John W. Bickham Jeffery K. Wickliffe Thomas W. Custer Christopher R. Dahl 2001 DNA sequence analysis of a 215 base-pair region of the mitochondrial cytochrome <i>b</i> gene was used to examine genetic variation and search for evidence of an increased mutation rate in black-crowned night-herons. We examined five populations exposed to environmental contamination (primarily PAHs and PCBs) and one reference population from the eastern U.S. There was no evidence of a high mutation rate even within populations previously shown to exhibit increased variation in DNA content among somatic cells as a result of petroleum exposure. Three haplotypes were observed among 99 individuals. The low level of variability could be evidence for a genetic bottleneck, or that cytochrome <i>b</i> is too conservative for use in population genetic studies of this species. With the exception of one population from Louisiana, pair-wise Phi_st estimates were very low, indicative of little population structure and potentially high rates of effective migration among populations. application/pdf 10.1023/A:1016711401809 en Springer Cytochrome b sequences in black-crowned night-herons (Nycticorax nycticorax) from heronries exposed to genotoxic contaminants article