Meeting Abstract

P3.131  Sunday, Jan. 6  Critical amino acid allocation as a mediator of range expansion in an introduced species BRACE, A.J.*; COON, C.A.C.; MCCUE, M.D.; MCWILLIAMS, S.R.; MARTIN, L.B.; University of South Florida; University of South Florida; St. Mary’s University; University of Rhode Island; University of South Florida abrace@mail.usf.edu

The spread of introduced species into new territory can cause economic damage and disrupt native ecosystems. However, little is known about how some populations shift their ranges following an introduction. One hypothesis proposes that individuals that invest less in immune defenses than other processes, such as reproduction and growth are the most likely to successfully colonize new areas. This hypothesis rests on the assumption that investments in immunity and reproduction trade-off, though almost all support for this is indirect. To directly discern the significance of resource allocation in animal range expansions, we compared investments in immune versus reproductive and somatic tissues between house sparrows (Passer domesticus), currently undergoing range expansion in Kenya and grey-headed sparrows (Passer griseus), a native congener. We directly measured allocation of an isotope-labeled critical amino acid (13C-labeled leucine) among gonads, liver, spleen, intestines and pectoral muscle after individuals from both populations were experimentally infected with a naturally occurring intestinal (coccidian) parasite. We hypothesized that house sparrows would allocate more resources to gonads and pectoral muscle than liver and spleen compared to grey-headed sparrows. Analyses are underway but our results will provide one of the first direct studies of the role of resource allocation in range expansion.