Floral plasticity in an iteroparous plant: The interactive effects of genotype, environment, and ontogeny in Campanula rapunculoides (Campanulaceae)

Phenotypic variation in 11 floral and reproductive traits was studied in cl oned plants of Campanula rapunculoides replicated in three discrete environ ments. Using an ANOVA approach, we determined the relative influence of gen otype (G), environment (E), G x E interaction. and ontogeny (position on th e raceme) on the 11 traits. Two traits, duration of flowering and pollen si ze, showed no significant variation. All nine remaining traits had signific ant genotypic variation, accounting for 21-38% of the total phenotypic vari ation. Correlations among variant traits in seven genotypes were predominan tly positive, but several significant correlations in one environment chang ed sign or were nonsignificant in another environment. Ovule number was neg atively correlated with most male function traits: the negative correlation between ovule and pollen number was particularly strong and consistent acr oss environments. Six traits varied significantly across environments, incl uding number of flowers. number of ovules per flower. and duration of the m ale phase, but pollen traits did not show a significant environmental main effect. The G x E interaction was significant for Bower number. corolla siz e, nectar quality, duration of the male phase, pollen viability, and ovule number. The contribution of interaction variance to the total phenotypic va riation (5-14%) was comparable to that of the environment alone (7-21%). Ov ule number decreased in Rowers on the upper part of the raceme by nearly 25 %, but other traits did not vary significantly by floral position. These re sults suggest that (1) pollen traits are buffered against environmental cha nge more than ovule number or other floral characters. (2) a male-female tr ade-off exists and is complicated by ontogenic factors, (3) G x E interacti ons are common but may have small effects, and (4) specific correlation pat ter ns among floral traits can be dependent upon the environment under whic h they develop.