Project R1: Gigantism and Ovipary
|Title||Modelling sauropod life cycles and reproductive turnover: the link between gigantism and ovipary|
|Principal Investigator||PD Dr. Eva Maria Griebeler, Prof. Dr. P. Martin Sander|
In this project we focus on two hypotheses for the evolution of gigantism in sauropods that invoke not mutually independent ecological mechanisms limiting body size: (1) the body mass of the largest species and the size of land inhabited are proportional due to the decrease in per capita resources with decreasing area size which results in a higher chance of extinction (Burness et al. 2001). (2) Dinosaurs are oviparous with a large total potential reproductive output that in contrast to viviparous mammals does not decrease with increasing body size. This output enables dinosaurs to rapidly rebuild populations after environmental perturbations over evolutionary time (Janis & Carrano 1992).
We combine both empirical analyses and computer simulations. A compilation of parameters describing reproductive biology and life-history of extant phylogenetic relatives of sauropods (amniotes) enables hypotheses testing for relatives and is needed for model validation. Collection of similar data for sauropods is required for the simulation study where we consider populations of a broad range of life-cycles (defined by values assumed for parameters on reproductive biology and life-history) inhabiting different sized areas. These life-cycles cover such presumably valid for sauropods and those of the amniotes. From the simulation study we derive life-cycles that are able to persist over evolutionary time and such that may be conceivable for sauropods.
Finally, we expect to find a general relationship between the maximal body size, land area, and reproductive output for both sauropsids and sauropods.