Global distribution and evolutionary transitions of floral symmetry in angiosperms

Abstract

Floral symmetry plays an important role in plant-pollinator interactions and may have remarkable impacts on angiosperm diversification. However, spatiotemporal patterns in floral symmetry and drivers of these patterns remain unknown. Here, using newly compiled floral symmetry (actinomorphy versus zygomorphy) data of 279,877 angiosperm species and their distributions and phylogenies, we estimated global geographic patterns and macroevolutionary dynamics of floral symmetry. We found that frequency of actinomorphic species increased with latitude, while that of zygomorphic species decreased. Solar radiation, present-day temperature, and Quaternary temperature change correlated with geographic variation in floral symmetry frequency. Evolutionary transitions from actinomorphy to zygomorphy dominated floral symmetry evolution, although the transition rate decreased with decreasing paleotemperature throughout the Cenozoic. Notably, we found that zygomorphy may not favor diversification of angiosperms as previously observed in some clades. Our study demonstrates the influence of (paleo)climate on spatiotemporal patterns in floral symmetry and challenges previous views about role of flower symmetry in angiosperm diversification.

Zygomorphic flowers last longer: the evolution of floral symmetry and floral longevity

“…Zygomorphy has evolved at least 154 times from actinomorphic ancestors and is currently found in at least 32 orders and 110 families of angiosperms [ 13 , 17 , 22 ]. The macroevolution of floral longevity has been less well described to date, but our phylogenetic exploration confirms previously noted patterns (e.g.…”

“…We assess these hypotheses in an evolutionary framework, given the strong phylogenetic signal of both floral symmetry and floral longevity, and provide one of the first descriptions of the evolutionary patterns of floral longevity across angiosperms as a whole. For completeness, we also assess whether the effect of symmetry on longevity is independent of the effect of latitude, given recent findings of longer floral longevity [ 3 ] and a higher frequency of actinomorphic species [ 17 ] at higher latitudes.…”

Visual-, Olfactory-, and Nectar-Taste-Based Flower Aposematism

“…Symmetry is a basic characteristic of flowers and inflorescences [116][117][118][119]. It was proposed that symmetry increases the efficiency of visual aposematic animal displays [120][121][122].…”