The Relationship Of Low Genome Size, Annual Life History And Selfing

DC Albach and J Greilhuber

Institut für Botanik der Universität Wien, Rennweg 14, A-1030 Wien, Austria
Back to Kews Plant Genome Size Meeting Papers

Abstract


    The amount of DNA per chromosome set is fairly constant within species, but its inter-specific variation is enormous. However, the biological significance of this variation is little understood. Most authors assume a "nucleotypic" effect, an inherent effect of DNA based on its simple mass, besides its genic effect. However, rigorous phylogenetic analyses to distinguish between direct causal connections and chance correlation in smaller taxa are extremely rare. We analysed genome size estimates for 42 members of Veroniceae in connection with results from a phylogenetic analysis of plastid trnL-F DNA sequences and tested correlations using standard statistical tests, phylogenetically independent contrasts and a model-based generalised least squares method to distinguish the phylogenetic effect on the results. The long-debated correlation of low genome size with annual life history is not significant (p = 0.12) using standard statistical tests and independent contrasts but only with the generalised least squares method (p < 0.01). However, there seems to be a lower upper limit in annuals than in perennials. The correlations found in earlier studies could also be due to a significant correlation of a low genome size with a selfing breeding system, which is probably due to fewer transposable elements in selfers. Reasons for these correlations found and those not found are discussed.