Adaptive maternal investment in the wild? Links between maternal growth trajectory and offspring size, growth, and survival in contrasting environments

• Published in: The American Naturalist
• Main Authors: Burton, Tim, Rollinson, Njal, McKelvey, Simon, Stewart, David C., Armstrong, John D., Metcalfe, Neil B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Chicago Press 2020
• Subjects: Atlantic salmon; Salmo salar
• Online Access: https://eprints.gla.ac.uk/197299/; https://eprints.gla.ac.uk/197299/7/197299.pdf

Life history theory predicts that investment per offspring should correlate negatively with the quality of environment offspring are anticipated to encounter; parents may use their own experience as juveniles to predict this environment and may modulate offspring traits such as growth capacity as well as initial size. We manipulated nutrient levels in the juvenile habitat of wild Atlantic salmon Salmo salar to investigate the hypothesis that the egg size maximizing juvenile growth and survival depends on environmental quality. We also tested whether offspring traits were related to parental growth trajectory. Mothers that grew fast when young produced more, smaller offspring than mothers that had grown slowly to reach the same size. Despite their size disadvantage, offspring of faster-growing mothers grew faster than those of slow-growing mothers in all environments, counter to the expectation that they would be competitively disadvantaged. However, they had lower relative survival in environments where the density of older predatory/competitor fish was relatively high. These links between maternal (but not paternal) growth trajectory and offspring survival rate were independent of egg size, underscoring that mothers may be adjusting egg traits other than size to suit the anticipated environment faced by their offspring.