Genetic diversity and evolutionary history of four closely related <italic>Aquilegia</italic> species revealed by 10 nuclear gene fragments.

Abstract: The genus <italic>Aquilegia</italic> is emerging as the new model system for plant development, ecology, and evolution studies. Previous research showed that pollinator shift might drive the diversification of North American <italic>Aquilegia</italic> species, and natural selection on the length of petal nectar spur might play a crucial role. In this genus, <italic>A. ecalcarata</italic> Maxim. is the only taxon that has lost nectar spurs. Previous phylogenetic results indicated that <italic>A. ecalcarata</italic>, <italic>A. yabeana</italic> Kitag., <italic>A. oxysepala</italic> var. <italic>kansuensis</italic> Bruhl., and <italic>A. rockii</italic> Munz comprised a monophyletic group. However, their pattern of genetic diversity remains unknown. In addition, little is known about the evolutionary relationship among the four species on the population level. We carried out a population genetics study with 21 representative populations based on 10 single‐copy nuclear gene fragments and found that: (i) <italic>A. yabeana</italic> conserved the highest genetic diversity (both <italic>π</italic>_sil and <italic>θ</italic>_sil) and <italic>A. oxysepala</italic> var. <italic>kansuensis</italic> had the lowest level; (ii) <italic>A. ecalcarata</italic> split into two groups, with one population clustered with <italic>A. rockii</italic> and the other five populations clustered with <italic>A. oxysepala</italic> var. <italic>kansuensis</italic>; and (iii) the allele frequency spectrum showed an excess of low frequency alleles in all four species, implying that they may undergo the mutation‐drift equilibrium. Our findings provide the first investigation of genetic diversity and evolutionary relationships in <italic>A. yabeana</italic>, <italic>A. oxysepala</italic> var. <italic>kansuensis</italic>, <italic>A. rockii</italic>, and <italic>A. ecalcarata</italic>. They lay the foundation for future evolutionary studies, such as speciation mediated by pollinators. [ABSTRACT FROM AUTHOR]