Meeting Abstract
70.4 Monday, Jan. 6 08:45 Using labeled nutrient tracers to reveal resource allocation in lizards with competing needs DURSO, AM*; SMITH, GD; NEUMAN-LEE, LA; FRENCH, SS; Utah State University; Utah State University; Utah State University; Utah State University amdurso@gmail.com
Animals must allocate limited resources to competing needs, necessitating trade-offs. Evidence for a fundamental trade-off between self-maintenance and reproduction is widespread but mostly indirect. We used a stable isotope label to measure how resource availability and handling stress interact to mediate decisions in energy allocation between immunity and reproduction in a reptile with a high degree of plasticity in life history traits. Fifty-six gravid female Side-blotched Lizards (Uta stansburiana) were wounded and injected with 15N-labeled leucine at the start of the experiment. They were then subjected to one week of frequent handling stress and/or food restriction in a 2×2 design. The proportion of 15N in healed wound scabs was used to evaluate energy allocation to self-maintenance, whereas 15N in eggs was used as a measure of allocation to reproduction. We also measured wound healing rate, immune function, oxidative stress, and corticosterone as indirect performance measurements of the trade-off. We found significant effects of both types of stress treatments on both direct and indirect endpoints of energy allocation. Although these lizards live only 1-2 years, individuals in stress treatments allocated more energy to self-maintenance than controls, perhaps because all lizards were in a relatively early stage of their lifetime reproductive output. Regardless, this design illustrates that both stress and energy affect allocation decisions among important life history variables.
