Biology (B.S.B.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. Tavis Anderson


To be successful, an animal must eat, grow, and reproduce. With limited resources, there are tradeoffs between these critical life history parameters but the direction of the tradeoffs is largely unknown in a changing environment. To determine whether environmental context affects life-history tradeoffs, I surveyed and quantified investment into reproduction, growth, and a proxy for immunity (parasitism), in the mummichog, Fundulus heteroclitus, a common inhabitant of salt marshes in Georgia. Three salt marsh sites along coastal Georgia (Shellman Bluff, Skidaway Island, and Tybee Island) were selected using a proxy for anthropogenic disturbance (impervious surface), which also fell along a gradient in chronic stress. I measured reproductive investment, parasitism as a proxy for immunity, and fish condition. I found that parasitic infection, my proxy for immune investment, affected a fish’s investment into reproduction but that there were only differences in fish that were chronically stressed. Specifically, in stressed environments fish appeared to invest in reproduction to the detriment of immunity and body condition. However, in environments with fish that were less stressed, investment into growth, immunity, and reproduction was maintained almost equally. These data reveal how environmental context can affect important life-history tradeoffs, and suggest that though individuals may be able to reproduce in stressful conditions, they may suffer more from infectious disease.