Latitudinal trends in thermal safety margin and maximum warming tolerance.

<p>Thermal safety margins (<b>A–C</b>) and maximum warming tolerances (<b>D–F</b>) of the investigated <i>Paramecium caudatum</i> clones were calculated using habitat temperatures from global climate layers (<b>A</b>+<b>D</b>), near-by meteorological station data (<b>B</b>+<b>E</b>) and from climate change projections (<b>C</b>+<b>F</b>). Symbols represent the mean ± standard error of the mean. Latitudes of the European clones were corrected for altitude assuming a 100 km increase in latitude for a 100 m increase in altitude. Arrows indicate <i>P. caudatum</i> clones from high altitude (cf. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030598#pone-0030598-t001" target="_blank">Table 1</a>).</p

Latitude-dependent ecophysiology.

<p>Dependency between latitude and ecophysiological key characteristics: <b>A</b>) critical thermal minimum (<i>CT</i>_min), <b>B</b>) thermal optimum (<i>T</i>_opt) and <b>C</b>) critical thermal maximum (<i>CT</i>_max). Symbols represent the mean ± standard error of the mean derived from the nonlinear mixed-effects model <i>nm0a</i> with residual bootstrapping. Latitudes of the European <i>P. caudatum</i> clones were corrected for altitude assuming that 100 m elevation translates into a 100 km latitudinal increment within the temperate zone. Spearman's rank correlation coefficients and the respective <i>p</i>-values are as follows for the whole dataset (n = 18): <i>CT</i>_min (<i>r_s</i> = −0.795, <i>p</i><0.001), <i>T</i>_opt (<i>r_s</i> = −0.409, <i>p</i> = 0.092), <i>CT</i>_max (<i>r_s</i> = −0.596, <i>p</i><0.01); and for the European subset (n = 15): <i>CT</i>_min (<i>r_s</i> = −0.647, <i>p</i><0.01), <i>T</i>_opt (<i>r_s</i> = 0.027, <i>p</i> = 0.924), <i>CT</i>_max (<i>r_s</i> = −0.299, <i>p</i> = 0.279).</p

General shape of a thermal performance curve.

<p>Relationship between environmental temperature and a physiological rate of an ectotherm expressed as a thermal performance curve (grey line). The optimum temperature (<i>T</i>_opt) specifies the temperature at maximum performance. The ecophysiological key characteristics critical thermal minimum (<i>CT</i>_min) and maximum (<i>CT</i>_max) delimit an organism's thermal tolerance.</p

Origin of <i>Paramecium caudatum</i> clones, genetic background and GenBank® accession numbers.

*<p>following the COI haplotype determination of Barth et al. (2006).</p

Mantel test for the correlation between genetic (<i>x</i> matrix) and ecophysiological distances (<i>y</i> matrix).

<p><i>SSx</i> = sum of products of <i>x</i> matrix elements;</p><p><i>SSy</i> = sum of products of <i>y</i> matrix elements;</p><p><i>SPxy</i> = sum of cross products of corresponding elements of the <i>x</i> and <i>y</i> matrices;</p><p><i>Rxy</i> = Mantel correlation coefficient.</p

Thermal constraints.

<p><b>A</b>) Relationship between calculated optimum temperature (<i>T</i>_opt) and maximum growth rate (<i>μ</i>_{max, cal}) for all investigated <i>P. caudatum</i> clones supporting <i>warmer is better</i>. Symbols represent the mean ± standard error of the mean derived from the nonlinear mixed-effects model <i>nm0a</i> with residual bootstrapping. Significance was tested with Spearman's rank correlation (n = 18, <i>r_s</i> = 0.775, <i>p</i><0.001). <b>B</b>) Trade-off between calculated maximum growth rate (<i>μ</i>_{max, cal}) and thermal tolerance breadth (TTB = <i>CT</i>_max−<i>CT</i>_min). Symbols represent the mean ± standard error of the mean derived from the nonlinear mixed-effects model <i>nm0a</i> with residual bootstrapping. Significance was tested by using Spearman's rank correlation (n = 18, <i>r_s</i> = −0,554, <i>p</i><0.05).</p

Thermal performance curves.

<p>Fitted thermal performance curves using the <i>Lactin-2</i> model to describe the growth rates – temperature relationship of all investigated clonal <i>P. caudatum</i> cultures. Clones were arranged according to their geographic origin: <b>A</b>) Northern Europe, <b>B</b>) Central Europe, <b>C</b>) Southern Europe and <b>D</b>) Indonesia. Symbols represent the mean ± standard error of the mean (n = 3) of the determined growth rates at the respective temperatures. Lines define the fitted thermal performance curves. Clonal descriptions refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030598#pone-0030598-t001" target="_blank">Table 1</a>.</p

Ecophysiological characteristics of individual <i>Paramecium caudatum</i> clones and the two regions, Europe and Indonesia.

<p>For each <i>P. caudatum</i> clone, the calculated critical minimum (<i>CT</i>_min), maximum (<i>CT</i>_max) and optimum temperatures (<i>T</i>_opt) as well as the highest observed (<i>μ</i>_{max, obs}) and calculated growth rates (<i>μ</i>_{max, calc}) and thermal tolerance breadths (<i>TTB</i>) are reported as mean ± standard error of the mean.</p

<i>In silico</i> matching of the species-specific probes Fokinia_198, Fokinia_434 and Fokinia_1250 against bacterial SSU rRNA gene sequences available from RDP (release 11, update 4) and SILVA (release 123) databases.

<p>Number of sequences in the corresponding database was 3,333,501 (RDP) or 1,756,783 (SILVA). “mism” stands for “mismatch(es)”. Reported are the number of sequences (“hits”) which theoretically hybridize with the probe allowing for the given number of mismatches.</p

Bayesian inference phylogenetic tree built with MrBayes employing the GTR + I + G model.

<p>Numbers indicate bootstrap values inferred after 1,000 pseudoreplicates for maximum likelihood and Bayesian posterior probabilities (values below 70.0% and 0.7 are not shown). The sequence characterized in the present work is reported in bold. Scale bar: 9 nucleotide substitutions per 100 positions. “<i>Ca</i>.” stands for “<i>Candidatus</i>”.</p