Changing Feeding Levels Reveal Plasticity in Elasmobranch Life History Strategies

Area of Science:

• Marine biology
• Ecology
• Evolutionary biology

Background:

• Life history strategies are crucial for understanding species' adaptations and conservation needs.
• Elasmobranchs (sharks and rays) exhibit diverse life history traits influenced by phylogeny, environment, and energy budgets.

Purpose of the Study:

• To analyze and structure elasmobranch life history strategies based on feeding levels and environmental contrasts.
• To investigate the plasticity of these strategies and their predictive power for population performance and conservation status.

Main Methods:

• Principal components analysis (PCA) was used to summarize life history traits of 151 elasmobranch species.
• Species were analyzed across two contrasting feeding levels representing different environments.

Main Results:

• Two principal axes, reproductive output and generation turnover, define elasmobranch life history strategies.
• Life history strategies demonstrated plasticity, with increased feeding levels leading to higher reproductive output.
• While both axes predicted population performance, population growth rate did not reliably indicate demographic resilience.

Conclusions:

• Elasmobranch life history strategies are not fixed and exhibit significant plasticity.
• Extrapolating life history strategies between environments is cautioned against when predicting responses to climate change, perturbations, or overexploitation.