Cost of reproduction and offspring quality in the evolution of reproductive effort

Abstract

Any organism has a limited amount of resources, which have to be partitioned among several activities such as maintenance, growth and reproduction. Reproductive effort is defined as the proportion of parental resources devoted to fecundity and offspring survival. The extent of reproductive effort is restricted by trade-offs that cancel out the advantages of increasing investment in reproduction. This thesis presents an investigation into the determinants of reproductive effort in the bank vole, Clethrionomys glareolus, focusing mainly on two major life history trade-offs i.e. cost of reproduction and trade-off between offspring number and quality. Insights into other potentially important processes such as maternal effects, density dependent selection and differential allocation of maternal effort are included. The analyses are based on data acquired by several different experimental approaches.