Since the first introduction from North America more than a century ago, rainbow trout (Oncorhynchus mykiss) have rapidly established self-sustaining populations in major river basins of Patagonia. Many generations later, only the freshwater resident life history is expressed in the Chubut and Negro rivers of northern Argentinian Patagonia, whereas both the resident and anadromous life histories are found in the Santa Cruz River of southern Argentina. Despite previous studies that have tried to identify the sources of these introduced populations, uncertainty still exists.
View Article and Find Full Text PDFPopulations composed of individuals descended from multiple distinct genetic lineages often feature significant differences in phenotypic frequencies. We considered hatchery production of steelhead, the migratory anadromous form of the salmonid species and investigated how differences among genetic lineages and environmental variation impacted life history traits. We genotyped 23,670 steelhead returning to the four California Central Valley hatcheries over 9 years from 2011 to 2019, confidently assigning parentage to 13,576 individuals to determine age and date of spawning and rates of iteroparity and repeat spawning within each year.
View Article and Find Full Text PDFLife-history variation is the raw material of adaptation, and understanding its genetic and environmental underpinnings is key to designing effective conservation strategies. We used large-scale genetic pedigree reconstruction of anadromous steelhead trout (Oncorhynchus mykiss) from the Russian River, CA, USA, to elucidate sex-specific patterns of life-history traits and their heritability. SNP data from adults returning from sea over a 14-year period were used to identify 13,474 parent-offspring trios.
View Article and Find Full Text PDFHybridization between coastal cutthroat trout (Oncorhynchus clarkii clarkii) and steelhead (O. mykiss) was assessed in the Smith River, California. Individuals were categorized as pure or as 1 of 10 hybrid classes using 30 "diagnostic" single-nucleotide polymorphisms positioned on 26 separate chromosomes.
View Article and Find Full Text PDFGlobal fisheries kill millions of seabirds annually through bycatch, but little is known about population-level impacts, particularly in species that form metapopulations. U.S.
View Article and Find Full Text PDFInferring the genomic basis of local adaptation is a long-standing goal of evolutionary biology. Beyond its fundamental evolutionary implications, such knowledge can guide conservation decisions for populations of conservation and management concern. Here, we investigated the genomic basis of local adaptation in the Coho salmon (Oncorhynchus kisutch) across its entire North American range.
View Article and Find Full Text PDFNon-invasive monitoring was used to evaluate the concentrations of 40 contaminants in the blood plasma of the North American Green Sturgeon Acipenser medirostris caught and released from three estuaries in Washington State. The highest contaminant concentrations were found in fish caught in the most urbanized sites. Few statistical differences were found when evaluating contaminant levels according to sex, maturation stage, or distinct population segments of Green Sturgeon.
View Article and Find Full Text PDFGenetic changes underlying adaptation vary greatly in terms of complexity and, within the same species, genetic responses to similar selective pressures may or may not be the same. We examine both complex (supergene) and simple (SNP) genetic variants occurring in populations of rainbow trout (Oncorhynchus mykiss) independently isolated from ocean access and compared them to each other and to an anadromous below-barrier population representing their ancestral source to search for signatures of both parallel and nonparallel adaptation. All landlocked populations displayed an increased frequency of a large inversion on chromosome Omy05, while 3 of the 4 populations exhibited elevated frequencies of another inversion located on chromosome Omy20.
View Article and Find Full Text PDFUnderstanding the genetic basis of repeated evolution of the same phenotype across taxa is a fundamental aim in evolutionary biology and has applications in conservation and management. However, the extent to which interspecific life-history trait polymorphisms share evolutionary pathways remains underexplored. Here, we address this gap by studying the genetic basis of a key life-history trait, age at maturity, in four species of Pacific salmonids (genus Oncorhynchus) that exhibit intra- and interspecific variation in this trait-Chinook Salmon, Coho Salmon, Sockeye Salmon, and Steelhead Trout.
View Article and Find Full Text PDFDifferentiation between ecotypes is usually presumed to be complex and polygenic. Seasonal patterns of life history in salmon are used to categorize them into ecotypes, which are often considered "distinct" animals. Using whole-genome sequencing and tribal fishery sampling of Chinook salmon, we show that a single, small genomic region is nearly perfectly associated with spawning migration timing but not with adiposity or sexual maturity, traits long perceived as central to salmon ecotypes.
View Article and Find Full Text PDFA thorough reconstruction of historical processes is essential for a comprehensive understanding of the mechanisms shaping patterns of genetic diversity. Indeed, past and current conditions influencing effective population size have important evolutionary implications for the efficacy of selection, increased accumulation of deleterious mutations, and loss of adaptive potential. Here, we gather extensive genome-wide data that represent the extant diversity of the Coho salmon (Oncorhynchus kisutch) to address two objectives.
View Article and Find Full Text PDFIn temperate climates, the recurring seasonal exigencies of winter represent a fundamental physiological challenge for a wide range of organisms. In response, many temperate insects enter diapause, an alternative developmental program, including developmental arrest, that allows organisms to synchronize their life cycle with seasonal environmental variation. Geographic variation in diapause phenology contributing to local climatic adaptation is well documented.
