Abstract Detail



Macroevolution

Gallagher, Megan [1], Sapir, Yuval [2], Imbert, Eric [3].

How natural selection drives and maintains floral colour variation: irises, pollinators and beyond.

Close your eyes and think of your favorite flower. What is its colour? Chances are that immediately you thought on one specific colour. Indeed, most flower populations bear uniform flower colour, believed to be the outcome of pollinator-mediated directional selection. Flower colour serves as a visual signal for the pollinators that learn to associate it with reward, and in turn, exert selection on it. Most flowering plant species bear monomorphic flower colour, although some exhibit colour dimorphism or polymorphism, and in rare cases even a continuous scale of colours. While the genetic basis of flower colour polymorphism is known, the balance between mutation and selection, and whether this balance drives within-population polymorphism, has rarely studied. Pollinator-mediated selection can drive fixation of one colour, but other selection agents, such as pathogens or climate, as well as disassortative behavior of the pollinators, can increase fitness of multiple colours and maintain colour polymorphism. We studied selection on flower colour in three taxa of irises: in the colour dimorphic Iris lutescensselection on flower colour was not pollinator-mediated, while in the polymorphic I. pumilaselection on one colour morph only was mediated by pollinators. Selection on flower colour in the Royal Irises (section Oncocyclus) was found to be weak and not pollinator-mediated, while expression of colour genes varied much. We suggest that mutation-selection balance is a key to understand patterns of flower colour variation or its lack.


1 - Tel Aviv University, School of Plant Sciences & Food Security, George Wise Faculty of Life Science, Tel Aviv University, Tel Aviv-Yafo, 69978, Israel
2 - Tel Aviv University Botanical Garden, Tel Aviv University, Ramat Aviv, Tel Aviv University, Ramat Aviv, Tel Aviv, 69978, Israel
3 - Université de Montpellier, Institut des Sciences de l’Évolution Montpellier (ISEM)

Keywords:
Pollination
flower color
Polymorphism
evolution
Selection.

Presentation Type: Oral Paper
Number:
Abstract ID:553
Candidate for Awards:None


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