Abstract Detail



Evolutionary Developmental Biology (Evo-Devo)

Appleton, Andrea [1], Schenk, John [2].

The Evolution and Development of Staminodes in Paronychia (Caryophyllaceae).

The variation in structures and functions of staminodes when compared across angiosperms suggests complex evolutionary processes underlie their origins, but to understand how and why these processes occur, comparative studies are needed in groups of closely related species. We used Paronychia (Caryophyllaceae) as a model system to compare the evolution and development of staminodes across closely related species within a genus. Staminodial structures in Paronychia have been referred to as both petals and staminodes, creating uncertainty regarding their organ identity. When surveyed across the genus, these structures differ morphologically and are absent in some species. We tested the hypotheses that these structures are (1) petals, or (2) staminodes. If the latter hypothesis was supported, we further hypothesized that staminodes are either vestigial or co-opted for a novel function. We evaluated the developmental series of North American species of Paronychia with scanning electron and light microscopy and conducted ancestral state estimations across phylogenies to infer when staminodes evolved. The staminodes developed between the outer androecial whorl and the carpel, indicating that they are derived from stamens. In P. americana and P. baldwinii, staminodes developed similarly to filaments in shape, length, and time, suggesting that they are vestigial. In P. herniarioides, differences in staminode shape compared to filaments suggests functional co-option. A vascular strand was not present in any of the examined species, perhaps indicating that staminodes are vestigial prior to co-option. Staminodes likely evolved before Paronychia and were lost at least three times. Our results suggest a dynamic history of staminodial evolution in Paronychia, and, perhaps, that selection on the function of staminodes is different across closely related species.


1 - Georgia Southern University, Department of Biology, 4324 Old Register Road, Statesboro, GA, 30460, USA
2 - Georgia Southern University, Department Of Biology, 4324 Old Register Road, Biological Sciences Building, Statesboro, GA, 30458, United States

Keywords:
Ancestor character estimation
androecium
Evo-Devo
floral evolution
floral development
Phylogenetics
staminodes.

Presentation Type: Oral Paper
Number: 0010
Abstract ID:761
Candidate for Awards:None


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