Development and population divergence

Changes in gene expression, coupled by biochemical, physiological, and behavioral alterations play a critical role in adaptation to environmental stress. To explore the ways natural populations may have adapted to local polluted environments, we took advantage of natural populations of the teleost fish Fundulus heteroclitus, one of the few studied fish species in North America that has established resistant populations in highly contaminated urban estuaries. We quantified expression of about one-fourth of Fundulus genes in all 40 stages of Fundulus embryogenesis. Waves of differential gene expression are associated with the different hallmarks of development (e.g., gastrula, vascular and organ development). Contrasting developmental patterns of gene expression and phenotypic variation among populations indicate that individuals from heavily polluted sites have an altered developmental program during critical developmental stages. Exposure to polluted sediment during development has a greater effect on individuals from "clean" sites, suggesting that individuals from polluted sites have evolved mechanisms to enhance developmental canalization.