Dataset Information

Evaluating the Potential Fitness Effects of Chinook Salmon (Oncorhynchus tshawytscha) Aquaculture Using Non-Invasive Population Genomic Analyses of MHC Nucleotide Substitution Spectra.

ABSTRACT: Genetic diversity plays a vital role in the adaptability of salmon to changing environmental conditions that can introduce new selective pressures on populations. Variability among local subpopulations may increase the chance that certain advantageous genes are passed down to future generations to mitigate susceptibility to novel diseases, warming oceans, loss of genetic stocks, and ocean acidification. Class I and II genes of the major histocompatibility complex (MHC) are crucial for the fitness of Chinook salmon due to the role they play in disease and pathogen resistance. The objective of this study was to assess the DNA sequence variability among wild and hatchery populations of Alaskan Chinook salmon at the class I α1 and class II β1 exons of the MHC. We hypothesized that the 96 wild samples taken from the Deshka River would display greater levels of observed heterozygosity (Ho) relative to expected heterozygosity (He) in suggesting that individuals with similar phenotypes mate with one another more frequently than would be expected under random mating patterns. Conversely, since no mate selection occurs in the William Jack Hernandez Sport Fish hatchery, we would not expect to see this discrepancy (He = Ho) in the 96 hatchery fish tested in this study. Alternatively, we hypothesized that post-mating selection is driving higher levels of observed heterozygosity as opposed to mate selection. If this is the case, we will observe higher than expected levels of heterozygosity among hatchery salmon. Both populations displayed higher levels of observed heterozygosity than expected heterozygosity at the Class I and II loci but genetic differentiation between the spatially distinct communities was minimal. Class I sequences showed evidence of balancing selection, despite high rates of non-synonymous substitutions observed, specifically at the peptide binding regions of both MHC genes.

SUBMITTER: Wilson EJ

PROVIDER: S-EPMC9951711 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature

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Evaluating the Potential Fitness Effects of Chinook Salmon (<i>Oncorhynchus tshawytscha</i>) Aquaculture Using Non-Invasive Population Genomic Analyses of MHC Nucleotide Substitution Spectra.

Wilson Evan J EJ Shedlock Andrew M AM

Animals : an open access journal from MDPI 20230208 4

Genetic diversity plays a vital role in the adaptability of salmon to changing environmental conditions that can introduce new selective pressures on populations. Variability among local subpopulations may increase the chance that certain advantageous genes are passed down to future generations to mitigate susceptibility to novel diseases, warming oceans, loss of genetic stocks, and ocean acidification. Class I and II genes of the major histocompatibility complex (MHC) are crucial for the fitnes ...[more]

PMID: 36830380

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Project description:The Columbia River and its tributaries provide essential spawning and rearing habitat for many salmonid species, including Chinook salmon (Oncorhynchus tshawytscha). Chinook salmon were historically abundant throughout the basin and Native Americans in the region relied heavily on these fish for thousands of years. Following the arrival of Europeans in the 1800s, salmon in the basin experienced broad declines linked to overfishing, water diversion projects, habitat destruction, connectivity reduction, introgression with hatchery-origin fish, and hydropower development. Despite historical abundance, many native salmonids are now at risk of extinction. Research and management related to Chinook salmon is usually explored under what are termed "the four H's": habitat, harvest, hatcheries, and hydropower; here we explore a fifth H, history. Patterns of prehistoric and contemporary mitochondrial DNA variation from Chinook salmon were analyzed to characterize and compare population genetic diversity prior to recent alterations and, thus, elucidate a deeper history for this species. A total of 346 ancient and 366 contemporary samples were processed during this study. Species was determined for 130 of the ancient samples and control region haplotypes of 84 of these were sequenced. Diversity estimates from these 84 ancient Chinook salmon were compared to 379 contemporary samples. Our analysis provides the first direct measure of reduced genetic diversity for Chinook salmon from the ancient to the contemporary period, as measured both in direct loss of mitochondrial haplotypes and reductions in haplotype and nucleotide diversity. However, these losses do not appear equal across the basin, with higher losses of diversity in the mid-Columbia than in the Snake subbasin. The results are unexpected, as the two groups were predicted to share a common history as parts of the larger Columbia River Basin, and instead indicate that Chinook salmon in these subbasins may have divergent demographic histories.

Dataset Information

Evaluating the Potential Fitness Effects of Chinook Salmon (Oncorhynchus tshawytscha) Aquaculture Using Non-Invasive Population Genomic Analyses of MHC Nucleotide Substitution Spectra.

Publications

Evaluating the Potential Fitness Effects of Chinook Salmon (<i>Oncorhynchus tshawytscha</i>) Aquaculture Using Non-Invasive Population Genomic Analyses of MHC Nucleotide Substitution Spectra.

Similar Datasets

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