
