It is well known that an individual's environment, genetic code, and gene by environment interactions have an effect on its overall phenotype. However, there is a growing body of work that shows that parents can have an effect on their offspring's phenotype beyond the inherited genetic code. Studies have shown that parents may affect their offspring through physiological mechanisms such as egg provisioning and epigenetic effects and through behavioral mechanisms such as maternal care. In many of these cases, the parental effect is triggered by an environmental cue. Previous work has shown that density can impact immune function and cuticle color in insects - two phenotypic traits that are pleiotropically linked. Additional work has shown that parental density can have impacts on offspring immune function, as well. However, previous studies utilized insect species that show a strict density dimorphic phenotype where individuals reared at high densities exhibit increased immune function and much darker cuticles than their low density counterparts, which is not an accurate representation of most insect systems as most insect systems show a more continuous response to density effects. Also, previous work has not determined the parental origin of density effects on offspring immune function and cuticle color. It has been suggested that parental density effects may be due to maternal egg provisioning and that paternal effects may be minimal. However, knowledge of parental origin would give us a better insight into the possible mechanisms of these density driven parental effects and provide a direction for future research. In my study, we used Drosophila melanogaster in order to determine (1) if density affects immune function and cuticle color in a species that shows a continuous response to density, (2) if parental density affects offspring immune function and cuticle color, and (3) if the source of these parental effects are of a maternal origin only or if these effects are of a paternal origin, as well. We found that there is an effect of density on immune function and cuticle color in the parents in a more common insect system and parental density had an effect on offspring phenotype, as well. Most notably, we found that, in addition to the effects of maternal density, these parental effects on offspring phenotype were a response to paternal density, as well.
Master of Science (M.S.)
College of Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Davis, Dana, "The Effect of Parental Population Density on Offspring Immune Function" (2017). Electronic Theses and Dissertations, 2004-2019. 5354.