View Article and Find Full Text PDFSecondary contact may have important implications for ecological and evolutionary processes; however, few studies have tracked the outcomes of secondary contact from its onset in natural ecosystems. We evaluated an anadromous alewife ( reintroduction project in Rogers Lake (Connecticut, USA), which contains a landlocked alewife population that was isolated as a result of colonial-era damming. After access to the ocean was restored, adult anadromous alewife were stocked into the lake.
View Article and Find Full Text PDFAn amendment to this paper has been published and can be accessed via a link at the top of the paper.
View Article and Find Full Text PDFMales and females often differ in their fitness optima for shared traits that have a shared genetic basis, leading to sexual conflict. Morphologically differentiated sex chromosomes can resolve this conflict and protect sexually antagonistic variation, but they accumulate deleterious mutations. However, how sexual conflict is resolved in species that lack differentiated sex chromosomes is largely unknown.
View Article and Find Full Text PDFMarine species with pelagic larvae typically exhibit little population structure, suggesting long-distance dispersal and high gene flow. Directly quantifying dispersal of marine fishes is challenging but important, particularly for the design of marine protected areas (MPAs). Here, we studied kelp rockfish (Sebastes atrovirens) sampled along ~25 km of coastline in a boundary current-dominated ecosystem and used genetic parentage analysis to identify dispersal events and characterize them, because the distance between sedentary parents and their settled offspring is the lifetime dispersal distance.
View Article and Find Full Text PDFFreshwater habitat alteration and marine fisheries can affect anadromous fish species, and populations fluctuating in size elicit conservation concern and coordinated management. We describe the development and characterization of two sets of 96 single nucleotide polymorphism (SNP) assays for two species of anadromous alosine fishes, alewife and blueback herring (collectively known as river herring), that are native to the Atlantic coast of North America. We used data from high-throughput DNA sequencing to discover SNPs and then developed molecular genetic assays for genotyping sets of 96 individual loci in each species.
View Article and Find Full Text PDFThe northern elephant seal, Mirounga angustirostris, was heavily hunted and declared extinct in the 19th century. However, a colony remained on remote Guadalupe Island, Mexico and the species has since repopulated most of its historical distribution. Here, we present a comprehensive evaluation of genetic variation in the species.
View Article and Find Full Text PDFClimate change is predicted to increase the frequency and intensity of extreme climate events. Tests on empirical data of theory-based predictions on the consequences of extreme climate events are thus necessary to understand the adaptive potential of species and the overarching risks associated with all aspects of climate change. We tested predictions on the genetic and life-history consequences of extreme climate events in two populations of marble trout Salmo marmoratus that have experienced severe demographic bottlenecks due to flash floods.
View Article and Find Full Text PDFThe streams draining of into San Francisco Bay, California, have been impacted by habitat alteration for over 150 years, and roads, dams, water diversions, and other impediments now block the paths of many aquatic migratory species. These changes can affect the genetic structure of fish populations, as well as driving adaptive evolution to novel environmental conditions. Here, we determine the evolutionary relationships of San Francisco Bay Area steelhead/rainbow trout () populations and show that (i) they are more closely related to native coastal steelhead than to the California Central Valley lineage, with no evidence of introgression by domesticated hatchery rainbow trout, (ii) populations above and below barriers within watersheds are each other's closest relatives, and (iii) adaptive genomic variation associated with migratory life-history traits in shows substantial evolutionary differences between fish above and below dams.
View Article and Find Full Text PDFConservation of the evolutionary legacy of endangered species is a key component for long-term persistence. Totoaba is a long-lived fish endemic to the Gulf of California and is considered critically endangered. There is currently a debate concerning its conservation status and whether it can be used as a fishery resource.
View Article and Find Full Text PDFExpression of phenotypic plasticity depends on reaction norms adapted to historic selective regimes; anthropogenic changes in these selection regimes necessitate contemporary evolution or declines in productivity and possibly extinction. Adaptation of conditional strategies following a change in the selection regime requires evolution of either the environmentally influenced cue (e.g.
View Article and Find Full Text PDFSalmonid fishes are cold water piscivores with a native distribution spanning nearly the entire temperate and subarctic northern hemisphere. Trout in the genus Oncorhynchus are the most widespread salmonid fishes and are among the most important fish species in the world, due to their extensive use in aquaculture and valuable fisheries. Trout that inhabit northwestern Mexico are the southernmost native salmonid populations in the world, and the least studied in North America.
View Article and Find Full Text PDFUnderstanding seasonal migration and localized persistence of populations is critical for effective species harvest and conservation management. Pacific salmon (genus Oncorhynchus) forecasting models predict stock composition, abundance, and distribution during annual assessments of proposed fisheries impacts. Most models, however, fail to account for the influence of biophysical factors on year-to-year fluctuations in migratory distributions and stock-specific survival.
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