scholarly journals Shifting thresholds: rapid evolution of migratory life histories in steelhead/rainbow trout, Oncorhynchus mykiss

2014 ◽  
Author(s):  
Corey Phillis ◽  
Jonathan W Moore ◽  
Mathieu Buoro ◽  
Sean Hayes ◽  
Carlos Garza ◽  
...  
Keyword(s):  
Growth Rate ◽  
Oncorhynchus Mykiss ◽  
Life Histories ◽  
Rapid Evolution ◽  
Common Garden ◽  
Source Population ◽  
Contemporary Evolution ◽  
Conditional Strategy ◽  
Threshold Size ◽  
Rainbow Trout Oncorhynchus Mykiss

Expression of phenotypic plasticity depends on reaction norms adapted to historic selective regimes; anthropogenic changes in these selection regimes necessitate contemporary evolution or extirpation. Adaptation of conditional strategies following a change in the selection regime requires evolution of either the environmentally influenced cue (e.g. growth rate) or the state (e.g. size threshold) at which an individual switches between conditional strategies. Using a population of steelhead (Oncorhynchus mykiss) introduced above a barrier waterfall in 1910, we evaluate how the conditional strategy to migrate evolves in response to selection against migration. Common garden-raised offspring of parents from the above-barrier population were 11% smaller and 31% lighter than offspring of parents from the below-barrier source population. Using a novel analytical approach we estimate that the mean size at which above-barrier fish switch between the resident and migrant strategy is 43% larger than below-barrier fish. As a result, above-barrier fish were 30% less likely to express the migratory strategy. Our results demonstrate how rapid and opposing changes in growth rate and threshold size contribute to the contemporary evolution of a conditional strategy and indicate that migratory barriers may elicit rapid evolution towards the resident life-history on timescales relevant for conservation and management of conditionally migratory species.

scholarly journals Shifting thresholds: rapid evolution of migratory life histories in steelhead/rainbow trout, Oncorhynchus mykiss

2014 ◽  
Author(s):  
Corey Phillis ◽  
Jonathan W Moore ◽  
Mathieu Buoro ◽  
Sean Hayes ◽  
Carlos Garza ◽  
...  
Keyword(s):  
Growth Rate ◽  
Oncorhynchus Mykiss ◽  
Life Histories ◽  
Rapid Evolution ◽  
Common Garden ◽  
Source Population ◽  
Contemporary Evolution ◽  
Conditional Strategy ◽  
Threshold Size ◽  
Rainbow Trout Oncorhynchus Mykiss

Expression of phenotypic plasticity depends on reaction norms adapted to historic selective regimes; anthropogenic changes in these selection regimes necessitate contemporary evolution or extirpation. Adaptation of conditional strategies following a change in the selection regime requires evolution of either the environmentally influenced cue (e.g. growth rate) or the state (e.g. size threshold) at which an individual switches between conditional strategies. Using a population of steelhead (Oncorhynchus mykiss) introduced above a barrier waterfall in 1910, we evaluate how the conditional strategy to migrate evolves in response to selection against migration. Common garden-raised offspring of parents from the above-barrier population were 11% smaller and 31% lighter than offspring of parents from the below-barrier source population. Using a novel analytical approach we estimate that the mean size at which above-barrier fish switch between the resident and migrant strategy is 43% larger than below-barrier fish. As a result, above-barrier fish were 30% less likely to express the migratory strategy. Our results demonstrate how rapid and opposing changes in growth rate and threshold size contribute to the contemporary evolution of a conditional strategy and indicate that migratory barriers may elicit rapid evolution towards the resident life-history on timescales relevant for conservation and management of conditionally migratory species.

scholarly journals Shifting Thresholds: Rapid Evolution of Migratory Life Histories in Steelhead/Rainbow Trout,Oncorhynchus mykiss

2015 ◽  
Vol 107 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Corey C. Phillis ◽  
Jonathan W. Moore ◽  
Mathieu Buoro ◽  
Sean A. Hayes ◽  
John Carlos Garza ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Life Histories ◽  
Rapid Evolution ◽  
Rainbow Trout Oncorhynchus Mykiss

scholarly journals Over the Falls? Rapid Evolution of Ecotypic Differentiation in Steelhead/Rainbow Trout (Oncorhynchus mykiss)

2009 ◽  
Vol 100 (5) ◽  
pp. 515-525 ◽  
Author(s):  
Devon E. Pearse ◽  
Sean A. Hayes ◽  
Morgan H. Bond ◽  
Chad V. Hanson ◽  
Eric C. Anderson ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Rapid Evolution ◽  
Ecotypic Differentiation ◽  
Rainbow Trout Oncorhynchus Mykiss

