Submission Date

4-12-2021

Document Type

Paper- Restricted to Campus Access

Department

Biology

Adviser

Kathryn Goddard

Committee Member

Denise Finney

Committee Member

Samantha Wilner

Department Chair

Rebecca Lyzack

External Reviewer

Jeannette Dumas

Distinguished Honors

This paper has met the requirements for Distinguished Honors.

Project Description

Decades worth of pollutants continue to build up and leach into the waterways of the eastern United States such as poly aromatic hydrocarbons (PAHs) and other dioxin-like compounds (DLCs). These pollutants have immediate and lingering effects on the fishes inhabiting these waterways. Fundulus heteroclitus has long been a premier model organism researching forced evolution to resist PAHs and DLCs toxicity as it populates waters downstream of many EPA designated superfund sites. The resistance mechanism has been thought to derive from the Aryl Hydrocarbon Receptor (AHR) pathway encoding a ligand activated transcription factor that drives expression of xenobiotic enzymes such as Cytochrome P450. In an attempt to elucidate this resistance mechanism, we captured and characterized subspecies and single nucleotide polymorphisms (SNPs) in Exon 10 of AHR1a in Fundulus heteroclitus downstream of two EPA designated superfund sites in the Lower Darby Creek in John Heinz National Wild Life Refuge in Philadelphia, Pennsylvania. In this study we report the subspecies fixation of Fundulus heteroclitus macrolepidotus (northern) subspecies in the Lower Darby Creek and Muckinipattis Creek, tributaries of Delaware bay. As well as the subspecies fixation of Fundulus heteroclitus heteroclitus (southern) in Ocean City, New jersey. Additionally, although SNPs discovered in exon 10 of AHR1a were significantly divergent from control populations, we cannot conclude that exon 10 of AHR1a is the mode of resistance in Fundulus heteroclitus in the Lower Darby Creek.

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