About this Research Topic
Angiosperms exhibit a wide range of variability in floral attributes such as shape, size or color. Color is one of the most conspicuous floral characters, and since Darwin’s time, it has been considered an important trait for pollinator attraction. However, over the past several decades, a growing body of evidence suggests the flower color is implied in angiosperm evolution through diverse ways.
The most prevalent and variable pigments that paint flowers are the anthocyanins, which originate from the anthocyanin biosynthetic pathway, highly conserved in angiosperms. Branches of this pathway produce other flavonoid compounds that protect plants against a variety of environmental stressors such as pathogens, herbivores, drought, extreme temperatures, UV radiation, etc. Thus, the presence of a certain floral color is usually accompanied by resistance to biotic and abiotic stresses due the presence of these secondary compounds. In addition, the color of the flowers has a very important effect on the attraction of pollinators. Different groups of pollinators, depending on their sensory abilities, can show innate preference for certain floral colors, exerting direct selective pressures on them and contributing to an increase of the fitness of those plants. For example, floral constancy of pollinators can limit the pollen flow between individual flowers with different colors causing assortative mating.
Flower color is a labile character; mutations in the anthocyanin biosynthetic pathway are frequent and often lead to evolutionarily significant flower color variants. The maintenance or loss of these new forms of color in the population depends on the selective pressures, which are often antagonistic to the preferences of pollinators. If the new color morphotype presents greater fitness than the original or simply it can remain in populations over years. If it confers some level of reproductive isolation, flower color can be implicated in the speciation process. Floral color has been considered as a "magic trait" in speciation and in fact, the evolutionary transitions of floral color are frequent within angiosperm clades and often associated with rapid diversification rates. Furthermore, it is recently proposed that the regulation of the biosynthetic pathway of floral pigment may be linked with those other secondary compound present in floral scent and nectar rewards.
This Research Topic aims to provide novel insights on how flower color can contribute to a better understanding of angiosperm evolution across multiple scales, from gene expression regulation to biochemical profiles, including quantification of flower color and pollinator perception in ecosystem dynamics. The main sub-topics are:
- Molecular basis of flower color variation (from gene expression, to regulatory networks)
- Floral color variation within the plant (color change during flower lifespan, variation in pigmentation associated with non-reproductive tissues)
- Intraspecific variation in flower color with special focus on color polymorphism (e.g., incipient speciation)
- Flower color and macroevolutionary phenomena (diversification, extinction, etc.)
- The role of floral color in pollination and species interactions at the community level
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