Life history mediates large-scale population ecology in marine benthic taxa

Abstract

Progress in marine biodiversity research requires a suite of approaches to understand processes occurring across a broad range of spatial scales. Macroecology provides a useful frame- work for understanding how local- and regional-scale processes interact, and comparative analyses of residual variation around macroecological relationships offer a promising route to better under- stand how the biological and ecological traits of individual species influence large-scale patterns in diversity. We combined data on the distribution and abundance of 575 North Sea macrobenthic species with a new species-level biological traits database to determine the effects of life history on the relationship between local population density and regional occupancy. We found the strongest effects were for body size: for a given local population density, larger-bodied species tended to be more widely distributed than smaller-bodied species (controlling for taxonomic affinities between species). This indicates a broad trend for large-bodied species to have relatively less aggregated distributions than smaller-bodied species, and is the first demonstration in marine systems that abun- dance-occupancy relationships are mediated by body size. We suggest that this effect is most likely due to the interrelationships between body size and other life-history traits that influence the large- scale dispersal of individuals, in particular, mode of larval development and adult migratory habit. The ability of a single life-history trait to capture this variation in spatial structure suggests that our approach could relatively easily be applied to more extensive marine data sets in the future.