Salmon hatchery strays can demographically boost wild populations at the cost of diversity: quantitative genetic modelling of Alaska pink salmon.

Hatcheries are vital to many salmon fisheries, with inherent risks and rewards. While hatcheries can increase the returns of adult fish, the demographic and evolutionary consequences for natural populations interacting with hatchery fish on spawning grounds remain unclear. This study examined the impacts of stray hatchery-origin pink salmon on natural population productivity and resilience.

Assortative mating for reproductive timing affects population recruitment and resilience in a quantitative genetic model.

Quantitative models that simulate the inheritance and evolution of fitness-linked traits offer a method for predicting how environmental or anthropogenic perturbations can affect the dynamics of wild populations. Random mating between individuals within populations is a key assumption of many such models used in conservation and management to predict the impacts of proposed management or conservation actions. However, recent evidence suggests that non-random mating may be underestimated in wild populations and play an important role in diversity-stability relationships.

Genomic and phenotypic effects of inbreeding across two different hatchery management regimes in Chinook salmon.

Genomic approaches permit direct estimation of inbreeding and its effect on fitness. We used genomic-based estimates of inbreeding to investigate their relationship with eight adult traits in a captive-reared Pacific salmonid that is released into the wild. Estimates were also used to determine whether alternative broodstock management approaches reduced risks of inbreeding.

Local adaptation of phenology revealed in outcrosses between spawning segments of a salmonid population.

Local adaptation has been demonstrated in spatially or temporally distant animal populations but seldom in proximate populations. To address the scale of local adaptation in Pacific salmon (Oncorhynchus spp.), two generations of hybrids between temporally separated spawning segments were made in a population of pink salmon (O.

Genomewide association analyses of fitness traits in captive-reared Chinook salmon: Applications in evaluating conservation strategies.

A novel application of genomewide association analyses is to use trait-associated loci to monitor the effects of conservation strategies on potentially adaptive genetic variation. Comparisons of fitness between captive- and wild-origin individuals, for example, do not reveal how captive rearing affects genetic variation underlying fitness traits or which traits are most susceptible to domestication selection. Here, we used data collected across four generations to identify loci associated with six traits in adult Chinook salmon () and then determined how two alternative management approaches for captive rearing affected variation at these loci.

Mapping of quantitative trait loci for temporal growth and age at maturity in coho salmon: Evidence for genotype-by-sex interactions.

Phenotypic differences between males and females are ubiquitous throughout the animal kingdom. Therefore, investigating the extent to which sex-dependent genetic effects contribute to phenotypic variation is important in understanding the evolutionary response of each sex to natural and artificial selection. Sex-specific differences in growth patterns and age at sexual maturity have been observed in a number of anadromous salmonid fishes.

Evaluating the Ryman-Laikre effect for marine stock enhancement and aquaculture.

The Ryman-Laikre (R-L) effect is an increase in inbreeding and a reduction in total effective population size ( ) in a combined captive-wild system, which arises when a few captive parents produce large numbers of offspring. To facilitate evaluation of the R-L effect for scenarios that are relevant to marine stock enhancement and aquaculture, we extended the original R-L formula to explicitly account for several key factors that determine , including the numbers of captive and wild adults, the ratio of captive to wild (), productivity of captive and wild breeders, and removal of individuals from the wild for captive breeding. We show how to provide quantitative answers to questions such as: What scenarios lead to no loss of effective size? What is the maximum effective size that can be achieved? and What scenarios insure that will be no smaller than a specified value? Important results include the following: (1) For large marine populations, the value of becomes increasingly important as the captive contribution increases.

Effectiveness of managed gene flow in reducing genetic divergence associated with captive breeding.

Captive breeding has the potential to rebuild depressed populations. However, associated genetic changes may decrease restoration success and negatively affect the adaptive potential of the entire population. Thus, approaches that minimize genetic risks should be tested in a comparative framework over multiple generations.

Quantitative genetics of migration-related traits in rainbow and steelhead trout.

Rainbow trout (Oncorhynchus mykiss) exhibit remarkable life history diversity throughout their native range, and among the most evident is variation in migratory propensity. Although some populations and ecotypes will remain resident in freshwater habitats throughout their life history, others have the ability to undertake tremendous marine migrations. Those that migrate undergo a suite of behavioral, morphological, and physiological adaptations in a process called smoltification.

Comparative mapping between Coho Salmon (Oncorhynchus kisutch) and three other salmonids suggests a role for chromosomal rearrangements in the retention of duplicated regions following a whole genome duplication event.

