The Ecology and Evolution of Litter Size: An Experimental Approach

Auburn University, Auburn AL

Investigators

Abstract

Dobson 0089473 Understanding the diversity of nature and managing our natural heritage require detailed knowledge of the ways in which plant and animal populations interact with their environments. In turn, such interactions depend primarily on characteristics of life histories: patterns of reproduction, survival, and growth. This research examines the evolution of reproduction, specifically the number of offspring born into litters, in a model study species (Columbian ground squirrels of the Rocky Mountains). Experiments that cross-foster different numbers of offspring among mothers will reveal the basic principles of how mothers care for young during the important period of lactation, when young depend on milk. The experiments will reveal how mothers and young grow and survive under conditions of larger and smaller litters, and under conditions of limited and abundant food resources. The results will determine whether, as evolutionary theory predicts, there is an ideal ("optimal") number of young in litters, either among all mothers or for each individual mother. Also, the long-term success of mothers that exhibit different levels of investment in reproduction and survival will be revealed. From these tests of theory, a better explanation of the evolution of life histories should emerge. In turn, the research will provide us with improved understanding and better management of natural populations.