Evolutionary Toxicogenomics of the Striped Killifish (Fundulus majalis) in the New Bedford Harbor (Massachusetts, USA).

Paolo Ruggeri,Douglas Crawford,Xiao Du,Marjorie Oleksiak

doi:10.3390/ijms20051129

Abstract

In this paper, we used a Genotyping-by-Sequencing (GBS) approach to find and genotype more than 4000 genome-wide SNPs (Single Nucleotide Polymorphisms) from striped killifish exposed to a variety of polychlorinated biphenyls (PCBs) and other aromatic pollutants in New Bedford Harbor (NBH, Massachusetts, USA). The aims of this study were to identify the genetic consequences of exposure to aquatic pollutants and detect genes that may be under selection. Low genetic diversity (HE and π) was found in the site exposed to the highest pollution level, but the pattern of genetic diversity did not match the pollution levels. Extensive connectivity was detected among sampling sites, which suggests that balanced gene flow may explain the lack of genetic variation in response to pollution levels. Tests for selection identified 539 candidate outliers, but many of the candidate outliers were not shared among tests. Differences among test results likely reflect different test assumptions and the complex pollutant mixture. Potentially, selectively important loci are associated with 151 SNPs, and enrichment analysis suggests a likely involvement of these genes with pollutants that occur in NBH. This result suggests that selective processes at genes targeted by pollutants may be occurring, even at a small geographical scale, and may allow the local striped killifish to resist the high pollution levels.

Highlights

Anthropogenic stressors are a major threat to ecological balance in both terrestrial and aquatic environments
Illumina GBS sequencing using the TASSEL pipeline with the Fundulus heteroclitus reference genome recovered 5403 single nucleotide polymorphisms (SNPs) found in at least 80% of individuals with 136 individuals having at least 70% of all SNPs
These individuals were collected in four sampling sites representative of a polychlorinated biphenyl (PCB) gradient measured as standard dry mass weight of the sediment, as reported in Roark et al [36]

Summary

Introduction

Anthropogenic stressors are a major threat to ecological balance in both terrestrial and aquatic environments. Most anthropogenic stressors are related to several classes of chemical compounds that are directly or indirectly released in the environment by human activities [1] Most of these chemicals are released in terrestrial environments, they affect marine environments because of the tight relationship between terrestrial and marine ecosystems [2]. More than 80% of terrestrial contaminants reach coastal and oceanic waters [3] These pollutants can negatively impact ecosystem functioning of both marine coastal and pelagic areas by reducing the primary production and increasing respiration [4], and these negative effects contribute to demographic instability of several marine species, which induces strong ecological shifts in species composition as well as physiological and evolutionary changes in wild populations [5,6]. Pollutants might act as a selective force, which eliminates individuals that cannot tolerate the pollutants and reduces genetic variability [7,8]

Objectives

Methods

Results

Discussion

Conclusion