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Significant research progress has been made during the first fifteen months of this research grant.   Specifically, over 60 days of field work was conducted, ten meeting presentations were given, and two manuscripts were submitted related to niche modeling of fossil taxa.  Three additional abstracts have already been submitted for meetings during the second grant year.   Three master’s students (Nicole Dudei, Robert Swisher, and Brad Walls) were partially supported during the grant period.  Specifically, the grant provided salary for summer and one academic quarter for each student.  All three students completed MS theses and five peer-reviewed articles are expected to eventually result from this work.  The key research marks accomplished are listed in more detail below.

Extensive field work was conducted in the Cincinnati, Ohio region of southwest Ohio, southeast Indiana, and northern Kentucky during the summer and fall of 2008.  The primary goals of the field investigation were (1) create detailed stratigraphic sections of as many sites as possible within the C3, C4, and C5 sequences to provide the base data for environmental modeling and sequence stratigraphic interpretation and (2) identify all brachiopod species at each outcrop.   Each of the three graduate students were assigned to coordinate the data collection and analysis for one sequence (Walls: C3, Dudei: C4, Swisher: C5).  Over 30 field locations were investigated. 

Following field work, parasequences were identified within each of the three sequences of interest to provide timelines for regional correlation and for niche modeling analysis.  Three parasequences were identified in each of the C3 and C4 sequences and nine parasequences were identified in the C5 sequence.  This represents the first sequence stratigraphic hypothesis for upper Cincinnatian rocks at a finer scale than depositional sequence.  Parasequence boundaries were used to divide each sequence into three time slices.  Once outcrops were correlated, sedimentary data for 5 variables (inferred water depth, limestone bedding style, limestone bedding thickness, sedimentary structures, biofacies, and percent shale) were coded.  Contour maps of environmental distribution were constructed from this data. 

The environmental data was paired with the species occurrence data set previously assembled by the PI to model the ranges of articulate brachiopod species.  A total of eight, ten, and sixteen species were modeled in each of the C3, C4, and C5 sequences, respectively.  Preliminary geographic range analyses were conducted and presented in two posters and one oral presentation at the Geological Society of America’s fall meeting in Houston, TX.  Following this, all models were refined through data improvement including critical analysis of sedimentary variables, addition of new high quality species occurrence data, and fine tuning of the study area (modeling over a polygon rather than rectangular surface).  Analyses of refined models included assessment of change in area of geographic range through time and preliminary analyses of niche conservatism in geologic time.  The results of these analyses were written up by each coordinating student for the MS thesis and presented in three oral presentations at the North American Paleontological Convention in Cincinnati, OH in June 2009.  The PI is currently in the process of converting thesis text to publishable manuscripts.  Five manuscripts will eventually be produced from the three theses.  One has been submitted and the other four are in revision with the PI at this time.

Results from the geographic ranges predicted through environmental niche modeling demonstrated high levels of statistical significance.  A secondary analysis in which the accuracy of the niche models was directly tested by secondary field collection of species occurrence data from 18 new field sites indicated that 19 of the 22 geographic range models produced for the C3 sequence were statistically accurate.  Of the 140 individual species occurrences assessed, 60.8% were accurately predicted, 9.2% exhibited under prediction, and 30% exhibited over prediction. 19 of the original 22 GARP models were demonstrated to be statistically significant based on field validation. Accurate results were more common for species modeled from the greatest number of species occurrence points. Species models that were demonstrated to be insignificant were for eurytopic species or those for which taxonomic affinities are unclear.

Additional work on niche modeling during the first year of the grant period included work on completing ongoing work on the use of niche modeling to assess biogeographic patterns of Miocene horses.  The abstracts on this topic were presented, and one paper on this topic is now accepted for publication.

Research during the second year of the grant period will focus on improving accuracy of geographic ranges estimated from niche models of Cincinnatian brachiopods.  One new MS student, Richard Malizia, will begin a thesis project that attempts to combine the dataset for the C3, C4, and C5 sequences to determine whether species can be modeled across all 9 of the previously identified time slices.    This project will involve additional weeks of field work in the spring and summer of 2010.  Revision of theses into publishable papers will also continue.  A minimum of four additional manuscripts are expected to be submitted this year.   Furthermore, presentations will be given at the annual GSA meeting in Portland, OR and the International Brachiopod Congress in Melbourne, Australia.

Students supported, theses directed:

Nicole Dudei, MS Geological Sciences, August 2009, The impact of the Richmondian Invasion on paleobiogeographic distribution of taxa in the Late Ordovician C4 sequence (Richmondian Stage, Cincinnati, Ohio) including a comparison of range reconstruction methods

Robert Swisher, MS Geological Sciences, August 2009, Paleobiogeographical and evolutionary analysis of Late Ordovician C5 sequence brachiopod species with special reference to rhynchonellid taxa

Bradley Walls, MS Geological Sciences, June 2009, Quantitative paleobiogeography of Maysvillian (Late Ordovician) brachiopod species on the Cincinnati Arch: A test of niche modeling methods for paleobiogeographic reconstruction

Richard Malizia, MS Geological Sciences, started September 2009: Testing niche evolution in Late Ordovician brachiopods