Flower Color Evolution In Rhyncholotus

Lotus section Rhyncholotus comprises four species endemic to the islands of Tenerife and La Palma in the Canary Islands. The group has several features associated with a bird pollination syndrome. Flowers are large compared with their bee-pollinated ancestors; they produced large amount of nectar composed mainly of simple sugars (hexoses) and the four species display flowers with colors that range from orange to red. Current field work observations report two passerine birds, Phylloscopus canariensis and Parus caerolus, as the major pollinators in these Lotus species. The pollination syndrome in this group is described as pollination by opportunistic passerine birds that occasionally feed on these flowers. Beside these bird species, individuals of the lizard Gallotia galloti have been also reported feeding in at least two species of this group.

Red/orange bird pollinated species evolved within a group of yellow bee-pollinated species that have the ability to modify flower color after anthesis, as an aid to increase foraging efficiency. These flower change fromyellow to orange, pink, red, bron and purple. These yellow bee-pollinated species have the abitlity to produce the anthocyanin present in the bird pollinated species.


Flower color variation within Macaronesian Lotus. Top row: Lotus berthelotii, L. campylocladus, post-changed flowers of L. eriosolen (brown) and L. emeroides. Bottom row: L. pyranthus, post-changed flowers of L. glaucus (orange), L. jacobaeus (purple) and L. sessilifolius (red).

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