The "Great Ordovician Biodiversification Event"
The Ordovician time interval witnessed a dramatic increase in the diversity of marine invertebrates such as brachiopods, arthropods and mollusks. This important period is referred to as the “Great Ordovician Biodiversification Event” or GOBE. In contrast to the Cambrian Explosion during which major metazoan bauplans emerged in the geological record, the GOBE is rather characterized by an aggregation of biodiversity on intermediate to low systematic levels (i.e. families to species). It is quite clear that the dispersed palaeogeographical setting during the Ordovician presented excellent framework conditions for the diversification of taxa by providing ample opportunities for speciation that is driven by geographically induced spatial divergence (allopatric). However, the significance of intrinsic controls on the GOBE is poorly constrained. Intrinsic factors represent effects which emerge from interactions between biota within ecosystems such as predation or competition. Especially the role of competition in shaping diversity during the GOBE remains unclear. This project attempts to test if and to what extent competition drives ecological partitioning of species (=diversification) on the habitat scale.
The idea is chiefly based on some results of my PhD thesis. We have postulated that the extremely low diversity left by the end-Permian mass extinction enabled species to occupy a wide range of habitats simply because lacking competitors. The “tipping point” after which an ecosystem might switch back to rather competition-controlled conditions should be expressed in a significant rise in beta diversity (habitat partitioning). Species migrate to places, or split along environmental gradients, where they are not outcompeted by newly arrived or evolved rivals and thereby increase the overall biodiversity of the area (gamma diversity) without necessarily increasing the diversity on site (alpha diversity). The first logical step was to look whether or not pre-extinction ecosystems show a higher habitat differentiation with so far mixed results. The second logical step would be to test if habitat differentiation is increasing during further progressing recovery in the Middle Triassic. This is exactly what my PhD advisor is currently doing with a new PhD-Student at the University of Zürich.
Yet the third logical step is to test whether or not habitat partitioning increases throughout other diversification events. One quick look at global diversity compilations reveal that the Early and Middle Ordovician represents a most promising time interval.
Involved people (so far)
- Me (PI)
- Kevin Bylund Link: Kevin is a patient paleontologist with a keen interest in ammonoids. He knows virtually every rock in Utah and greets tarantulas by handshake. He has helped me tremendously since 2009 when I first came out to the western US. A sedulous explorer that knows where the good stuff is!
- My hosts at the Museum für Naturkunde Berlin are Martin Aberhan and Dieter Korn.
- Melanie Tietje: Biologist, office mate that I consulted way too often because of my rather troglodyte-like R skills.
Funding for the first year of data exploration was provided by the SNF (Swiss National Science Foundation) from 03/16 - 02/17. The full field campaign is now supported by the DFG (German Research Foundation).