Food supplementation and testosterone interact to influence reproductive behavior and immune function in Sceloporus graciosus

Mayté Ruiz, Susannah S. French, Gregory E. Demas, Emília P. Martins

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


The energetic resources in an organism's environment are essential for executing a wide range of life-history functions, including immunity and reproduction. Most energetic budgets, however, are limited, which can lead to trade-offs among competing functions. Increasing reproductive effort tends to decrease immunity in many cases, and increasing total energy via supplemental feedings can eliminate this effect. Testosterone (T), an important regulator of reproduction, and food availability are thus both potential factors regulating life-history processes, yet they are often tested in isolation of each other. In this study, we considered the effect of both food availability and elevated T on immune function and reproductive behavior in sagebrush lizards, Sceloporus graciosus, to assess how T and energy availability affect these trade-offs. We experimentally manipulated diet (via supplemental feedings) and T (via dermal patches) in males from a natural population. We determined innate immune response by calculating the bacterial killing capability of collected plasma exposed to Escherichia coli ex vivo. We measured reproductive behavior by counting the number of courtship displays produced in a 20-min sampling period. We observed an interactive effect of food availability and T-patch on immune function, with food supplementation increasing immunity in T-patch lizards. Additionally, T increased courtship displays in control food lizards. Lizards with supplemental food had higher circulating T than controls. Collectively, this study shows that the energetic state of the animal plays a critical role in modulating the interactions among T, behavior and immunity in sagebrush lizards and likely other species.

Original languageEnglish (US)
Pages (from-to)134-139
Number of pages6
JournalHormones and Behavior
Issue number2
StatePublished - Feb 2010
Externally publishedYes


  • Context-dependent
  • Energy allocation
  • Innate immunity
  • Life history
  • Resources
  • Sceloporus
  • Trade-offs

ASJC Scopus subject areas

  • Endocrinology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience


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