Ohio University faculty will make an impact with 23 presentations at the Geological Society of America’s 125th Anniversary Annual Meeting & Exposition Oct. 27–30 in Denver.
Alycia Stigall presented ENVIRONMENTAL CHANGE AND NICHE EVOLUTION: WHICH TYPES OF CHANGE PROMOTE ADAPTIVE RESPONSE?. Stigall is Associate Professor of Geological Sciences at Ohio University and Ohio Center for Ecology and Evolutionary Studies.
Environmental change, including both biotic and abiotic change, is the primary driver of evolutionary innovation and extinction. Adaptive responses to environmental change that result in morphological divergence are concentrated during speciation events; whereas, most species exhibit morphological stability during the remainder of their existence. Understanding the mechanisms that control when a species does and does not demonstrate adaptive response is, therefore, a critical component of understanding evolutionary dynamics.
This study examines niche stability within a diverse suite of marine invertebrates that occupied a shallow marine basin centered on present day Cincinnati, OH, USA during the C3, C4, and C5 sequences of the Katian Age (Late Ordovician). Using spatial distribution modeling, we reconstructed the fundamental niche for 21 taxa of articulated brachiopods, bryozoa, trilobites, crinoids, rugose corals, bivalves, and gastropods across nine temporal intervals. The relative degree of niche stability that taxa exhibited between time slices was assessed in both geographic and environmental space.
Niche stability varied through time. During the C3 sequence, taxa exhibited niche stability (=no adaptive response) to environmental changes. Adaptive response, as indicated by increased niche evolution, became more common during and after an interbasinal invasion event, the Richmondian Invasion. Species adjusted to the increased competition by altering aspects of their niche. Notably, surviving taxa contracted their niche into a subset of their previous niche parameters. This represents an adaptive response, and it was employed most successfully by generalist taxa. Notably, patterns of niche evolution were congruent between clades, trophic group, and at both the specific and generic level. Adaptive response (stability vs. evolution) was related to the tempo, mode, or a combination of both aspects of environmental change. Biotic interactions played a key role in driving biotic divergence via habitat partitioning at the species level in this case study.
Jennifer Bauer ’14M & Alycia Stigall presented on EVOLUTION AND MORPHOLOGICAL DIFFERENTIATION OF ORDOVICIAN BRACHIOPODS EOCHONETES AND THAERODONTA. Bauer is a master’s student in the Geological Sciences program at in the College of Arts & Sciences.
The genus Thaerodonta Wang, 1949 was erected to include a suite of strophomenid brachiopods from Middle to Late Ordovician of North America characterized by small, elongate valves with hinge-line denticles and dorsal lateral septa. Thaerodonta has been synonymized with the Baltic genus Eochonetes Reed, 1917, re-recognized as a valid taxon, and subsequently synonymized again several times. The ambiguous relationship between these genera is promoted by the high degree of intraspecific variation within species and the general sympatry of “Thaerodonta” and Eochonetes sensu stricto species. Although the relationship between Thaerodonta and Eochonetes has previously been assessed based on character data, these comparisons have lacked an explicit phylogenetic framework.
In this study, we test whether Thaerodonta is an evolutionary lineage distinct from Eochonetes within a phylogenetic and morphometric context. Type and references specimens from museum collections were examined for 18 species assigned to Eochonetes or Thaearodonta. Prior to phylogenetic analysis, species validity was assessed using multivariate morphometric analysis of 9 characters. Approximately forty internal and external morphological characters were examined for each species. Both discrete and continuous characters were used. Continuous characters states were differentiated through morphometric analysis and coded as qualitative states. Species-level phylogenetic hyoptheses were generated using both parsimony and Bayesian analysis.
The resulting well-resolved phylogenetic topologies support the differentiation of Eochonetes and Thaerodonta as discrete evolutionary lineages. The monophyly of Thaerodonta is supported by multiple synapomorphies. These results indicate the importance of generic and species level characters in examining evolutionary differentiation. The trends in morphological evolution within these lineages also highlight the importance of biogeography as a driver of evolutionary patterns.
Hannah-Maria Brame ’13M, Alycia Stigall, & Jennifer Bauer ’14M presented on CREATING AN ONLINE INVERTEBRATE PALEONTOLOGY MUSEUM: TURNING FOSSILS INTO DIGITAL DATA. Brame and Bauer are master’s students in the Geological Science program in the College of Arts & Sciences.
