Abstract Detail


Sundue, Michael [1], Triana Moreno, Luz Amparo [2], Yañez, Agustina [3], Kuo, Li-Yaung [4], Rothfels, Carl [5], Pena, Nelson Túlio L. [6], Schwartsburd, Pedro [7].

Characters that diagnose large clades: Phylogenetic revision of Dennstaedtioideae (Dennstaedtiaceae: Polypodiales).

We undertook a molecular phylogenetic revision of hayscented ferns (Dennstaedtioideae: Dennstaedtiaceae) using four plastid markers. Whereas most ferns are characterized as shade-tolerant understory herbs or epiphytes, hayscented ferns stand out as often being sun-loving and disturbance colonizers. Our sampling represents ca. 40% of the extant diversity and includes the type species for each of the relevant segregate genera. We coded 20 discrete morphological character states which we use to find diagnosable clades. Our reconstructions found that the presence of abaxial and adaxial indusia, sorus position, and rhizome indument, were useful characters at the family level; that is, they exhibited low homoplasy and were generally consistent within large clades. As for characters that help diagnose genera, we found that the presence/absence of epipetiolar buds, the shape of the petiole base, the presence/absence of wings along the rachis-costa junction and perispore ornamentation were most useful. In contrast, the presence/absence of proliferous buds upon the lamina, rhizome branching, aculeae upon axes, lamina division, and had sufficient homoplasy or missing data such that they have less diagnostic power at this rank. In contrast, our results demonstrate that sorus position — the most heavily relied upon character in the classification of Dennstaedtioideae — is homoplastic, changing from abaxial to marginal, sometimes within traditional genera. We show that sorus position changes from marginal to abaxial in the ancestor of the Microlepia clade, and then back to marginal in both Dennstaedtia smithii and D. flaccida. This plasticity was anticipated by Bower while working on Hypolepis, who then concluded that sorus position should not be rigidly used when defining genera as was commonly done by 18th and 19th century botanists. Our results corroborate that sorus position is labile within the Dennstaedtioideae and does not follow a pattern that corresponds to a useful circumscription of genera. Taken together, our results demonstrate that clades of Dennstaedtioideae are morphologically diagnosable, particularly using rhizome, petiole, and perispore characters, and that previous classifications overemphasized sorus position, leading to polyphyletic genera.

1 - The Pringle Herbarium, 111 Jeffords Hall, 63 Carrigan Dr., Burlington, VT, 05405, United States
2 - Universidad de Caldas, Departamento de Ciencias Biológicas, Manizales, Colombia.
3 - Museo Argentino de Ciencias Naturales "Bernardino Rivadavia”, CONICET, División Plantas Vasculares, Ciudad Autónoma de Buenos Aires, Argentina
4 - National Tsing Hua University, Institute Of Molecular & Cellular Biology, Room 327, 3F, Life Science Building One, No.101, Sec., East, Hsinchu, HSZ, 30013, Taiwan
5 - University Of California Berkeley, Berkeley, 94720.0, United States
6 - Universidade Federal de Viçosa, Departamento de Biologia Vegetal, Brazil
7 - Universidade Federal de Viçosa, Departamento de Biologia Vegetal, Brazil


Presentation Type: Oral Paper
Number: PTR1007
Abstract ID:841
Candidate for Awards:Edgar T. Wherry award

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