Phylogenetic trends and environmental correlates of nuclear genome size variation in Helianthus sunflowers.
Flowering plants serve as a powerful model for studying the evolution of nuclear genome size (GS) given the tremendous GS variation that exists both within and across angiosperm lineages. Helianthus sunflowers consist of c. 50 species native to North America that occupy diverse habitats and vary in ploidy level. In the current study, we generated a comprehensive GS database for 49 Helianthus species using flow cytometric approaches. We examined variability across the genus and present a comparative phylogenetic analysis of GS evolution in diploid Helianthus species. Results demonstrated that different clades of diploid Helianthus species showed evolutionary patterns of GS contraction, expansion and relative stasis, with annual diploid species evolving smaller GS with the highest rate of evolution. Phylogenetic comparative analyses of diploids revealed significant negative associations of GS with temperature seasonality and cell production rate, indicating that the evolution of larger GS in Helianthus diploids may be more permissible in habitats with longer growing seasons where selection for more rapid growth may be relaxed. The Helianthus GS database presented here and corresponding analyses of environmental and phenotypic correlates will facilitate ongoing and future research on the ultimate drivers of GS evolution in this well-studied North American plant genus.
['Qiu|Fan|F|', 'Baack|Eric J|EJ|0000-0002-2492-8546', 'Whitney|Kenneth D|KD|0000-0002-2523-5469', 'Bock|Dan G|DG|0000-0001-7788-1705', 'Tetreault|Hannah M|HM|0000-0001-5911-7316', 'Rieseberg|Loren H|LH|0000-0002-2712-2417', 'Ungerer|Mark C|MC|']
D002467:Cell Nucleus D004171:Diploidy D004777:Environment D014644:Genetic Variation D059646:Genome Size D018745:Genome, Plant D006368:Helianthus D016018:Least-Squares Analysis D010802:Phylogeny D012044:Regression Analysis
Helianthus temperature seasonality growing season genome size (GS) evolution phylogenetic comparative analysis