the effect of flower position on variation and covariation in floral traits in a wild hermaphrodite plant花位置变化的影响以及相关变异在野生植物雌雄同体植物的特征.pdfVIP

Zhao et al. BMC Plant Biology 2010, 10:91 /1471-2229/10/91 R E S E A R C H A R T I C L E Open Access Research article The effect of flower position on variation and covariation in floral traits in a wild hermaphrodite plant 1,2 2 1 Zhi-Gang Zhao , Guo-Zhen Du* and Shuang-Quan Huang* Abstract Background: Floral traits within plants can vary with flower position or flowering time. Within an inflorescence, sexual allocation of early produced basal flowers is often female-biased while later produced distal flowers are male-biased. Such temporal adjustment of floral resource has been considered one of the potential advantages of modularity (regarding a flower as a module) in hermaphrodites. However, flowers are under constraints of independent evolution of a given trait. To understand flower diversification within inflorescences, here we examine variatio n and covariation in floral traits within racemes at the individual and the maternal family level respectively in an alpine herb Aconitum gymnandrum (Ranunculaceae). Results: We found that floral traits varied significantly with flower position and among families, and position effects were family-specific. Most of the variance of floral traits was among individuals rather than among flowers within individuals or among families. Significant phenotypic correlations between traits were not affected by position, indicating trait integration under shared developmental regulation. In contrast, positive family-mean correlations in floral traits declined gradually from basal to distal flowers (nine significant correlations among floral traits in basal flowers and only three in distal flowers), showing position-specificity. Therefore, the pattern and magnitude of genetic correlations decreased with flower p