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Stable Genetic Structure and Connectivity in Pollution-Adapted and Nearby Pollution-Sensitive Populations of Fundulus Heteroclitus
Citation:
Nunez, J., L. Biancani, P. Flight, D. Nacci, D. Rand, D. Crawford, AND M. Oleksiak. Stable Genetic Structure and Connectivity in Pollution-Adapted and Nearby Pollution-Sensitive Populations of Fundulus Heteroclitus. Royal Society Open Science. Royal Society Publishing, London, Uk, 5(5):171532, (2018). https://doi.org/10.1098/rsos.171532
Impact/Purpose:
This manuscript describes experimental studies that contribute to our understanding of the ecological risks associated with human-mediated stressors. Here, we assessed genome wide genetic patterns using field-collected samples to characterize genetic variation among fish from wild populations, hypothesizing that population genotypes might vary due to migration barriers related to local toxic pollutants. Results of these studies demonstrate the value of comparative genetics to diagnose and predict effects of ecological stressors and characterize the mechanisms and costs of compensatory responses to such stressors by wild populations. General impacts from this contribution include improved understanding by managers and scientists of links between human activities, natural dynamics, ecological stressors and ecosystem condition.
Description:
Populations of the non-migratory estuarine fish Fundulus heteroclitus inhabiting the heavily polluted New Bedford harbor estuary have shown inherited tolerance to local pollutants introduced to their habitats in the past 100 years. We investigated signals of this recent adaptation in the genetic structure of F. heteroclitus populations across small geographic scales in the estuary. Whole mitochondrial genomes were analyzed for 133 F. heteroclitus from seven nearby collection sites. Pollution-adapted fish were collected at four sites along the New Bedford harbor pollution cline (~5 km distance); pollution-sensitive fish were collected just adjacent to the pollution cline as well as about 20 km away in two relatively unpolluted locations. Additionally, we used microsatellite analyses to test genetic signal stability over three F. heteroclitus generations in both pollution-adapted and sensitive individuals collected from two sites at two different time points (1999/2000 and 2007/2008). MtDNA genome analyses revealed that both pollution-adapted and –sensitive populations harbor similar haplotype (Hdadapted = 0.977, Hdsensitive = 0.985) and nucleotide diversity (πadapted = 0.064%, πsensitive = 0.056%) and little population structure. Microsatellite analyses revealed no genetic differentiation between pollution sensitive and adapted populations, and this structure appears to be stable over the last decade. As with mtDNA, microsatellites also showed no genetic diversity differences between pollution sensitive and adapted populations. Overall, both analyses reveal high historical migration between pollution-sensitive and –adapted populations. No natural selection signatures were observed between populations, and no single nucleotide polymorphisms were fixed within fish from any site. However, mitochondrially encoded complex I and V subunits have 16 segregating SNPs that result in non-synonymous amino acid substitutions, and mitochondrial tRNAs have 15 segregating SNPs.
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DOI: Stable Genetic Structure and Connectivity in Pollution-Adapted and Nearby Pollution-Sensitive Populations of Fundulus Heteroclitus