Evolution 2016: Using Field Experiments to Understand Life-History Trade-Offs

Anolis sagrei. Photo by Alex Gunderson

The concept of trade-offs, that if you want to increase your performance in one function you have to decrease performance in another, is fundamental to ecology and evolution. However, detecting trade-offs and the underlying mechanisms that give rise to them is extremely difficult. In his talk, Bob Cox summarized years of research that he and his collaborators have done to understand life-history trade-offs in realistic ecological contexts using the brown anole (Anolis sagrei). Bob’s general approach is to experimentally manipulate the reproductive effort of individuals by removing ovaries and testes before releasing them onto cays in the Bahamas. He then estimates important ecological and physiological parameters such as survival, fat reserves, and immune function to see if he can detect trade-offs between reproductive effort and these other traits. In general, he has found that reproductive investment significantly decreases survival and physiological performance and that effects are often contingent upon factors such as the presence or absence of predators. Check out Bob’s website for a more information about his integration of experimental, ecological, and evolutionary studies to understand how trade-offs shape animal life-histories.