Kinship Analysis of Pacific Salmon: Insights Into Mating, Homing, and Timing of Reproduction (original) (raw)
Related papers
2015
In this paper, we assess the relationship between behavioural (social) and genetic mating success in sockeye salmon (Oncorhynchus nerka) and the frequency of multiple genetic partnering in both sexes. We introduced groups of 13 ripe adults (7 males, 6 females) into four spawning arenas in the Weaver Creek spawning channel, British Columbia, and monitored their behaviour until spawning was complete. Genetic fingerprints of adults and offspring were determined with microsatellites. Both males and females spawned with up to four different partners. Only 4 of 24 females mated predominantly with a single male. Behavioural measures of reproductive success in males (social dominance, time as consort, number of female partners) were strongly correlated with genetic reproductive success (proportion of offspring sired and number of females mated with) but explained only 33–40 % of the variance in reproductive success. Only longevity (spawning life index) was correlated with indices of female ...
Alternative Mating Strategies in Atlantic Salmon and Brown Trout
Journal of Heredity, 2001
By screening variable number of tandem repeat (VNTR) loci, multiple paternity within clutches has been found in wild populations of southern European Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). For Atlantic salmon, we determined the relative contribution of alternative male phenotypes to the next generation. Individual males that are morphologically juvenile yet sexually mature fertilized a large proportion of eggs, and they thereby contributed to an increase of genetic variability in wild populations via (1) balancing the sex ratio, (2) increasing outbreeding, and (3) enlarging the effective population size, in part a consequence of (1) and (2). In addition, these precocious males ensured that interspecific spawns involving Atlantic salmon females and brown trout males (a fairly common occurrence in southern Europe where the two species are sympatric) resulted mostly in Atlantic salmon progeny. For brown trout, preliminary genetic results indicated that multiple paternity, when present, was not due to alternative mating strategies by males, but rather to successive fertilizations by adult suitors.
Social versus genetic measures of reproductive success in sockeye salmon, Oncorhynchus nerka
2004
In this paper, we assess the relationship between behavioural (social) and genetic mating success in sockeye salmon (Oncorhynchus nerka) and the frequency of multiple genetic partnering in both sexes. We introduced groups of 13 ripe adults (7 males, 6 females) into four spawning arenas in the Weaver Creek spawning channel, British Columbia, and monitored their behaviour until spawning was complete. Genetic fingerprints of adults and offspring were determined with microsatellites. Both males and females spawned with up to four different partners. Only 4 of 24 females mated predominantly with a single male. Behavioural measures of reproductive success in males (social dominance, time as consort, number of female partners) were strongly correlated with genetic reproductive success (proportion of offspring sired and number of females mated with) but explained only 33-40% of the variance in reproductive success. Only longevity (spawning life index) was correlated with indices of female reproductive success. Behaviour provides a practical means to assess reproductive success in males but will underestimate the reproductive success of some subordinate males. Female reproductive success is more difficult to assess, because most females spawn all their eggs and there are no obvious behavioural or genetic attributes that can be used as indices of success.
Molecular Ecology, 1999
The major objective of this study was to test the hypothesis that juvenile Atlantic salmon kin occupy adjacent territories in their natural habitat in order to profit from the benefits associated with kin-biased behaviours, as has been observed under controlled laboratory conditions. Microsatellites were used to establish the relatedness of salmon fry (in their first summer of life) and parr (in their second and third summer of life) captured in adjacent territories. We did not observe a relationship between the proximity and the relatedness of either parr of the same cohort or fry in their natural habitat. Although many pairs of fry were identified as being related when sampled immediately after emergence, most family groups did not occupy adjacent territories. The high dispersal potential in rivers, the low occupation rate of the habitat and the incidence of half-sibs in nature most probably reduce the opportunity and advantage of kin-biased behaviour, in contrast to laboratory studies conducted in artificial, high-density conditions.
Integrative Organismal Biology, 2021
Captive breeding can affect how sexual selection acts on subsequent generations. One context where this is important is in fish hatcheries. In many salmon hatcheries, spawning is controlled artificially and offspring are reared in captivity before release into the wild. While previous studies have suggested that hatchery and natural origin fish may make different mate choice decisions, it remains to be determined how hatchery fish may be making different mate choice decisions compared to natural origin fish at a genetic level. Using genotyping-by-sequencing (GBS), we identify single nucleotide polymorphisms (SNPs) associated with variation in mate pairings from a natural context involving hatchery and natural origin coho salmon (Oncorhynchus kisutch). In both natural origin and hatchery mate pairs, we observed more SNPs with negative assortment, than positive assortment. However, only 3% of the negative assortment SNPs were shared between the two mating groups, and 1% of the positive assortment SNPs were shared between the two mating groups, indicating divergence in mating cues between wild and hatchery raised salmon. These findings shed light on mate choice in general and may have important implications in the conservation management of species as well as for improving other captive breeding scenarios. There remains much to discover about mate choice in salmon and research described here reflects our intent to test the potential of ongoing advances in population genomics to develop new hatchery practices that may improve the performance of hatchery offspring, lessening the differences and thus potential impacts upon wild stocks.
