Genetic structure and mtDNA diversity of Fundulus heteroclitus populations from polycyclic aromatic hydrocarbon-contaminated sites.

Genetic structure and diversity of mummichog (Fundulus heteroclitus) populations were investigated using mitochondrial DNA (mtDNA) sequences. Forty-six haplotypes were identified among 208 mummichog from the Elizabeth and York Rivers in Virginia, USA. No evidence of decreased gene or nucleotide diversity for mummichog from polycyclic aromatic hydrocarbon (PAH)-contaminated sites was observed. However, based on mtDNA data from 17 sites, a significant correlation (Mantel analysis, p = 0.035) was noted between genetic distance (F(ST)) and PAH concentration but not between genetic distance and geographic distance. Mummichog from the most heavily PAH-contaminated site, Atlantic Wood (AW), were genetically distinct from those of other Elizabeth River sites. At AW, high frequencies of several divergent haplotypes were observed that were more closely allied to the northern mummichog than to the more abundant southern form in the Chesapeake Bay. These data suggested that a locally stable population existed at the AW site. This conclusion is consistent with the observation that mummichog from the AW site display enhanced tolerance to PAH contamination relative to mummichog from noncontaminated sites. Conclusions about gene diversity and the correlation between genetic distance with site differences in PAH concentrations were also consistent with those from tandem genetic analyses based on allozymes.