Whole genome duplication has been implicated in evolutionary innovation and rapid diversification. In salmonid fishes, however, whole genome duplication significantly pre-dates major transitions across the family, and re-diploidization has been a gradual process between genomes that have remained essentially collinear. Nevertheless, pairs of duplicated chromosome arms have diverged at different rates from each other, suggesting that the retention of duplicated regions through occasional pairing between homeologous chromosomes may have played an evolutionary role across species pairs.

Genetic variation in bacterial kidney disease (BKD) susceptibility in Lake Michigan Chinook Salmon and its progenitor population from the Puget Sound.

Mass mortality events in wild fish due to infectious diseases are troubling, especially given the potential for long-term, population-level consequences. Evolutionary theory predicts that populations with sufficient genetic variation will adapt in response to pathogen pressure. Chinook Salmon Oncorhynchus tshawytscha were introduced into Lake Michigan in the late 1960s from a Washington State hatchery population.

Temporal variation in selection on body length and date of return in a wild population of coho salmon, Oncorhynchus kisutch.

Background: A number of studies have measured selection in nature to understand how populations adapt to their environment; however, the temporal dynamics of selection are rarely investigated. The aim of this study was to assess the temporal variation in selection by comparing the mode, direction and strength of selection on fitness-related traits between two cohorts of coho salmon (Oncorhynchus kisutch). Specifically, we quantified individual reproductive success and examined selection on date of return and body length in a wild population at Big Beef Creek, Washington (USA).

Simulating fishery-induced evolution in chinook salmon: the role of gear, location, and genetic correlation among traits.

Adaptation to human-modified ecosystems has been implicated in changing the life history of a number of wild animal populations, potentially contributing to their collapse. Fishing may be an important evolutionary force that can change the distribution of fitness-related traits; however, the magnitude and direction of the evolutionary response may be influenced by different management strategies. Most phenotypic traits subject to human-induced selection are simultaneously influenced by the environment and by genetic variation, and many traits are genetically correlated.

Clock polymorphism in Pacific salmon: evidence for variable selection along a latitudinal gradient.

Seasonal timing of life-history events is often under strong natural selection. The Clock gene is a central component of an endogenous circadian clock that senses changes in photoperiod (day length) and mediates seasonal behaviours. Among Pacific salmonids (Oncorhynchus spp.

Phenotypic plasticity and population viability: the importance of environmental predictability.

Phenotypic plasticity plays a key role in modulating how environmental variation influences population dynamics, but we have only rudimentary understanding of how plasticity interacts with the magnitude and predictability of environmental variation to affect population dynamics and persistence. We developed a stochastic individual-based model, in which phenotypes could respond to a temporally fluctuating environmental cue and fitness depended on the match between the phenotype and a randomly fluctuating trait optimum, to assess the absolute fitness and population dynamic consequences of plasticity under different levels of environmental stochasticity and cue reliability. When cue and optimum were tightly correlated, plasticity buffered absolute fitness from environmental variability, and population size remained high and relatively invariant.

Quantifying six decades of fishery selection for size and age at maturity in sockeye salmon.

Life history traits of wild animals can be strongly influenced, both phenotypically and evolutionarily, by hunting and fishing. However, few studies have quantified fishery selection over long time periods. We used 57 years of catch and escapement data to document the magnitude of and trends in gillnet selection on age and size at maturity of a commercially and biologically important sockeye salmon stock.

Human-induced evolution caused by unnatural selection through harvest of wild animals.

Human harvest of phenotypically desirable animals from wild populations imposes selection that can reduce the frequencies of those desirable phenotypes. Hunting and fishing contrast with agricultural and aquacultural practices in which the most desirable animals are typically bred with the specific goal of increasing the frequency of desirable phenotypes. We consider the potential effects of harvest on the genetics and sustainability of wild populations.

Estimates of natural selection in a salmon population in captive and natural environments.

Captive breeding is a commonly used strategy for species conservation. One risk of captive breeding is domestication selection--selection for traits that are advantageous in captivity but deleterious in the wild. Domestication selection is of particular concern for species that are bred in captivity for many generations and that have a high potential to interbreed with wild populations.

Evolutionary consequences of fishing and their implications for salmon.

We review the evidence for fisheries-induced evolution in anadromous salmonids. Salmon are exposed to a variety of fishing gears and intensities as immature or maturing individuals. We evaluate the evidence that fishing is causing evolutionary changes to traits including body size, migration timing and age of maturation, and we discuss the implications for fisheries and conservation.

Pacific salmon extinctions: quantifying lost and remaining diversity.

Widespread population extirpations and the consequent loss of ecological, genetic, and life-history diversity can lead to extinction of evolutionarily significant units (ESUs) and species. We attempted to systematically enumerate extinct Pacific salmon populations and characterize lost ecological, life history, and genetic diversity types among six species of Pacific salmon (Chinook [Oncorhynchus tshawytscha], sockeye [O. nerka], coho [O.