While nonanadromous males (stream-resident and/or mature male parr) contribute to reproduction in anadromous salmonids, little is known about their impacts on key population genetic parameters. Here, we evaluated the contribution of Atlantic salmon mature male parr to the effective number of breeders (Nb) using both demographic (variance in reproductive success) and genetic (linkage disequilibrium) methods, the number of alleles, and the relatedness among breeders. We used a recently published pedigree reconstruction of a wild anadromous Atlantic salmon population in which 2548 fry born in 2010 were assigned parentage to 144 anadromous female and 101 anadromous females that returned to the river to spawn in 2009 and to 462 mature male parr. Demographic and genetic methods revealed that mature male parr increased population Nb by 1.79 and 1.85 times, respectively. Moreover, mature male parr boosted the number of alleles found among progenies. Finally, mature male parr were in average less related to anadromous females than were anadromous males, likely because of asynchronous sexual maturation between mature male parr and anadromous fish of a given cohort. By increasing Nb and allelic richness, and by decreasing inbreeding, the reproductive contribution of mature male parr has important evolutionary and conservation implications for declining Atlantic salmon populations.
Conservation Genetics, 2008
Conservation programs that release captivebred individuals into the wild to mix with naturally produced individuals are an increasingly common method of supporting or enhancing weak or reduced populations that otherwise may not be self-sustaining. Captive and supportive breeding can be important conservation tools for species with small or declining populations; however, in the case of hatcheries producing salmonid fishes, detailed evaluation of spawning programs is rare. We examined variation in reproductive success, measured by adult offspring production, from three parental generations of hatchery-bred steelhead trout (Oncorhynchus mykiss) using an exclusion-based method of genetic parentage assignment. Reproductive success varied greatly among individuals (especially males) and was correlated with fecundity and maternal spawning date. Estimates of egg to smolt survival for the population as a whole among years ranged from 64% to 95%, marine survival ranged from 0.32% to 2.30%, and the number of adults produced per female ranged from 0 to 18 and the number of adults produced per male ranged from 0 to 32. The effective number of breeders ranged from 11% to 31% of the census population size for that brood year. These ratios fell within estimates from estimates of Ne/N in chinook (O. tshawytscha) and rainbow trout (O. mykiss) hatchery populations.
Molecular Ecology, 2010
Reproductive success and its determinants are difficult to infer for wild populations of species with no parental care where behavioural observations are difficult or impossible. In this study, we characterized the breeding system and provide estimates of individual reproductive success under natural conditions for an exhaustively sampled streamresident brown trout (Salmo trutta) population. We inferred parentage using a full probability Bayesian model that combines genetic (microsatellite) with phenotypic data. By augmenting the potential parents file with inferred parental genotypes from sib-ship analysis in cases where large families had unsampled parents, we could make more precise inference on variance of family size. We observed both polygamous and monogamous matings and large reproductive skew for both sexes, particularly in males. Correspondingly, we found evidence for sexual selection on body size for both sexes. We show that the mating system of brown trout has the potential to be very flexible and we conjecture that environmental uncertainty could be driving the evolution and perhaps select for the maintenance of plasticity of the mating system in this species.
Conservation …, 2008
The use of captive broodstocks is becoming more frequently employed as the number of species facing endangerment or extinction throughout the world increases. Efforts to rebuild the endangered Snake River sockeye salmon, Oncorhynchus nerka, population have been ongoing for over a decade, but the use of microsatellite data to develop inbreeding avoidance matrices is a more recent component to the program. This study used known genealogical relationships among sockeye salmon offspring to test four different pairwise relatedness estimators and a maximum-likelihood (M-L) relatedness estimator. The goal of this study was to develop a breeding strategy with these estimators that would minimize the loss of genetic diversity, minimize inbreeding, and determine how returning anadromous adults are incorporated into the broodstock along with full-term hatchery adults. Results of this study indicated that both the M xy and R QG estimators had the lowest Type II error rates and the M-L and R R estimators had the lowest Type I error rates. An approach that utilizes a combination of estimators may provide the most valuable information for managers. We recommend that the M-L and R R methods be used to rank the genetic importance of returning adults and the M xy or R QG estimators be used to determine which fish to pair for spawning. This approach provides for the best genetic management of this captive, endangered population and should be generally applicable to the genetic management of other endangered stocks with no pedigree.