Changing feeding levels reveal plasticity in elasmobranch life history strategies

Abstract

AbstractLife history strategies are shaped by phylogeny, environmental conditions and individual energy budgets, and have implications for population performance. Here, we used an approach that merges demography with energy budget theory to structure life history traits of 151 elasmobranch species into life history strategies for two contrasting feeding levels. We assessed how phylogeny and habitat impacted life history strategies, and tested if these strategies predict population performance and conservation status. Elasmobranch life history strategies are structured along the fast-slow continuum and reproductive strategy axes. However, species’ positions in this life history space were not fixed, but instead moved in an anticlockwise ‘whirlpool’ manner along the two axes in response to an increase in feeding level. We also found that population growth rate does not necessarily inform on a species demographic resilience. Finally, only at the higher feeding level does the fast-slow continuum predict IUCN conservation status, with the slowest species at the highest risk of extinction. Our analyses reveal plasticity in species life history strategies, and warn against extrapolating the fast-slow continuum and reproductive strategy framework from one environment to another when predicting a species’ response to (climate) change, perturbations, and, particularly in case of elasmobranchs, (over)exploitation.