Text here is modified from the supplementary information of Thomas et al. (2012):
We assembled a data set containing growth rate measurements of marine and estuarine phytoplankton at different temperatures that have been published over the past century. Where data were available only in the form of graphs, they were digitized using the program g3data.
Several criteria were used to determine the inclusion of species/strain data in our dataset.
1) To facilitate comparisons across studies we only included data for growth rates measured in units that could be converted to specific growth rate.
2) Because we were primarily concerned with estimating the temperature at which strains/species achieve their maximum growth rates, we rejected data from thermal reaction norms where the largest measured growth rate occurred at the lowest or highest temperature considered.
3) Published reaction norms with fewer than four measured growth rates were excluded, as were curves showing strong bimodality, which we attributed to imprecise experimental measurements.
4) Where multiple published reaction norms on the same isolate existed and were measured under different experimental conditions (salinity, nutrient limitation, light levels, day length), we preferentially selected ones meeting the following conditions:
a. Salinity between 30 and 40 parts per thousand.
b. Light levels greater than or equal to 100 microeinsteins.m-2.s-1.
c. Not experimentally limited by nutrients
d. Day lengths of greater than or equal to 10 hours.
When no reaction norms for a particular isolate satisfied these experimental constraints, we settled for using data from the curve(s) that were closest to the desired light and salinity levels.
5) We considered only marine and estuarine strains not isolated from inland waters.
After applying these criteria, we had data for a total of 194 isolates/strains belonging to approximately 130 species, from 111 unique isolation locations ranging in latitude from 76°N to 75°S.
Related Reference:
Thomas, M. K., Kremer, C. T., Klausmeier, C. A., & Litchman, E. (2012). A global pattern of thermal adaptation in marine phytoplankton. Science, 338(6110), 1085-1088. DOI: 10.1126/science.1224836.
Supplemental materials: http://www.sciencemag.org/content/suppl/2012/10/25/science.1224836.DC1/Thomas.SM.pdf
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