Paleobiological Perspectives on Ecological Evolution

Core Projects

Character Displacement and Species Sorting

Which came first, the ecological divergence or the geographic co-occurrence (or neither or both)? This project uses the fossil record to trace the ecological evolution of closely related bivalve species as they move into and out of shared geographic contact. Identifying the features that enable geographic co-occurrence adds necessary insight into future clade evolution in the face of range shifts mediated by climate change.

ChioPhylo: A Molecular Phylogeny of the Venerid Bivalve Genus Chione

With funding from the NSF DDIG I’m building a species-level molecular phylogeny for a clade of marine bivalves. These Chione are at the center of my dissertation, and understanding their relatedness will greatly improve my ability to interpret morphological and biogeographic evolution in the study mentioned above. If you have come across any of the Chione linked here, please contact me and let me know. Thank you!

Morphological Integration of the Bivalve Shell

As another component to my dissertation, I am looking into whether the bivalve shell can be partitioned into areas of grouped morphological change. For instance, how does the shape of the bivalve hinge change relative to the overall shape of the shell? In the long run, I would like to couple these fine-scale morphometric analyses with detailed biomechanical studies in order to better understand ecological differentiation among closely related, and therefore morphologically similar bivalve species.

Molecular Detection of Bivalve Diet Across an Environmental Gradient

Do co-occurring bivalves compete for food? The taxonomic composition of a bivalve community is often used to infer a differential intake of food particles among its constituent species. Certain bivalves are largely labeled as filter, suspension, or deposit feeders given the anatomy of their alimentary systems and the stomach dissection of “typical” species. However, the extent to which members of a natural bivalve community partition food items from their shared habitat remains poorly understood. Terrestrial ecologists often invoke competition for food resources as an important process in structuring terrestrial communities. Marine ecologists have rarely been able to investigate the importance of this competition given the difficult nature of sampling much of the marine environment. This project aims to quantify the availability of food resources and the degree of food partitioning among bivalve species in a shared marine environment. These data will allow one of the first robust comparisons of factors driving community assembly in the marine environment to the ecological expectations derived from terrestrial systems.

Additional Projects

The Effects of Taxonomic Effort on Macroecological Patterns

With David Jablonski, and Peter Smits (UChicago)

While we can’t give an estimate of how many bivalve species escape description, we can still estimate the relative impact that continued species description has on macroecological patterns. In particular, we are looking to emphasize that this description bias carries a strong spatial and phylogenetic weight – two common variables used in macroecological studies. Our first study (Edie, Smits, and Jablonski, 2017) develops an approach to estimating the trends in description rate and their implications for taxonomic saturation. For the next iteration of the model, we plan to incorporate biological characteristics of species to inform our estimates of taxonomic saturation.

The Nature of Bivalve Invasions

With Nicole Bitler, and David Jablonski (Uchicago)

International shipping and, at first, lax ballast regulation, led to the many different bivalve invasions. This unintentional natural experiment gives us the chance to characterize the ecological nature of these invasions and to extract predictions for the plasticity of bivalve ranges.

Sampling Chione elevata (Say 1822) from the Grotto Beach Formation (Pleistocene of San Salvador, Bahamas).

Sampling Chione elevata (Say 1822) from the Grotto Beach Formation (Pleistocene of San Salvador, Bahamas).

Crude 3D photogrammetry of Spondylus specimen.

Crude 3D photogrammetry of Spondylus specimen.

Sunrise or Sunset? Sunrise from North Point, San Salvador, Bahamas.

Sunrise or Sunset? Sunrise from North Point, San Salvador, Bahamas.

Copyright © 2017 Stewart Edie