Individual variation and interrelationships between swimming performance, growth rate, and feeding in juvenile rainbow trout (Oncorhynchus mykiss)

1998 ◽  
Vol 55 (7) ◽  
pp. 1583-1590 ◽  
Author(s):  
T Ryan Gregory ◽  
Chris M Wood
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Plasma Cortisol ◽  
Positive Relationship ◽  
Swimming Performance ◽  
Individual Performance ◽  
Significant Positive Relationship ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss

Variation among individuals in specific growth rate (SGR), feeding, and two measures of swimming performance and their possible interrelationships were investigated in juvenile rainbow trout (Oncorhynchus mykiss) kept in groups on either satiation or half-satiation rations. Maximum sustainable velocity (Ucrit) was measured as an index of aerobic swimming performance and stamina (fatigue time in a fixed-velocity test at 6 body lengths ·s-1) as an index of anaerobic performance. Individual performance in both of these tests was found to be significantly repeatable. Trout fed on half-satiation ration exhibited significantly lower mean values of SGR and body size and higher levels of aggression-related fin damage, but no significant differences in stamina, relative or absolute Ucrit, glycogen content, or plasma cortisol. However, in these fish, there was a significant negative relationship between SGR and relative Ucrit, a significant positive relationship between SGR and stamina, and a significant positive relationship between SGR and total daily meal. None of these relationships were seen in fish fed to satiation. Plasma cortisol and tissue glycogen stores were not related to SGR. These results indicate that under the intensified competition of restricted ration, there are trade-offs between growth, feeding, and different types of swimming performance.

RNA/DNA ratios in white muscle as estimates of growth in rainbow trout held at different temperatures

1990 ◽  
Vol 68 (7) ◽  
pp. 1494-1498 ◽  
Author(s):  
Moira M. Ferguson ◽  
Roy G. Danzmann
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
White Muscle ◽  
Specific Growth ◽  
Fish Size ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Different Temperatures ◽  
Specific Growth Rates ◽  
Rna And Dna

The concentrations of RNA, DNA, and protein in white muscle from 240 uniquely tagged rainbow trout (Oncorhynchus mykiss) held at three temperatures (5, 8 (control), and 11 °C) were measured. Both RNA and RNA/DNA ratios were better predictors of recent length- and weight-specific growth rates than they were of absolute fish size. Furthermore, RNA concentrations were better predictors of growth than RNA/DNA ratios. The strength of the regression between either RNA/DNA ratio or RNA and growth rate did not differ consistently among temperatures. Fish reared at warmer temperatures had lower concentrations of RNA for both a given growth rate and a given DNA concentration compared with cold-reared trout. Warm-reared fish also had lower concentrations of DNA and higher protein/DNA ratios than cold-reared trout when fish size was standardized. The concomitant decrease in both RNA and DNA concentrations resulted in marginally lower RNA/DNA ratios in warm-reared fish.

Hybridization with Domesticated Rainbow Trout (Oncorhynchus mykiss) Reduces Seasonal Variation in Growth of Steelhead Trout (O. mykiss)

1993 ◽  
Vol 50 (3) ◽  
pp. 480-487 ◽  
Author(s):  
Jörgen I. Johnsson ◽  
W. Craig Clarke ◽  
Ruth E. Withler
Keyword(s):  
Growth Rate ◽  
Seasonal Variation ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Natural Waters ◽  
Salt Water ◽  
Feeding Activity ◽  
Steelhead Trout ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Winter Conditions

We tested the hypothesis that hybridization with domesticated rainbow trout (Oncorhynchus mykiss) reduces the seasonal variation in growth in both fresh and salt water in anadromous steelhead trout (O. mykiss). The seasonal variation in freshwater growth was more pronounced in the steelhead trout than in the hybrid and domesticated trout. Consequently, differences in growth rate among groups were considerably higher during winter than in fall or spring. We suggest that high feeding activity during unfavourable winter conditions in natural waters is maladaptive, but is not selected against in protected hatchery environments with a continuous food supply. This may lead to genetic divergence in feeding physiology and/or behaviour between steelhead trout and domesticated rainbow trout. Growth rates in experimental groups transferred to seawater in December relative to groups transferred in April were faster in rainbow and hybrid trout than in steelhead trout. The results support the hypothesis that seasonal variation in seawater growth in steelhead trout is reduced by crossing with domesticated rainbow trout.

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