Figure 1.
Major life-history traits and their effect on fitness in annual plant species.
Green triangle: plant, yellow circle: seed, green sector: conditions favourable for growth, grey sector: adverse conditions. Red arrows show the participation of each trait to lifetime fitness, via their effect on survival, resource acquisition or fecundity.
Figure 2.
Location of origin the 112 European genotypes used in this study.
Figure 3.
Histograms showing natural genetic variation of life history traits using adjusted means.
(a) Primary dormancy (days): measured by number of days required to reach 50% of germination (DSDS50). (b) Secondary dormancy (% of germination decrease per day): measured by the reduction in germination rate of fully after-ripened seed after a 6-week long exposure to 4°C in darkness. (c) Vegetative growth rate (cm2/day): measured by increase of leaf area during one week in the greenhouse. (d) Flowering time (days): number of days until opening of the first flower.
Table 1.
ANOVA table reporting significant effect of the genotype on phenotypic variance for each life-history traits and associating broad-sense heritability H2.
Figure 4.
Life history traits as a function of the gradients in latitude (expressed in °North) and/or population structure (measured as the relative contribution to the first population structure group).
Only significant effects reported in Table 2 are shown with the percentage of variance explained associated. (a) Latitude has a significant effect on primary dormancy and flowering time, p<0.05 and p<0.001, respectively. (b) Population structure estimated by the probability to belong to one of the two clusters, has a significant effect on primary and secondary dormancy, p<0.01 and p<0.1, respectively.
Table 2.
Multi- and uni-variate analyses of life-history variation, p-values associated with the effects of latitude and population structure.
Figure 5.
Flowering time as a function of vegetative growth rate.
The 112 European genotypes were divided in three categories: low (blue dots), medium (green dots) and high primary seed dormancy level (red dots).
Table 3.
Pearson correlation coefficients between life history traits (112 genotypes).
Table 4.
Pairs of trait with a latitudinal gradient of co-variation.
Figure 6.
Pairwise trait correlation between primary dormancy, flowering time or growth rate change significantly along the latitudinal gradient.
The correlation coefficient r (−1<r<1), on the y-axis, was calculated along a sliding latitudinal window with a fixed number of 45 genotypes. The average latitude of each 45-genotype window is given on the x-axis. Red points show local r values with associated p<0.05. The change in pairwise trait correlation r with latitude was quantified by the regression coefficient R2, and its associated p-value (see methods). With the exception of (d), results hold when sliding windows encompass 25 or 30 genotypes.