Testing how nutrients affect offspring traits using cannibalism as a model

In many species of spiders, females kill and consume males either before, during or after mating. Cannibalism has been shown to benefit females by increasing the quality of the offspring that they produce. Although, the mechanism responsible for this benefit of consuming the male body remains unclear. The benefit to females of consuming males is especially interesting in species where males are very small. In these cases, it seems there is a chemical in the male body that can benefit females even when it is consumed in low concentrations. The goal of this project is to study cannibalism in spiders to determine which chemicals in the male body result in benefits to female offspring production, especially chemicals like micronutrients and dietary essential nutrients that can have benefits at low concentrations. It is hoped that the information that is learned about micronutrients and dietary essential nutrients in spiders will have implications for better understanding the nutritional ecology of a wider range of species. In addition to generating new knowledge, this project will have broader benefits to society by training students to be scientists, and through public outreach on the role of spiders in ecosystems. Cannibalism occurs in a diversity of spiders and has been shown to have benefits to offspring production, including species with a high degree of size dimorphism (i.e., very small males). Despite significant research on the occurrence of male cannibalism, the chemicals in the male body that are responsible for the benefit of cannibalism remain unclear. It is likely that micronutrients or dietary essential nutrients are responsible for the nutritional benefit of male cannibalism, given that males are a small part of the female diet, especially in species with small males. The goal of this study is to determine which micronutrients, dietary essential amino acids, or dietary essential fatty acids are responsible for the nutritional benefit of male cannibalism in spiders. At a phylogenetic scale, the work will compare the body composition of males and females of many spider species to test if males concentrate certain nutrients in their bodies. At the ecological scale, the work will compare male spiders of two focal species with insect prey to determine if males represent a nutritionally-unique prey item. Finally, at an experimental scale, a study will test if nutritional supplements containing putative nutrients identified in male bodies have the same nutritional benefits as consuming the male body itself. This research provides a model system for increasing our understanding of micronutritional ecology, which is an emerging area of nutritional ecology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.