DOI: 10.5061/dryad.p0g4v
title: Data from: Responses to simulated winter conditions differ between threespine stickleback ecotypes

description: Abiotic factors can act as barriers to colonization and drive local
 adaptation. During colonization, organisms may cope with changes in
 abiotic factors using existing phenotypic plasticity, but the role of
 phenotypic plasticity in assisting or hindering the process of local
 adaptation remains unclear. To address these questions, we explore the
 role of winter conditions in driving divergence during freshwater
 colonization and the effects of plasticity on local adaptation in
 ancestral marine and derived freshwater ecotypes of threespine stickleback
 (Gasterosteus aculeatus). We found that freshwater-resident stickleback
 had greater tolerance of acute exposure to low temperatures than marine
 stickleback, but these differences were abolished after acclimation to
 simulated winter conditions (9L:15D photoperiod at 4°C). Plasma chloride
 levels differed between the ecotypes, but showed a similar degree of
 plasticity between ecotypes. Gene expression of the epithelial calcium
 channel (ECaC) differed between ecotypes, with the freshwater ecotype
 demonstrating substantially greater expression than the marine ecotype,
 but there was no plasticity in this trait under these conditions in either
 ecotype. In contrast, growth (assessed as final mass) and the expression
 of an isoform of the electroneutral Na+/H+ exchanger (NHE3) exhibited
 substantial change with temperature in the marine ecotype that was not
 observed in the freshwater ecotype under the conditions tested here, which
 is consistent with evolution of these traits by a process such as genetic
 assimilation. These data demonstrate substantial divergence in many of
 these traits between freshwater and marine stickleback, but also
 illustrate the complexity of possible relationships between plasticity and
 local adaptation.
description: Critical thermal minimum
 (CTmin) of threespine sticklebackLaboratory determined
 critical thermal minimum (CTmin). Fish are lab reared crosses of fish from
 Paxton Lake (Lake) and Oyster Lagoon (Marine), British Columbia and their
 hybrids (Hybrid).CTmin_data.csvMortality data for laboratory reared threespine sticklebackEcotypes are fish from Oyster Lagoon (M), Paxton Lake (F), and their hybrids (H). Temp = rearing temperature (degrees C). Total Fish = starting number of fish from a given family in a specific tank. Mortalities = total number of fish that died from a given family in a specific tank over the course of the full experiment.fish_mortalities_data.csvPlasma chloride concentration of laboratory reared threespine sticklebackThreespine stickleback were reared at a salinity of 2 ppt at either 4 or 14 degrees C. Ecotypes used were from Oyster Lagoon (M), Paxton Lake (L), and their hybrids (H). Plasma chloride (Cl-) concentration is reported in mM.Plasma_chloride_data.csvmRNA levels for ion transporters in the gills of laboratory reared threespine sticklebackmRNA levels were measured using qRT-PCR in threespine stickleback from Oyster Lagoon (Marine), Paxton Lake (Lake), and their hybrids (Hybrid). The following genes were assessed: sodium hydrogen exchanger isoform 2 (NHE2), sodium hydrogen exchanger isoform 3 (NHE3), epithelial calcium channel (ECaC), V-Type ATPase isoform 1 (V Type 1), V-Type ATPase isoform 2 (V Type 2), and the sodium-potassium ATPase alpha subunit, variant 203 (NKA 203). Expression is normalized to the geometric mean of three control genes.qPCR_data.csv