Journal Article

Metabolic asymmetry and the global diversity of marine predators

Kaschner, Kristin, Alfaro, Brian, Wilson, Adam M., Maitner, Brian S., Wearing, Helen J., Record, Sydne, Brown, James H., Tittensor, Derek P., Dell, Anthony I., Grady, John M., Zarnetske, Phoebe L., Winter, Ara S., Smith, Felisa A.

2019

Overview

Generally, biodiversity is higher in the tropics than at the poles. This pattern is present across taxa as diverse as plants and insects. Marine mammals and birds buck this trend, however, with more species and more individuals occurring at the poles than at the equator. Grady et al. asked why this is (see the Perspective by Pyenson). They analyzed a comprehensive dataset of nearly 1000 species of shark, fish, reptiles, mammals, and birds. They found that predation on ectothermic (“cold-blooded”) prey is easier where waters are colder, which generates a larger resource base for large endothermic (“warm-blooded”) predators in polar regions. Science , this issue p. eaat4220 ; see also p. 338 Marine mammal and bird diversity is highest in polar regions, owing to the availability of cold, slow prey. Species richness of marine mammals and birds is highest in cold, temperate seas—a conspicuous exception to the general latitudinal gradient of decreasing diversity from the tropics to the poles. We compiled a comprehensive dataset for 998 species of sharks, fish, reptiles, mammals, and birds to identify and quantify inverse latitudinal gradients in diversity, and derived a theory to explain these patterns. We found that richness, phylogenetic diversity, and abundance of marine predators diverge systematically with thermoregulatory strategy and water temperature, reflecting metabolic differences between endotherms and ectotherms that drive trophic and competitive interactions. Spatial patterns of foraging support theoretical predictions, with total prey consumption by mammals increasing by a factor of 80 from the equator to the poles after controlling for productivity.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Abundance / Ambient temperature / Animals / Aquatic reptiles / Biodiversity / Biological evolution / Bird populations / Birds / Birds - physiology / Body temperature / Body Temperature Regulation / Climate / Coastal ecology / Coastal environments / Cold / Cold water / Datasets / Eye movements / Fishes - physiology / Flicker / Flicker fusion / Food availability / Food Chain / Food chains / Food consumption / Food production / Food webs / Foraging behavior / Habitats / Insects / Latitude / Mammals - physiology / Marine fish / Marine mammals / Metabolic response / Metabolism / Models, Biological / Motor Reactions / Ocean temperature / Oceans / Oceans and Seas / Phylogenetics / Phylogeny / Physiology / Polar environments / Poles / Predation / Predators / Predatory Behavior / Predictions / Prey / Productivity / Reptiles / Reptiles - physiology / RESEARCH ARTICLE SUMMARY / Saccadic eye movements / Sharks / Spatial distribution / Species diversity / Species richness / Strategy / Swimming / Temperature / Temperature effects / Theory / Thermal stress / Thermoregulation / Tropical environments / Vertebrates / Water / Water temperature