These data are described in detail in Sotka et al., 2018. From May until October 2015, we collected live thalli at each of 40 populations: 15 Japanese (six source and nine nonsource), five western North American, 10 eastern North American, and 10 European populations. We exposed a haphazardly chosen set of approximately 20 thalli per population to extreme heat (1, 2, and 4 hr in 40\u00b0C), extreme cold (45, 75, and 105 min at \u221220\u00b0C), and low salinities (8 days at 0, 5, and 10 ppt). For the heat tolerance assay, four apices per thallus were individually placed into unsealed 2- ml microcentrifuge tubes containing 175 \u03bcl of seawater. A control apex was kept in a 15\u00b0C growth chamber, while three apices were placed in a 40\u00b0C water bath for 1, 2, and 4 hr. For the cold tolerance assay, four apices were independently placed into sealed 250 \u03bcl PCR tubes containing 200 \u03bcl seawater. A control apex was kept in a 15\u00b0C incubator, while three apices were placed in a \u221220\u00b0 C freezer for 45, 75, and 105 min. Apices were then placed into randomly assigned wells of 12- well tissue culture plates (2.21- cm- diameter wells) filled with 4 ml of seawater and incubated at 15\u00b0C for 8 days with a 12- hr light/dark cycle. For the salinity tolerance assay, four apices were independently placed directly into the 12- well tissue culture plates filled with 4 ml of seawater at a titration of salinities diluted to 0, 5, and 10 ppt, with 30 ppt serving as a control. Every 2 days for 8 days, we changed water and assessed thallus bleaching (i.e., loss of photosynthetic pigments; Figure S2) as a proxy of mortality, itself an important component of fitness. We generated a Bleaching Score (BS), where \u201c1\u201d indicated no bleaching, \u201c2\u201d indicated partial bleaching or color change to pink or white, and \u201c3\u201d indicated full bleaching.
Bleaching scores of introduced seaweed when stressed by heat, cold, or low salinity.
BCO-DMO Data Processing Notes:
\n-Reformatted column names to comply with BCO-DMO standards