title: Remembrance of things past: modelling the relationship between species' abundances in living communities and death assemblages.
abstract: Accumulations of dead skeletal material are a valuable archive of past ecological conditions. However, such assemblages are not equivalent to living communities because they mix the remains of multiple generations and are altered by post-mortem processes. The abundance of a species in a death assemblage can be quantitatively modelled by successively integrating the product of an influx time series and a post-mortem loss function (a decay function with a constant half-life). In such a model, temporal mixing increases expected absolute dead abundance relative to average influx as a linear function of half-life and increases variation in absolute dead abundance values as a square-root function of half-life. Because typical abundance distributions of ecological communities are logarithmically distributed, species' differences in preservational half-life would have to be very large to substantially alter species' abundance ranks (i.e. make rare species common or vice-versa). In addition, expected dead abundances increase at a faster rate than their range of variation with increased time averaging, predicting greater consistency in the relative abundance structure of death assemblages than their parent living community.
authors.affiliation: Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA. olszewski@geos.tamu.edu
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Olszewski
mesh_terms: D044822:Biodiversity; D058448:Biota; D005580:Fossils; D008954:Models, Biological; D010163:Paleontology / Q000379:methods*