UNDERSTANDING THE RELATIONSHIP BETWEEN DARRIWILIAN GRAPTOLITES’ FUNDAMENTAL NICHE AND EXTINCTION RISK

The role of an organism’s fundamental niche in predicting extinction risk is poorly understood, however graptolites, early Paleozoic zooplankton, have been extensively sampled and can provide a comprehensive data set by which to study this role. To model the fundamental niche of various graptolite species, those from the Darriwilian Stage of the Ordovician System in Baltica have been chosen for study because these species are diverse and particularly well sampled. Biofacies data were collected from the Darriwilian interval of the Lerhamn and Krapperup cores at Lund University and includes lithology, organisms present, trace fossils and any other notable features. Geochemical analysis of samples from each core will provide further insight into the biotope of individual species by comparing the geochemical conditions of each core, interpreted to have been deposited within a deep shelf setting, against the proposed conditions of the Darriwilian mesopelagic and epipelagic biotopes. With the aid of fundamental niche modeling tools such as MaxEnt, these data on species distributions relative to observed biofacies conditions will help to illuminate the conditions that individual species optimally inhabited. Furthermore, the relationship between niche and mean species duration can be explored to determine the disparity of graptolites’ mean species durations between those that inhabit mesopelagic versus epipelagic zones and which features of a species’ niche most influence extinction risk.