Predator size, prey size, and dietary niche breadth relationships in marine predators

• Published in: Ecology (Durham) 2009-07, Vol.90 (7), p.2014-2019
• Main Author: Costa, Gabriel C
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; aquatic organisms; Average linear density; Biological and medical sciences; Biological taxonomies; Body size; Body Size - physiology; Datasets; Diet; Ecological niches; Ecology; Ecosystem; Food; Food chains; foraging; Fundamental and applied biological sciences. Psychology; General aspects; macroecology; Marine ecology; marine predators; meta-analysis; niche breadth; Oceans and Seas; optimal foraging; phylogenetic contrast; Phylogenetics; Predation; predator; predator-prey relationships; Predators; Predatory Behavior - physiology; prey size; Sea water ecosystems; Species Specificity; Statistical variance; Synecology
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/08-1150.1

Based on geographical and home range sizes, physiology, and gape limitation, a positive relationship between predator size and diet breadth is expected. Alternatively, larger predators might avoid smaller prey; in this case no relationship would be found. Here, I used a large data set on the diets of marine predators to describe and identify mechanisms responsible for the relationships among predator body size, diet breadth, and the mean, minimum, maximum, and variance of prey size. I found no relationship between predator size and diet breadth. Mean, minimum, maximum, and variance of prey size were all positively associated with predator size. I found that larger predators increase their minimum and maximum prey size with similar slopes, which explains the lack of relationship between predator size and diet breadth. The results support predictions of the hypothesis that optimal foraging is the main factor constraining the shape of the relationships among predator size, prey size, and diet breadth. Future research should focus on examining the relationship between body size and the breadth of different niche axis across different groups of organisms to assess whether a positive relationship between body size and niche breadth is a general rule in macroecology.