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TABLE 12.1 Fitness at 20°C of the 20°C-Selected Lineages and Their Historical Progenitors, Each Measured Relative to the Common Ancestor

 

−1

−2

−3

32

1.026 ± 0.050

1.081 ± 0.026

1.022 ± 0.019

32/20

1.124 ± 0.065

1.266 ± 0.076

1.121 ± 0.024

37

0.979 ± 0.045

0.997 ± 0.034

0.897 ± 0.042

37/20

1.072 ± 0.053

1.124 ± 0.080

1.050 ± 0.045

42

0.947 ± 0.061

1.005 ± 0.039

0.992 ± 0.059

42/20

1.019 ± 0.041

1.089 ± 0.089

1.128 ± 0.057

32–42

1.018 ± 0.035

1.085 ± 0.014

1.001 ± 0.035

32–42/20

1.143 ± 0.052

1.113 ± 0.039

1.191 ± 0.042

Rows are historical selective temperature regimes; columns are lineage designations (see Fig. 12.1). Entries are mean values ± 95% confidence limits, with n = 6 replicate fitness assays for each entry.

TABLE 12.2 Change in Fitness (ΔW) at 20°C of 20°C-Selected Lines Compared with Their Historical Progenitors

 

−1

−2

−3

32/20 vs. 32

0.098

0.185

0.099

 

P = 0.006

P < 0.001

P < 0.001

37/20 vs. 37

0.093

0.128

0.154

 

P = 0.003

P = 0.002

P < 0.001

42/20 vs. 42

0.073

0.084

0.136

 

P = 0.015

P = 0.025

P = 0.001

32-42/20 vs. 32-42

0.125

0.028

0.190

 

P < 0.001

P = 0.056

P < 0.001

Cell entries are changes in mean fitness from Table 12.1 and P values of one-tailed t tests.

Therefore, there was a general adaptation to selective temperature in this experiment, and this adaptation was also significantly manifest in >90% of the individual lineages. The mean fitness increment is not significantly different (P = 0.14) from that of six replicate lines selected at 20°C directly from Anc (Mongold et al., 1996).

Trade-Off at 40°C

Table 12.3 gives the relative fitness, measured at 40°C, of each lineage that evolved at 20°C and its immediate progenitor. The resulting change in fitness at 40°C (ΔW) is reported in Table 12.4. Changes in fitness (ΔW) were not significantly affected by historical environment (F3,20 = 0.282, P = 0.84).



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