Assessing feeding preferences of a consumer guild: partitioning variation among versus within species

Interspecific variation in resource use is critical to understanding species diversity, coexistence, and ecosystem functioning. A growing body of research describes analogous intraspecific variation and its potential importance for population dynamics and community outcomes. However, the magnitude of intraspecific variation relative to interspecific variation in key dimensions of consumer-resource interactions remains unknown, and is critical for understanding the importance of this variation for population and community processes. In this study, we examine feeding preference through repeated laboratory choice feeding assays of 444 wild-caught individuals of eight invertebrate grazer species on rocky reefs in northern California, USA. Between-species variation accounted for 25-33% of the total variation in preference for the preferred resource, while between-individual variation accounted for 4-5% of total variation. For two of the eight species, between-individual variation was signifi...