Meeting Abstract

P3.84  Wednesday, Jan. 6  Capitalizing on Income: Using Stable Isotopes to Understand Reproductive Allocation in the Flesh Fly, Sarcophaga crassipalpis JORDAN, D. C. *; WESSELS, F. J.; HAHN, D. A.; University of Florida; University of Florida; University of Florida dianis@ufl.edu

Resources used for reproduction can come from a variety of sources, however, these sources are often categorized into two general resource pools, capital and income. Capital resources are acquired and stored prior to the reproductive period, while income resources are resources that are acquired and immediately funneled into reproduction. These terms have led to the classification of organisms as capital or income “breeders”, although these categories overlook organisms that use a combination of capital and income during reproductive allocation. Most likely, the majority of organisms fall along a continuum between capital and income breeding. However, a fundamental problem with identifying where organisms fall along the continuum is separating resource acquisition from resource allocation. We used stable isotopes to separate capital and income resource pools in the flesh fly, S. crassipalpis, by switching isotopically distinct diets at the onset of the reproductive period (immediately following adult metamorphosis). We track the allocation of capital and income to somatic and reproductive tissue across two subsequent clutches of eggs. In addition, we characterized the turnover of polar and neutral lipids in somatic and reproductive tissue over two clutches. Our results show that S. crassipalpis uses primarily income resources to provision eggs, however, a small amount of capital resources are used to provision the first clutch (~18% capital) but the second clutch is provisioned almost entirely with income resources (~4% capital). These findings may reflect the life-history of flesh flies, which are highly mobile and feed on a spatially and temporally patch resource.