Biologists predict that stress early in life should have a larger effect on organisms than the same stress experienced later in life. This theory is called the developmental stress hypothesis and if correct means that early stress experiences may have long last effects that impact an individual fitness by altering cues that are used by animals to assess each other as mates and/or competitors. If this hypothesis is correct then may taking into account environmental stressors it is possible to design more effective preservation and conservation actions as we know the mechanisms for how and why certain individuals will mate with each other and produce offspring that survive. This project will test the developmental stress hypothesis by examining physiological, immunological, developmental, and behavioral consequences of exposure to low levels of mercury in a well-studied bird?the zebra finch. Mercury is a global toxin but we know little about how small non-lethal amounts of mercury harm the body. Mercury contamination has been described by the current Federal administration as the "most important global chemical issue facing us today", so increasing our understanding of the impact on wildlife of this pernicious and mobile toxin will have important implications for national and international efforts to regulate mercury pollution. Graduate and undergraduate students participating in this project will indicate whether early life exposure to mercury is more damaging than later exposure to the same small amount of mercury. Pilot data indicate that the immune system will be suppressed, brain functions impaired, and breeding severely depressed; and that these effects will be most notable in the case of early-life exposure to mercury. This could change our perception of what a "safe" level of mercury is. As the zebra finch brain is a model for understanding human speech learning this project will also give insight as to how mercury affects human health.
