DOI: 10.5061/dryad.hj797
title: Data from: Shifting thresholds: rapid evolution of migratory life histories in steelhead/rainbow trout, Oncorhynchus mykiss

description: Expression of phenotypic plasticity depends on reaction norms adapted to
 historic selective regimes; anthropogenic changes in these selection
 regimes necessitate contemporary evolution or declines in productivity and
 possibly extinction. Adaptation of conditional strategies following a
 change in the selection regime requires evolution of either the
 environmentally influenced cue (e.g., size-at-age) or the state (e.g.,
 size threshold) at which an individual switches between alternative
 tactics. 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. We
 created 9 families and 917 offspring from 14 parents collected from the
 above- and below-barrier populations. After 1 year of common
 garden-rearing above-barrier offspring were 11% smaller and 32% lighter
 than below-barrier offspring. Using a novel analytical approach, we
 estimate that the mean size at which above-barrier fish switch between the
 resident and migrant tactic is 43% larger than below-barrier fish. As a
 result, above-barrier fish were 26% less likely to express the migratory
 tactic. Our results demonstrate how rapid and opposing changes in
 size-at-age and threshold size contribute to the contemporary evolution of
 a conditional strategy and indicate that migratory barriers may elicit
 rapid evolution toward the resident life history on timescales relevant
 for conservation and management of conditionally migratory species.
description: READMEREADME file for the four
 data files.smolt-dataOffspring data is in ‘smolt-data.csv’ as follows: Column 1: PIT: Passive Integrated Transponder number used for individual ID Column 2: FL: Fork length in mm Column 3: mass: in grams Column 4: Sex: Male, Female, or NA (i.e. failed to assign) Column 5: cross: AA or BB (i.e. pure above-barrier cross or pure below-barrier cross) Column 6: Ma: Individual ID of mother Column 7: MOM: A or B (origin of Ma) Column 8: Pa: Individual ID of father Column 9: DAD: A or B (origin of Pa) Column 10: score: smolt condition: 1, 2, 3, 4, or NA (see explanation below) Column 11: smolt: 0 or 1 (non-smolt or smolt)egg-dataEgg size and number data is in ‘egg-data.csv’ as follows: Column 2: MA: Individual ID of mother Column 3: ORIGIN: A or B (i.e. Above- or Below-barrier) Column 4: EGG_NO: total number of eggs in clutch Column 5: EGG_SIZE: in mmmovement-datamovement-data.csv Column 1: PIT: Passive Integrated Transponder number used for individual ID Column 2: cross: AxA, BxB, Hybrid, AxF1, BxF1, F1 (The latter four crosses are from a separate study not discussed in the corresponding manuscript. They were raised in the same manner as the AxA and BxB crosses discussed in the corresponding manuscript) Column 3: FL: Fork length in mm Column 4: mass: in grams Column 5: score: 1, 2, 3, 4 or NA (see explanation below) Column 6: smolt: 0 or 1 (i.e. non-smolt or smolt) Column 7: detect: 0 or 1 (i.e. not detected or detected)saltwater-challenge-dataData from the seawater challenge experiment are in saltwater-challenge-data.csv as follows: Column 1: PIT: Passive Integrated Transponder number used for individual ID Column 2: cross: AxA, BxB, Hybrid, AxF1, BxF1, F1 (The latter four crosses are from a separate study not discussed in the corresponding manuscript. They were raised in the same manner as the AxA and BxB crosses discussed in the corresponding manuscript) Column 3: FL: Fork length in mm Column 4: mass: in grams Column 5: score: 1, 2, 3, 4 or NA (see explanation below) Column 6: smolt: 0 or 1 (non-smolt or smolt) Column 7: sex: Male, Female, or NA (i.e. failed to assign) Column 8: fate: 0 or 1: (i.e. dead or alive at the end of the experiment) Column 9: Date: date individual was declared dead Column 10: Time: time individual was declared dead