scholarly journals Neutral genetic variation in adult Chinook salmon ( Oncorhynchus tshawytscha ) affects brain-to-body trade-off and brain laterality

2017 ◽  
Vol 4 (12) ◽  
pp. 170989 ◽  
Author(s):  
Mallory L. Wiper ◽  
Sarah J. Lehnert ◽  
Daniel D. Heath ◽  
Dennis M. Higgs
Keyword(s):  
Genetic Variation ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Directional Asymmetry ◽  
Trade Offs ◽  
Neutral Genetic Variation ◽  
Low Levels ◽  
Inbreeding Level ◽  
The Right ◽  
The Brain

Low levels of heterozygosity can have detrimental effects on life history and growth characteristics of organisms but more subtle effects such as those on trade-offs of expensive tissues and morphological laterality, especially of the brain, have not been explicitly tested. The objective of the current study was to investigate how estimated differences in heterozygosity may potentially affect brain-to-body trade-offs and to explore how these heterozygosity differences may affect differential brain growth, focusing on directional asymmetry in adult Chinook salmon ( Oncorhynchus tshawytscha ) using the laterality and absolute laterality indices. Level of inbreeding was estimated as mean microsatellite heterozygosity resulting in four ‘inbreeding level groups’ (Very High, High, Medium, Low). A higher inbreeding level corresponded with a decreased brain-to-body ratio, thus a decrease in investment in brain tissue, and also showed a decrease in the laterality index for the cerebellum, where the left hemisphere was larger than the right across all groups. These results begin to show the role that differences in heterozygosity may play in differential tissue investment and in morphological laterality, and may be useful in two ways. Firstly, the results may be valuable for restocking programmes that wish to emphasize brain or body growth when crossing adults to generate individuals for release, as we show that genetic variation does affect these trade-offs. Secondly, this study is one of the first examinations to test the hypothesized relationship between genetic variation and laterality, finding that in Chinook salmon there is potential for an effect of inbreeding on lateralized morphology, but not in the expected direction.

Early experience and reproductive morph both affect brain morphology in adult male Chinook salmon (Oncorhynchus tshawytscha)

2014 ◽  
Vol 71 (9) ◽  
pp. 1430-1436 ◽  
Author(s):  
Mallory L. Wiper ◽  
Stephanie Britton ◽  
Dennis M. Higgs
Keyword(s):  
Chinook Salmon ◽  
Habitat Complexity ◽  
Oncorhynchus Tshawytscha ◽  
Driving Forces ◽  
Brain Size ◽  
Brain Regions ◽  
Brain Morphology ◽  
Short Term ◽  
Trade Offs ◽  
The Difference

It is clear that brain size and structure can be greatly influenced by the environment, and in fish, factors such as habitat complexity, rearing environment, and reproductive status have been shown to affect brain morphology and behaviour, but it is unclear how long these effects last. The objective of the current study was to investigate variability in overall brain size and particular brain regions of male Chinook salmon (Oncorhynchus tshawytscha) through the evaluation of potential driving forces — environment and reproductive morph. By comparing fish from different rearing environments and different male reproductive morphs (hooknose versus jack), the current research assessed the influence of each of these factors on overall brain size and on select brain regions. Male hooknose salmon had relatively smaller brains, once corrected for body size, than male jack salmon, suggesting possible trade-offs between somatic and brain development. Fish reared in hatchery environments but released into the wild as presmolts still had relatively larger brains than their wild counterparts, despite sharing wild habitats for over 3 years, suggesting persistent effects of hatchery rearing. Taken together, these results show that the difference in reproductive morphs can substantially impact brain morphology and that short-term environmental influences can have persistent effects throughout ontogeny.

Genetic variation in freshwater survival and growth of chinook salmon (Oncorhynchus tshawytscha)

Aquaculture ◽  
1987 ◽  
Vol 64 (2) ◽  
pp. 85-96 ◽  
Author(s):  
R.E. Withler ◽  
W.C. Clarke ◽  
B.E. Riddell ◽  
H. Kreiberg
Keyword(s):  
Genetic Variation ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Survival And Growth

Heritability of fluctuating asymmetry for multiple traits in chinook salmon (Oncorhynchus tshawytscha)

2000 ◽  
Vol 57 (11) ◽  
pp. 2186-2192 ◽  
Author(s):  
Colleen A Bryden ◽  
Daniel D Heath
Keyword(s):  
Fluctuating Asymmetry ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Multiple Traits ◽  
Stress Indicator ◽  
Significant Heritability ◽  
The Individual ◽  
The Right ◽  
Genetic Contributions ◽  
Gill Raker

The heritability of fluctuating asymmetry (FA) as an indicator of developmental instability is of interest to evolutionary and conservation biologists and is the subject of ongoing controversy. This study examined the inheritance of FA in two groups of fish: domestic chinook salmon (Oncorhynchus tshawytscha) mated in a full-sib design and domestic and wild chinook salmon mated in a half-sib design. Eight traits were measured on the right and left sides of each fish: eye diameter, head length, maxillary length, branchiostegal ray number, pectoral and pelvic fin ray number, and upper and lower gill raker number on the first gill arch. Narrow-sense heritabilities were calculated from parent-offspring regressions for the first group and using sib analysis for the second group. Our data represent the largest breeding program designed to detect heritability of FA in fish reported to date. We found no significant heritability of FA for any of the individual traits examined or for a composite FA index. Our results indicate that FA estimates in chinook salmon will not be confounded by appreciable additive genetic contributions and thus can be reliably used as an environmental and genetic stress indicator.

Assessing developmental errors in branchiostegal rays as indicators of chronic stress in two species of Pacific salmon

2003 ◽  
Vol 81 (11) ◽  
pp. 1876-1884 ◽  
Author(s):  
W Bruce Campbell
Keyword(s):  
Kidney Disease ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Linear Models ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Ambient Temperatures ◽  
Bacterial Kidney Disease ◽  
Significant Difference ◽  
Low Levels

Stress during ontogeny reduces homeostasis, increasing the formation of developmental errors. Fused and partial branchiostegal rays were assessed as indicators of stress throughout embryogenesis in coho salmon (Oncorhy nchus kisutch Walbaum) and chinook salmon (Oncorhynchus tshawytscha Walbaum). Error frequencies and the proportion of fish possessing them should increase when development is stressed. Coho parr were examined from reciprocal crosses between two hatchery stocks experiencing artificially fluctuated (between 7 and 12 °C) or ambient (natural) temperatures throughout embryogenesis. Temperature means and ranges were equivalent between treatments, allowing patterns of thermal variance to be compared. Chinook presmolts, having high versus low levels of infection with bacterial kidney disease owing to similar levels of parental infection, also were examined. Sampled fish were cleared and stained and the errors analyzed using categorical linear models and observations of positional distributions. Although partial rays in coho were genetically influenced, fusion frequency increased significantly under fluctuating (551) versus ambient temperatures (163), as did the number of fish with fusions (207 versus 104, respectively). No significant difference between bacterial kidney disease groups was observed, indicating the disease had little influence over error development. Positional distributions of fused rays were bimodal in both species, showing anterior and posterior zones of weaker developmental control. Partial rays occurred at initial and terminal positions in the series, suggesting evolutionary vestigialization in both species. Branchiostegal ray fusions are shown to be useful traits for further investigation of thermal stress during embryogenesis in salmon.

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