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Modularity and evolution of flower shape: the role of function, development, and spandrels in Erica
Author(s) -
Reich Dieter,
Berger Andreas,
Balthazar Maria,
Chartier Marion,
Sherafati Mahboubeh,
Schönenberger Jürg,
Manafzadeh Sara,
Staedler Yannick M.
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16337
Subject(s) - modularity (biology) , pollinator , biology , pollination , evolutionary biology , parallel evolution , generalist and specialist species , selection (genetic algorithm) , pollen , ecology , phylogenetics , computer science , artificial intelligence , genetics , habitat , gene
Summary Flowers have been hypothesized to contain either modules of attraction and reproduction, functional modules (pollination‐effecting parts) or developmental modules (organ‐specific). Do pollination specialization and syndromes influence floral modularity? In order to test these hypotheses and answer this question, we focused on the genus Erica : we gathered 3D data from flowers of 19 species with diverse syndromes via computed tomography, and for the first time tested the above‐mentioned hypotheses via 3D geometric morphometrics. To provide an evolutionary framework for our results, we tested the evolutionary mode of floral shape, size and integration under the syndromes regime, and – for the first time – reconstructed the high‐dimensional floral shape of their most recent common ancestor. We demonstrate that the modularity of the 3D shape of generalist flowers depends on development and that of specialists is linked to function: modules of pollen deposition and receipt in bird syndrome, and access‐restriction to the floral reward in long‐proboscid fly syndrome. Only size and shape principal component 1 showed multiple‐optima selection, suggesting that they were co‐opted during evolution to adapt flowers to novel pollinators. Whole floral shape followed an Ornstein–Uhlenbeck (selection‐driven) evolutionary model, and differentiated relatively late. Flower shape modularity thus crucially depends on pollinator specialization and syndrome.