Increase in evenness and sampled alpha diversity through the Phanerozoic: Comparison of early Paleozoic and Cenozoic marine fossil assemblages

Research Article| April 01, 2002 Increase in evenness and sampled alpha diversity through the Phanerozoic: Comparison of early Paleozoic and Cenozoic marine fossil assemblages Matthew G. Powell; Matthew G. Powell 1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA Search for other works by this author on: GSW Google Scholar Michal Kowalewski Michal Kowalewski 2Department of Geological Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Matthew G. Powell 1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland 21218, USA Michal Kowalewski 2Department of Geological Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA Publisher: Geological Society of America Received: 27 Jul 2001 Revision Received: 21 Nov 2001 Accepted: 21 Dec 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (4): 331–334. https://doi.org/10.1130/0091-7613(2002)030<0331:IIEASA>2.0.CO;2 Article history Received: 27 Jul 2001 Revision Received: 21 Nov 2001 Accepted: 21 Dec 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Matthew G. Powell, Michal Kowalewski; Increase in evenness and sampled alpha diversity through the Phanerozoic: Comparison of early Paleozoic and Cenozoic marine fossil assemblages. Geology 2002;; 30 (4): 331–334. doi: https://doi.org/10.1130/0091-7613(2002)030<0331:IIEASA>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Existing reconstructions of the Phanerozoic history of biological diversity are based on occurrences of taxa and do not include abundance data. This study examines trends in the relative abundance of taxa and provides a new perspective on the Phanerozoic history of marine diversity. We compared the abundance versus diversity (AD) structure of early Paleozoic and Cenozoic samples of marine benthic genera compiled from the literature. The sample-standardized results indicate (1) a two-and-a-half–fold increase in sampled alpha diversity but, concurrently, (2) an increase in the evenness of fossil samples through time. The observed evenness trend may be due to taphonomic biases, time-averaging trends, differences in sampling techniques, or real changes in the structure of marine communities. Regardless of the underlying factors, the results indicate that the evenness of fossil samples increased through the Phanerozoic, largely owing to a decrease in the relative abundance of the most common taxa. Because sampling fossil sites of different evenness can result in different estimates of species richness even if their total alpha diversity is the same, the observed changes in evenness may have contributed to the Phanerozoic increase in sampled alpha diversity and, at least in part, to the increase in global diversity. The incorporation of taxon abundance data into future studies should produce a more robust, perhaps even different, interpretation of the Phanerozoic history of diversity. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.