No evidence for large differences in genomic methylation between wild and hatchery steelhead (Oncorhynchus mykiss)

2010 ◽  
Vol 67 (2) ◽  
pp. 217-224 ◽  
Author(s):  
Michael S. Blouin ◽  
Virginie Thuillier ◽  
Becky Cooper ◽  
Vindhya Amarasinghe ◽  
Laura Cluzel ◽  
...  
Keyword(s):  
Oncorhynchus Mykiss ◽  
Length Polymorphism ◽  
Fragment Length Polymorphism ◽  
Adult Offspring ◽  
Epigenetic Changes ◽  
Domestication Selection ◽  
Two Generations ◽  
In The Wild ◽  
Genomic Methylation ◽  
Epigenetic Processes

When salmonid fish that have been raised in hatcheries spawn in the wild, they often produce fewer surviving adult offspring than wild fish. Recent data from steelhead ( Oncorhynchus mykiss ) in the Hood River (Oregon, USA) show that even one or two generations of hatchery culture can result in dramatic declines in fitness. Although intense domestication selection could cause such declines, it is worth considering alternative explanations. One possibility is heritable epigenetic changes induced by the hatchery environment. Here, we show, using methylation-sensitive amplified fragment length polymorphism, that hatchery and wild adult steelhead from the Hood River do not appear to differ substantially in overall levels of genomic methylation. Thus, although altered methylation of specific DNA sites or other epigenetic processes could still be important, the hatchery environment does not appear to cause a global hypo- or hypermethylation of the genome or create a large number of sites that are differentially methylated.

Differential reproductive success of sympatric, naturally spawning hatchery and wild steelhead trout (Oncorhynchus mykiss) through the adult stage

2003 ◽  
Vol 60 (4) ◽  
pp. 433-440 ◽  
Author(s):  
Jennifer E McLean ◽  
Paul Bentzen ◽  
Thomas P Quinn
Keyword(s):  
Reproductive Success ◽  
Oncorhynchus Mykiss ◽  
Adult Stage ◽  
Poor Performance ◽  
Adult Offspring ◽  
Steelhead Trout ◽  
Freshwater Environment ◽  
Domestication Selection ◽  
In The Wild ◽  
Differential Reproductive Success

We used multilocus microsatellite analysis to compare the reproductive success of naturally spawning wild steelhead trout (Oncorhynchus mykiss) with a newly established sympatric hatchery population in Forks Creek, Washington, U.S.A. Hatchery steelhead spawning in the wild had markedly lower reproductive success than native wild steelhead. Wild females that spawned in 1996 produced 9 times as many adult offspring per capita as did hatchery females that spawned in the wild. Wild females that spawned in 1997 produced 42 times as many adult offspring as hatchery females. The wild steelhead population more than met replacement requirements (approximately 3.7–6.7 adult offspring were produced per female), but the hatchery steelhead were far below replacement requirements (<0.5 adults per female). The survival differential was greatest in the freshwater environment (i.e., production of seaward-migrating juveniles), but survival at sea favored the hatchery population in 1 year and the wild population in the next. The poor performance of the hatchery population may be a consequence of spawning too early in the winter, generations of inadvertent domestication selection, or a combination of these two.

scholarly journals Polyploid formation in cotton is not accompanied by rapid genomic changes

Genome ◽  
2001 ◽  
Vol 44 (3) ◽  
pp. 321-330 ◽  
Author(s):  
B Liu ◽  
C L Brubaker ◽  
G Mergeai ◽  
R C Cronn ◽  
J F Wendel
Keyword(s):  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Amplified Fragment Length Polymorphism ◽  
Aflp Analysis ◽  
Epigenetic Changes ◽  
Selfed Progeny ◽  
Genomic Changes ◽  
Allopolyploid Speciation ◽  
Polyploid Formation

Recent work has demonstrated that allopolyploid speciation in plants may be associated with non-Mendelian genomic changes in the early generations following polyploid synthesis. To address the question of whether rapid genomic changes also occur in allopolyploid cotton (Gossypium) species, amplified fragment length polymorphism (AFLP) analysis was performed to evaluate nine sets of newly synthesized allotetraploid and allohexaploid plants, their parents, and the selfed progeny from colchicine-doubled synthetics. Using both methylation-sensitive and methylation-insensitive enzymes, the extent of fragment additivity in newly combined genomes was ascertained for a total of approximately 22 000 genomic loci. Fragment additivity was observed in nearly all cases, with the few exceptions most likely reflecting parental heterozygosity or experimental error. In addition, genomic Southern analysis on six sets of synthetic allopolyploids probed with five retrotransposons also revealed complete additivity. Because no alterations were observed using methylation-sensitive isoschizomers, epigenetic changes following polyploid synthesis were also minimal. These indications of genomic additivity and epigenetic stasis during allopolyploid formation provide a contrast to recent evidence from several model plant allopolyploids, most notably wheat and Brassica, where rapid and unexplained genomic changes have been reported. In addition, the data contrast with evidence from repetitive DNAs in Gossypium, some of which are subject to non-Mendelian molecular evolutionary phenomena in extant polyploids. These contrasts indicate polyploid speciation in plants is accompanied by a diverse array of molecular evolutionary phenomena, which will vary among both genomic constituents and taxa.Key words: polyploidy, genome evolution, cotton, Gossypium, amplified fragment length polymorphism (AFLP).

The effects of high rearing density on the potential for domestication selection in hatchery culture of steelhead (Oncorhynchus mykiss)

2015 ◽  
Vol 72 (12) ◽  
pp. 1829-1834 ◽  
Author(s):  
Neil F. Thompson ◽  
Michael S. Blouin
Keyword(s):  
Oncorhynchus Mykiss ◽  
Fork Length ◽  
High Density ◽  
High Survival ◽  
Environment Interaction ◽  
Family Selection ◽  
Probability Of Survival ◽  
Reduced Body ◽  
Domestication Selection ◽  
In The Wild

Hatchery-reared steelhead (Oncorhynchus mykiss) often have lower fitness than natural-origin fish when spawning in the wild. Fitness loss in hatcheries is partly due to genetic adaptation to captivity (domestication), but the underlying selection pressures driving adaptation remain unknown. Circumstantial evidence suggests that adaptation to hatcheries is accelerated when fish are reared at high density. We hypothesized two mechanisms by which high rearing densities could accelerate adaptation to the hatchery. First, high density could increase the among-family component of variation in fork length, which could increase the opportunity for selection after release. Second, a growth trade-off in fork length among families could occur across densities (family-by-environment interaction). We raised the same set of families, in replicate, at each of two densities. We found main effects of density (high density reduced body size) and family (accounted for 33%–53% of variance in size at release) on juvenile fork length. However, high density did not increase the percentage of variance in fork length among families, and there was weak evidence for a family-by-environment interaction. We propose an alternate model of how increased density might exacerbate domestication selection. The relationship between size at release and probability of survival is strongly nonlinear (almost truncational) for steelhead. Because high density decreases the fork lengths of all families approximately equally, high density could simply reduce the number of families that are above a threshold for high survival, resulting in strong among-family selection after release from the hatchery.

Sign in / Sign up

Export Citation Format

Share Document