Ecological patterns in time and space

The fossil record is the only source of information on the long-term dynamics of species assemblages. Here we assess the degree of ecological stability of the epifaunal pterioid bivalve assemblage (EPBA), which is part of the Middle Devonian Hamilton fauna of New York—the type example of the pattern of coordinated stasis, in which long intervals of faunal persistence are terminated by turnover events induced by environmental change. Previous studies have used changes in abundance structure within specific biofacies as evidence for a lack of ecological stability of the Hamilton fauna. By comparing data on relative abundance, body size, and predation, indexed as the frequency of unsuccessful shell-crushing attacks, of the EPBA, we show that abundance structure varied through time, but body-size structure and predation pressure remained relatively stable. We suggest that the energetic set-up of the Hamilton fauna's food web was able to accommodate changes in species attributes, such as fluctuating prey abundances. Ecological redundancy in prey resources, adaptive foraging of shell-crushing predators (arising from predator behavioral or adaptive switching in prey selection in response to changing prey abundances), and allometric scaling of predator-prey interactions are discussed as potential stabilizing factors contributing to the persistence of the Hamilton fauna's EPBA. Our study underscores the value and importance of multiple lines of evidence in tests of ecological stability in the fossil record.

GSA Today

Tracking biodiversity changes based on body fossils through geologic time became one of the main objectives of paleontology in the 1980s. Trace fossils represent an alternative record to evaluate secular changes in diversity. A quantitative ichnologic analysis, based on a comprehensive and global data set, has been undertaken in order to evaluate temporal trends in diversity of bioturbation and bioerosion structures. The results of this study indicate that the three main marine evolutionary radiations (Cambrian Explosion, Great Ordovician Biodiversification Event, and Mesozoic Marine Revolution) detected in the body-fossil record are also expressed in the trace-fossil record. Analysis of ichnodiversity trajectories in marine environments supports Sepkoski's logistic model, which was originally based on analysis of marine body fossils. The tracefossil record of continental environments suggests variable rates of increases in ichnodiversity, with major radiations in the Ludlow-Early Devonian, Cisuralian, Early Jurassic, Late Cretaceous, and Eocene, and slower increases or plateaus in between these periods. Our study indicates that ichnologic information represents an independent line of evidence that yields valuable insights to evaluate paleobiologic megatrends.

Springer eBooks, 2012

Conserving biodiversity in the face of expanding human degradation of ecosystems is facilitated by understanding the natural state of communities prior to the impact of anthropogenic disruptions. Reconstructing communities and ecosystems as they existed in the past requires data from the fossil record on their species composition, richness, and abundance. Fossil data are potentially different from data collected from living communities in their spatial, temporal, and taxonomic scales and these differences must be understood so that accurate comparisons can be made between past and present states of living communities. Fifty-four long-term ecological studies of a wide range of taxon groups (mammals, invertebrates, plants, corals) and habitat types (marine, terrestrial, freshwater) were surveyed from the published ecological literature to determine the range of spatial, temporal and taxonomic scales at which data are commonly collected in ecological research. Long-term ecological studies encompass spatial scales from 50 m 2 to 100,000 km 2 and temporal scales from 5 to 100 years. Most studies resolve taxa to the species level and count individuals, although plant and coral studies sometimes quantify species by percent cover. All taxon groups and habitat types were studied across a wide range of spatial and temporal scales. Whether or not data from fossils can be collected and analysed at scales comparable to data from living communities depends on the type of organism, as well as the taphonomic circumstances of preservation, accumulation and deposition. Marine invertebrates can be sampled at comparable spatial and taxonomic scales to living invertebrates, but time averaging degrades the temporal resolution of the fossil deposits. Vertebrate fossils provide data at comparable taxonomic scales with some reduction in spatial and temporal resolution relative to live data. Plant fossils and pollen are capable of being sampled at temporal resolutions comparable to modern

Journal of Biogeography, 2013

Journal of Biogeography, 40, 813-820) disagrees with the methods or interpretations in two of our recent papers. In addition, the authors open a debate on biogeographical concepts, and present an alternative philosophy for biogeographical research in the context of their recently described biogeographical subregion called 'Pandora'. We disagree with their approach and conclusions, and comment on several issues related to our differing conceptual approaches for biogeographical research; namely, our use of molecular phylogenetic analyses, including time estimates; and Parenti & Ebach's reliance on taxon/general area cladograms. Finally, we re-examine their 'tests' supporting the existence of 'Pandora'.

American Journal of Physical Anthropology, 1993

From Evolution to Geobiology: Research Questions Driving Paleontology at the Start of a New Century. The Paleontological Society Papers, 2008

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