Published: March 31, 2014

Congratulations to Rebecca Safran for receiving the Innovative Seed Grant Program award (IGP)! The size of the award is $49950. See the project summary below.

CU innovative seed grant – project summary

The overarching goal of the proposed research is to understand the interface between social behavior and parasite/pathogen transmission by testing hypotheses that integrate themes from evolutionary biology, behavioral science, and wildlife epidemiology, within the strong mathematical framework of social network theory. Social network analysis has been increasingly used in biology, especially in theoretical modeling of disease spread relative to certain network properties. The gaps in our understanding of parasite and pathogen transmission and social networks have to do with 1) the lack of experimentation, which can be difficult, impossible or unethical in some systems, 2) the difficulty obtaining accurate measures of social interactions and 3) the analytical challenges associated with robust statistical comparisons of networks. The proposed research involves describing social networks in a free-living social species (barn swallow, Hirundo rustica) using novel digital transceiver devices which will enable us to characterize fine-scale social interactions among 10 males and females at 5 independent breeding locations, for a total of 5 replicated network assemblies. In this well-studied system, a mate-selection signal, ventral plumage color, indicates parasite load: darker individuals have fewer ectoparasites compared to individuals lighter in color. Using a combination of descriptive and experimental approaches, we will test hypotheses about predictors of parasite transmission including network position and relevant features of morphology and physiology. For the first experimental manipulation, parasites will be removed by treating half the individuals in the network, and sampled several months later to measure recolonization of directly transmitted parasites relative to social network properties calculated from weighted networks based on digitally recorded contact rates between members of the tagged populations. The second experiment investigates the relationship between social network structure and parasite transmission by manipulating the network rather than the parasites. In order to alter social networks, we will manipulate host ventral plumage color, which is known to affect physiology and social behavior. There is growing recognition of the importance of individual-level heterogeneity in host behavior in the context of parasite and pathogen transmission, and this experimental approach is a powerful way to understand relative contributions of social network measures on parasite transmission as well as understanding how features of morphology and physiology influence position in social networks. This proposed research is interdisciplinary and requires expertise and innovation from biology, mathematics (network analysis) and engineering (digital transceiver tags). Social network analysis is still a young field for biologists despite the active field of network (graph) theory in statistical physics and mathematics. With this research, we will move beyond the qualitative, quasi-network approach that is often used by biologists and contribute to the development of analytical assessment of social networks and parasite/pathogen transmission, particularly in the area of comparing different networks within populations.