Museum collections with high-resolution stratigraphic and geographic data have the potential to provide large amounts of data for quantitative paleontological and biogeographical analyses. Recent initiatives have focused on databasing and georeferencing these collections in an effort to improve the quality and availability of historical paleontological data. In collaboration with the NSF funded Paleoniches-TCN, the Ohio University Invertebrate Paleontology lab has built a high quality museum collection and digital database of Cincinnatian (Late Ordovician) fossils from Ohio, Kentucky, and Indiana and begun development of interactive online digital atlases of Ordovician species. The unique opportunity of building a museum collection from scratch enabled the deliberate development and digital curation of this collection for the specific purpose of facilitating quantitative applications and data accessibility.
Named for its primary collector, the Jack Kallmeyer Collection will establish one of the largest museum collections (more than 12,000 specimens) of Ordovician invertebrate specimens in Ohio. When donated, the specimens were largely unidentified and stored en masse according to collecting locality and lithostratigraphic formation. Thus, before digitization could begin, all specimens were identified and labeled, localities were georeferenced (following iDigBio’s protocols), and the digitization workflow was developed. Digital records were then created for all specimens using the Specifiy6 biological collections databasing software.
These digital records will be combined with similar data from two other Ohio institutions and will be used to generate informational content and paleogeographic maps for online digital atlases. Atlases will serve as educational resources for the general public, K-12 students and educators, university courses focused on paleobiogeographic patterns, and species distribution modeling based research. Finally, the digital records will be incorporated into existing online biodiversity databases where they can be accessed by researchers across the globe. Continued efforts to digitize museum collections and other paleontological and biological data will increase the completeness, quality, and accessibility of the fossil record of life on Earth.
Corrine Myers, Alycia Stigall, & Bruce Lieberman presented PALEO-ENM: A VALUABLE QUANTITATIVE TOOL FOR UNDERSTANDING THE COEVOLUTION OF THE EARTH AND LIFE.
Ecological niche modeling (ENM) is a quantitative technique used to predict species’ abiotic requirements. It is a correlative method, requiring geographic information from species occurrences and the suite of environmental conditions experienced at each occurrence point. The output of these models is a set of environmental suitability rules that can be projected geographically and to different time periods to test biogeographic, ecologic, and evolutionary hypotheses. Thus, ENM is a powerful tool for understanding how a dynamic Earth environment impacts biogeographic and macroevolutionary patterns. Although developed by biologists and used extensively with modern taxa, EMN is also an effective tool for fossil analyses (PaleoENM). PaleoENM differs from ENM in the modern primarily in the process of constructing environmental layers across the study area. With analyses of modern taxa, these environmental layers can be obtained from large public databases (e.g., WorldClim). For PaleoENM, however, environmental conditions must be interpreted from the sedimentary and geochemical records and interpolated across the study area using a Geographic Information System (GIS). This presentation describes the contextual framework and important considerations for appropriate application of ENM to the fossil record and outlines best practices for reconstruction of paleoenvironmental layers. Example PaleoENM analyses of species from the Ordovician of the Cincinnati Region, the Devonian of the Appalachian basin, the Cretaceous of the Gulf Coast, and the Miocene of the Great Plains are discussed with the goal of expanding PaleoENM use to a broader range of paleontological studies.
Jon Hendricks, Alycia Stigall, Roger Portell, Erin Saupe, and Bruce Lieberman presented BIOGEOGRAPHIC RESPONSES OF MOLLUSK SPECIES TO PLIO-PLEISTOCENE ENVIRONMENTAL CHANGE IN THE WESTERN ATLANTIC.
Plio-Pleistocene mollusk species from the southeastern United States have an outstanding fossil record and have been intensively studied by paleontologists for over 150 years. Recent attention has focused on the responses of these mollusks to regional environmental changes during the Plio-Pleistocene that resulted from the closure of the Central American Seaway and the onset of northern hemisphere glaciation. Of particular interest has been the magnitude and timing of faunal extinction and turnover in relation to these events. The relationship between these environmental changes and the biogeography of the species themselves—especially across multiple time slices—however, remains less thoroughly studied within this system. Further elucidation of this relationship would help to clarify our understanding of the evolutionary dynamics of these species over geological time scales, which cannot be fully characterized by tabulation of extinction and origination rates alone.
Here we use a new dataset derived from the extensive Invertebrate Paleontology collections of the Florida Museum of Natural History to quantitatively evaluate biogeographic patterns in over 90 species of gastropod (four families) and bivalve (three families) mollusks. Our dataset contains over 12,000 georeferenced occurrence records assigned to five geographically-standardized time slices (Late Pliocene to recent). In particular, we assess range size stability of individual species over time in the face of major environmental change and compare patterns of range contraction (or lack thereof) amongst species in the time interval preceding their extinction. These analyses broadly address the question of how environmental change affects the geographic ranges of species, which is one of the most important determinants of extinction resistance in marine invertebrates.
Comments