What are “death-assemblages”?

Death-assemblages are natural accumulations of skeletal remains that provide valuable snapshots of past communities.  We combine modern, historical, and fossil death-assemblages with modern and historical biodiversity surveys to reconstruct how terrestrial vertebrate species and their communities have changed through time.  To date our research focuses primarily on small mammals.

Active Research Areas:

Do the Dead Lie?  Reliability of Ecological Data from Skeletal Remains

To confidently interpret ecological information captured in death-assemblages, one must assess the magnitude and direction of biologic and taphonomic bias.  We approach this question using a live-dead comparative approach: how closely do death-assemblages reflect the composition and structure of the living community?  Does the selectivity of predators (e.g. raptors) alter the ecological signal recorded in the remains of their prey?  To what degree are skeletal remains spatially and temporally averaged?

Species Dynamics in Response to Holocene Environmental Change

Establishing pre-19th and 20th century dynamic baseline conditions for terrestrial species and communities is critical for predicting how these species and communities are likely to respond to future climate and land-use scenarios.

By reconstructing species abundances back through the Holocene, and comparing these records with paleoclimate reconstructions and archaeological records, we can ask what abiotic and biotic drivers are important in shaping past community responses to environmental change?  What makes some species thrive and other species suffer under conditions of climate warming?

We are also evaluating the degree to which resource use patterns have shifted through time using stable isotopes.  How stable are the isotopic niches of species through time?  Do they expand, contract, or shift in response to climatic changes?

Shifting Baselines in Desert Communities

Taking a historical perspective on ecology also helps us evaluate the degree to which the last century of anthropogenic impacts has pushed modern systems beyond their range of natural variability.  We do this using historical re-surveys, live-dead discordance analyses, and stable isotopes. 

By combining these approaches we can ask how individual species and aggregate properties of entire communities have responded to climate warming and past land-use.  How robust are the community properties of richness, evenness, biomass, and energy consumption to underlying shifts in species composition?  Do different legacies of past land-use leave distinct traces in live-dead discordance?  How has the introduction of invasive plant species (e.g. cheatgrass) impacted resource use patterns and abundance dynamics?

Check out our publications page to learn more!