FOSSILS TRACK SPATIAL BIODIVERSITY PATTERNS IN MARINE BENTHIC COMMUNITIES

The utility of death assemblages for estimating spatial biodiversity patterns was evaluated here by comparing live communities and their sympatric death assemblages at 52 sites in coastal North Carolina (USA). Spatial heterogeneity in diversity (beta variance [BV]) observed in the entire macro-benthic community (BV=0.64­) was closely approximated by the beta variance estimated using only live mollusks (BV=0.65), highly preservable (thick-shelled) mollusks (BV=0.65), sympatric death assemblages (BV=0.72), and dead thick-shelled mollusks (BV=0.73). Consistently, bathymetric diversity gradients (beta gradient [BG]) observed for the entire macro-benthos were also tracked tightly by live mollusks, robust mollusks, death assemblages, and dead robust mollusks. These results indicate that fossil and death assemblages, even when limited to most ubiquitous subsets such as mollusks, can yield reliable data for estimating spatial biodiversity patterns. Fossils, and mollusk shells in particular, may represent a reliable strategy for examining spatial variation in biodiversity over evolutionary, archeological, and historical ecological time scales.