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Abstract Detail


Sharber, Wyatt [1], Whitlock, Barbara [2].

Parallel evolution of trithecate anthers in Ayenia and Megatritheca (Malvaceae; Byttnerioideae).

The evolution of stamen number and morphology is quite labile across Angiosperms; however, the number of thecae and their containing microsporangia is highly conserved, with few deviations in the dithecate, tetrasporangiate anther form. The Malvaceae is one of the few families that show deviations in thecae number, with dithecate, monothecate, and trithecate anthers. Here I investigate two taxa with rare and highly unusual trithecate anthers, Ayenia and Megatritheca (Byttnerioideae). Using a newly generated molecular phylogeny of these taxa and ancestral character state reconstruction, I show that trithecate anthers evolved in parallel in these taxa, while closely related taxa, Byttneria and Rayleya, retained the ancestral dithecate form. Trithecate anthers are associated with larger overall flowers. However, the large flowers of Megatritheca are the result of a decrease in size from its dithecate ancestor, whereas the large flowers of Ayenia represent an increase in size. Anthers of Megatritheca have increased in size by an increase in height, as well as the addition of a theca. Anthers and thecae of Ayenia, in contrast, have decreased in size in most measurements. Ancestral area reconstruction supports a South American origin for Ayenia, Byttneria, and Rayleya, with multiple dispersals to the Old World tropics in Byttneria. Finally, I discuss the taxonomic implications of my phylogenetic analyses, and propose a recircumscription of Byttneria to reflect monophyletic evolutionary lineages.

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1 - 1537 Garcia Ave., Coral Gables, FL, 33146, United States
2 - University Of Miami, Department Of Biology, P.O. Box 249118, Coral Gables, FL, 33124, United States

Floral evolution

Presentation Type: Oral Paper
Session: 26, ASPT Cooley Awards II
Location: 110/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 1:45 PM
Number: 26002
Abstract ID:805
Candidate for Awards:George R. Cooley Award

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