Some species can dwell in highly urbanized environments, like feral pigeons. Pigeons show high variability in melanin-based coloration that has been linked with physiological differences. Pr. Gasparini and collaborators have observed that the proportion of dark pigeons was higher in urbanized aereas like Paris. In a previous study, darker pigeons had higher breeding success when exposed to lead compared to pale ones. Could it be that trace metals select for darker colourations in cities? If this hypothesis is true, we should see different responses in detoxification or tolerance mechanisms depending on degree of melanism.

To answer those questions, I conducted an experiment where pigeons were exposed to lead and/or zinc, two common trace metals in Paris. We measured oxidative stress, diversity of gut microbiome and metabolomics. 

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