The goal of ecology is to understand feedbacks between living organisms and their environment. Understanding this is more acute amid the present rate of biospheric change associated with human impacts on the environment, and the resulting effects on organisms. Today, ecologists can study a few organisms in a given landscape or ecosystem at a time, which can require a laborious effort. Furthermore, when studying taxa in isolation, critical relationships that exist within the ecosystem (such as food web relationships) may be missed, and biodiversity cannot be considered as an important factor. To address this fundamental problem, we developed a new interdisciplinary method to characterize vertebrate communities based on blow fly (Diptera: Calliphoridae) data. We use a combination of chemical analyses and population genetics of active blow flies, to estimate the diversity and abundance of vertebrate animals in any given landscape over any time period. The method is based on the sequence analysis of fly gut contents, the chemical analysis for fecal metabolites, and stable isotope analysis of the fly itself to determine its larval origin. Combined with abiotic data (wind speed, temperature), and fly population structure, we can estimate the diversity and abundance of vertebrate animals in a given landscape.
Results/Conclusions
We present empirical data that supports each component of our model. Stable isotope analysis of flies developed as larvae on different substrates demonstrates that the C isotopes indicate food source, and that the N isotopes indicate trophic level. In the determination of adult food source, DNA sequencing of fly guts produced positive results in ~30% of wild caught flies, with species ranging from common urban species such as human and dogs, to much more rare tiger, albeit the sampling site was < 2 miles from the city zoo. In determining if the last meal was fecal in origin (indicative of a potentially living animal), fecal metabolites assays were 100% accurate in laboratory based assays, and approximately 10% of wild caught flies had the presence of feces. Combining this data with the population structure and kinship of the blow flies collected from various sites across central Indiana, we can estimate the approximate diversity and abundance of vertebrate species. This new approach to obtaining difficult to collect data on multiple species at one time will transform the way vertebrate ecological research is undertaken, and lead to a greater understanding of the ecosystem processes affected by such anthropogenic factors.