Exploring Congruence of Fossil and Molecular Estimates of Macroevolutionary Divergence Times in Ostracoda (Crustacea)"
PI- Todd H. Oakley
The PI will conduct an empirical study of origination times of numerous evolutionary lineages of Ostracoda, a crustacean group with an excellent fossil record. A primary goal is to examine causes of observed differences between fossil and molecular divergence estimates, while considering molecular, statistical and paleontological explanations. The project includes collection of new data from five gene sequences from numerous Ostracoda, selected as the most clock-like genes of a larger panel of candidate genes. To ensure a balanced approach, the PI (whose primary training is in molecular phylogeny) will collaborate with postdoctoral researchers with primary training in morphology/taxonomy and paleontology.
This study will have broad implications for understanding methods of evolutionary divergence time estimation, and produce important new data for these studies. These studies are prerequisites for understanding the relationship between organisms and environmental factors like climate change. The results will serve as a foundation for the PI's career investigating evolutionary phenomena in Ostracoda. In addition, the PI is developing a network of opportunities for teaching and learning. First, the research results will be integrated into the PI's primary undergraduate course, which will also be improved in numerous other ways. The research also includes specific, modular projects for undergraduate research and community outreach. The PI is an active participant in multiple organizations that promote advancement of under-represented groups in science, often recruiting from these organizations to assist in research and outreach.
The primary goal of this grant was to understand the broad-scale evolution history of Ostracoda by integrating molecular and fossil data. Ostracods are excellent targets for evolutionary, ecological and global change research because of their tremendous diversity, widespread distribution, superb fossil record, and ancient origin. Furthermore, ostracods provide multiple interesting evolutionary transitions that can be used to address general evolutionary questions like those mentioned in the previous paragraph. For example, ostracod compound eyes may be phylogenetically non-homologous with other arthropod eyes. Additionally, a radical sexual dimorphism, where only males have compound eyes, has evolved multiple times and bioluminescence has evolved twice within Ostracoda, each time utilizing different chemistry. Finally, ostracod lineages have made transitions in light environment many times, alternating between bright shallow marine, dark cave, freshwater, deep sea and semi-terrestrial environments. These types characteristics can be leveraged to study important topics in macroevolution, but require a firm phylogenetic framework, the goal of this grant. We cataloged and published a summary of first fossil appearances of Ostracoda at the family level. In addition, we developed new techniques apply second generation sequencing to ostracod crustaceans, a challenge becuase of their rather small size. We developed bioinformatics tools to use transcriptomes to study phylogenetics, and we made these tools available in a publicly available package called Osiris, which runs in the Galaxy package. These developments led to the best test of ostracod monophyly, which we found strongly supported. To test this required integrating data from other arthropods, and we found support for three major clades of Pancrustacea. We named one of these Allotriocarida. We also clarified super-family level relationships of Ostracoda using transcriptome and fossil data. We used our phylogenies to examine transitions from deep to shallow seas, and gain of compound eyes. A primary educational goal was to develop the PI's undergraduate course, EEMB 102-Macroevolution. The course is very popular, now serving 180 students per year at UCSB. A major improvement was to include discussion of common anti-evolution arguments within the structure of the course. Honors students researched fossil records of ostracod families, and compiled anti-evolution arguments. Summary of products: The grant supported 3 postdoctoral scholars, 2 graduate students, and 15 undergraduate researchers. Products include 26 publications, including one newly described species (Euphilomedes chupacabra), two morphological data matrices published in MorphoBank (#175, #689) and a Dryad data repository for transcriptome data (doi:10.5061/dryad.tb40v ).
