Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name

Organismal Biology and Ecology

Department or School/College

Division of Biological Sciences

Committee Chair

H. Arthur Woods

Commitee Members

Chalres Palmer, Douglas Emlen


Extended Phenotype, Holometaboly, Metamorphosis, Physiological Ecology, Pupation Chambers


University of Montana


Extended phenotypes can serve interesting physiological functions and their externality provides ready opportunity to manipulate and examine their functions and costs. One such set of extended phenotypes are below-ground pupation chambers made by a wide range of insects and whose function is unknown and costs unquantified. We use a series of lab and field experiments to examine the cost and benefit of chambers made by the hawkmoth, Manduca sexta (Sphingidae), whose larvae lose up to 60% of their body mass during chamber construction. Our study shows that these chambers provide critically important free space in which individuals transition from larvae to pupae and from pupae to adults, and that the cost of making chambers, as measured by pre-pupal mass loss, increases rapidly in dry soils. However, we found no evidence that chambers provide any benefit during metamorphosis, nor do they affect the microclimate or prevent predation by soil pathogens or predators. These results are broadly applicable to holometabolous insects and provide perhaps the most basal explanation for the evolution of complex chamber building behavior.



© Copyright 2013 Jonathan Cooley Sprague