Fossil samples archive functional diversity in marine ecosystems: An empirical test from a present-day coastal environment.

The fossil record of functional diversity is increasingly used to study ecosystem evolution, extinction recovery, and factors affecting long-term trends in biodiversity. In addition, the youngest fossil record (late Quaternary) can provide insights into the natural range of functional variability of present-day ecosystems, providing a historical framework for conservation and restoration. However, the reliability of common functional diversity measures derived from fossils is uncertain. If fossils yield reasonable estimates of functional diversity, paleontological data could provide information on ecological attributes and trophic structure in past ecosystems allowing for temporally scalable assessments of ecological and evolutionary processes. To assess how well fossils preserve functional diversity across multiple types of marine invertebrates with varying preservation potential, we compared the live benthos (135 species from 6 phyla) with sympatric skeletal accumulations (150 species) and the predicted fossil record (112 species) for 51 coastal sites in North Carolina (USA). High functional fidelity between the live, dead, and fossil assemblages was supported by congruence in quantitative functional diversity indices (e.g., functional richness, redundancy, overredundancy, and vulnerability), overlap in multidimensional functional space, and species distributions among functional groups ( > 0.85, ≪ 0.001). Calculating vulnerability using a threshold of ≤2 species also reasonably approximated the vulnerability in the live assemblages. The results suggest that, despite differential preservation and time-averaging, functional estimates based on fossils may allow for historical assessments of ecological and evolutionary processes, including short-term community responses to human impacts as well as long-term macroevolutionary dynamics of marine ecosystems.