Karl Mauritsson
School of Engineering Science
Karl Mauritsson defends his PhD thesis "Application of Metabolic Theory in Models for Growth of Individuals and Populations".
The PhD thesis defence will be held in Room G110 at the University of Skövde.
Abstract
Animals acquire energy from the food they eat and use it to grow, reproduce, and maintain homeostasis (a stable internal physical and chemical environment). Based on models of individual metabolism (energy usage), metabolic theories in ecology analyse various ecological processes, such as population growth and interactions between organisms in food webs. This work develops and applies metabolic theory in three different areas of ecology: 1) individual growth under resource limitation, 2) age and size at sexual maturity, and 3) the accumulation of environmental toxins and their impact on populations of marine mammals. In all these, mathematical modelling plays a significant role.
To strengthen the foundation of metabolic theory, a new model for individual body growth under limited food availability is presented. The model considers several aspects overlooked by many previous models of individual growth, including the organism's regulation of the energy allocated to maintenance of various body structures at the expense of growth. The model has been calibrated and validated against data obtained from experiments conducted on insects.
One application area of metabolic theory is life-history theory, the study of how organisms allocate their resources to survive, grow, and reproduce in a way that maximizes their contribution to future gene pools. Two of the most critical traits for an organism's lifetime reproduction are size and age at sexual maturity, which can often be adjusted as a response to environmental conditions. Here, it is examined how these traits can be predicted under different resource conditions using life-history theory in combination with various models of survival and body growth, including the newly developed model.
Bioaccumulation of toxins in organisms is a serious environmental problem, particularly affecting marine mammals because they occupy high positions in the food chain and have large fat reserves where many substances can bind and persist for extended periods. A new mathematical model is presented that can be used to analyse the bioaccumulation of environmental toxins and their consequences for populations of marine mammals. The model describes how toxins enter bodies via food and are accumulated or transferred to the offspring, how accumulated toxins over time cause tissue damage, how this affects individual survival and reproduction, and the temporal consequences for the population's size and age structure. The model has been calibrated and validated for Baltic grey seals exposed to PCBs. Metabolic theory was applied in the determination of model parameters.
Supervisors
Tomas Jonsson, Professor in Bioscience, University of Skövde
Opponent
Douglas Glazier, Professor in Biology, Juniata College, Pennsylvania, USA
Committee
Peter Eklöv, Professor, Uppsala University
Magnus Huss, Senior Lecturer, Swedish University of Agricultural Sciences
Ullrika Sahlin, Senior Lecturer, Lund University