Why are Arctic flowers so colorful? Reproductive ecology and selection on floral traits in the tundra plant Parrya nudicaulis (Brassicaceae).

摘要

Investment in flowers in high latitude regions has been historically viewed as an evolutionary holdover with tundra pollinators ineffective in their capacity to transfer pollen. Numerous reproductive patterns associated with alpine and arctic species, particularly mechanisms associated with reproductive assurance, are suggested to be driven by low pollinator effectiveness and high levels of pollen limitation. I studied the reproductive ecology of Parrya nudicaulis, a species with relatively large sexual reproductive investment and a range of floral pigmentation, in tundra habitats to estimate the degree of pollen limitation and selection on phenotypic floral traits. The plants are highly pollinator-dependent and pollen limitation was severe. Pollinators exhibited consistent positive selection on flower number and selection on all floral traits was stronger in a pollen limited environment. Despite the longstanding views of tundra flowers as superfluous, tundra pollinators are necessary for plant reproduction and exhibit selection on numerous floral traits in Parrya nudicaulis.