The floral evolution of Ericales
Final Report Abstract
The aim of this project has been to better understand the evolution of the flower of Ericales an order of flowering plant comprising ~12,000 species. The order exhibits a notably high diversity of floral morphologies encompassing a wide variety of plants (e.g., kiwifruit, primroses, snapweed, heath, ebony, and brazil nuts). To better understand their floral evolution, I reconstruct likely ancestral flowers of the whole order, each comprising family, and wellsupported monophyletic groups of two or more families. To achieve this aim, I use morphological and genetic data from over 400 living species of Ericales and morphological data from 13 fossilised flower which have been assigned to Ericales. In the first part of the project, I found that different parts of the flower of Ericales and flowering plants evolve at different speeds. I divided the 35 morphological characters I used for the study into four depending on which of the developmental parts of the flower they belong to and estimated the evolutionary rate of each character. In both Ericales and flowering plants, characters associated with the androecium (pollen-producing part) evolve the fasted, whereas characters of the gynoecium (seed-producing part) evolve the slowest. Additionally, this led to the conclusion that structural characters evolve tend to be more conserved than characters associated with pollinator interaction. In the second part of the project, I aimed to reconstruct ancestral flowers of Ericales as outlined above. Because the position of the chosen fossils within the phylogenetic tree of Ericales contain a degree of uncertainty, chose a method to incorporate this uncertainty into the reconstruction of ancestral characters. In addition, I used two different statistical methods to infer the ancestral flowers to see if they infer congruent results. Both methods infer mostly congruent results for most of the characters used in the analyses. I found that the ancestral flower of Ericales is most likely bisexual with five fused petals and five sepals which a radially symmetric, and with four to five fused carpels. However, no clear results could be found for the number of fertile stamens of the ancestral flower of Ericales, one method inferred more that ancestral flower had more than ten stamens, whereas the other methods inferred five stamens. This difference influences the interpretation of the evolution of polystemony (possessing more stamens than petals and sepals), in one scenario polystemony would be ancestral being lost multiple times across the order, but in the other scenario polystemony would be gained multiple times independently within the order. In conclusion, the project gained valuable insight into the evolution of floral characters and was one of the first studies in plants to explicitly include fossils to reconstruct ancestral characters enhancing such an analysis because fossils may have character combinations that are no longer present in living plants.
Publications
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Profile of a flower: How rates of morphological evolution drive floral diversification in Ericales [Talk]. Australasian Systematic Botany Society: Student and Early Career Research Conference, Mt Annan, NSW, Australia.
Herting, Julian; Schönenberger, Jürg & Sauquet, Hervé
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Ancestral state reconstruction and the ancestral flower of Ericales (2023), invited guest lecture at the University of New England, Armidale, NSW, Australia
Herting, Julian Kevin
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Floral evolution in Ericales (2023), invited talk at Beadle Herbarium, University of New England, Armidale, NSW, Australia
Herting, Julian Kevin
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Profile of a flower: How rates of morphological evolution drive floral diversification in Ericales and angiosperms. American Journal of Botany, 110(8).
Herting, Julian; Schönenberger, Jürg & Sauquet, Hervé
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The ancestral flower of Ericales. Biosystematics 2023, Canberra, ACT, Australia.
Herting, Julian; Schönenberger, Jürg & Sauquet, Hervé
