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Urbanization and distance shape population structure in Fundulus heteroclitus
Jeffrey A Markert1, Matthew T Rock1,2, Bryan W Clark3
1Department of Biological Sciences, Providence College, 1 Cunningham Square, Providence, RI 02918, United States.
Journal of Urban Ecology
|July 1, 2025
Summary
Mummichog fish populations near New Bedford Harbor have evolved genetic adaptations to tolerate polychlorinated biphenyls. Pollution drives genetic differentiation, particularly at genes regulating the aryl hydrocarbon receptor system.
Area of Science:
- Environmental toxicology
- Population genetics
- Ecotoxicology
Background:
- New Bedford Harbor is a Superfund site with significant polychlorinated biphenyl contamination from mid-20th century industrial dumping.
- Mummichogs (Fundulus heteroclitus) are common fish susceptible to polychlorinated biphenyls, but some populations exhibit tolerance.
- The aryl hydrocarbon receptor system is implicated in adaptive tolerance to pollutants.
Purpose of the Study:
- To investigate the population genetic structure of mummichogs in relation to pollution levels at New Bedford Harbor.
- To identify genetic loci associated with adaptive tolerance to polychlorinated biphenyls in Fundulus heteroclitus.
Main Methods:
- Conducted population genetic analysis of 444 mummichogs from Massachusetts and Rhode Island estuaries.
- Utilized 55 single nucleotide polymorphism (SNP) loci to assess genetic variation.
- Compared allele frequencies between polluted and cleaner estuarine sites.
Main Results:
- Mummichog populations near New Bedford Harbor show large population sizes and restricted gene flow.
- Strong genetic differentiation was observed at a small geographic scale between polluted and clean sites.
- Allele frequency differences at loci within the aryl hydrocarbon receptor system significantly drive this genetic differentiation.
- Pollution-tolerant alleles are present at low frequencies in cleaner habitats.
Conclusions:
- Fundulus heteroclitus populations exhibit localized adaptive genetic responses to polychlorinated biphenyl pollution.
- The aryl hydrocarbon receptor system plays a key role in the evolution of pollution tolerance in mummichogs.
- Genetic differentiation highlights the impact of environmental contaminants on local fish populations.
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