1. Using Genetic Modeling of Sedimentary Parameters to Predict Species’ Geographic Range Shifts in Response to Environmental Change
Alycia L. Stigall, Department of Geological Sciences, Ohio University
This project aims to adapt methods of ecological niche modeling methods to reconstruct species’ niches and predict geographic ranges of fossil species based on sedimentary parameters. Developing a quantitative method specifically based on sedimentary variables (observable in the field or thin-section) to predict geographic occurrences of 1 2
species (and the potential for the converse), has the potential to improve biostratigraphic accuracy by providing a basis to distinguish
actual evolutionary (e.g. temporal) versus environmental absence of taxa.
For this project, the Late Ordovician rocks in the Cincinnati, Ohio region are analyzed (Fig. 1). Three depositional sequences have been examined. Timelines within these units were established by identifying and correlating nine parasequences across the study area (Fig. 2). Sedimentology and articulated brachiopod species occurrences for each time slice have been constrained through field analysis at multiple sites across the basin. Two methods, GARP and Maxent, have been used to model species niches and geographic ranges (bottom panel). Both are methods developed for modern taxa that appear to produce highly accurate models when used with fossil data.
Analysis of niche models indicates that species niches may be more stable during intervals of biotic and environmental change than during intervals of relative stability. This result provides critical insight into how modern species may react to current global changes.
Predicted range of Hebertella occidentalis
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