A worldwide phylogeny of Adiantum (Pteridaceae) reveals remarkable convergent evolution in leaf blade architecture
Abstract
© International Association for Plant Taxonomy (IAPT) 2018, All rights reserved. Adiantum
is among the most distinctive and easily recognized leptosporangiate fern genera.
Despite encompassing an astonishing range of leaf complexity, all species of Adiantum
share a unique character state not observed in other ferns: sporangia borne directly
on the reflexed leaf margin or “false indusium” (pseudoindusium). The over 200 species
of Adiantum span six continents and are nearly all terrestrial. Here, we present one
of the most comprehensive phylogenies for any large (200+ spp.) monophyletic, subcosmopolitan
genus of ferns to date. We build upon previous datasets, providing new data from four
plastid markers (rbcL, atpA, rpoA, chlN) for 146 taxa. All sampled taxa can be unequivocally
assigned to one of nine robustly supported clades. Although some of these unite to
form larger, well-supported lineages, the backbone of our phylogeny has several short
branches and generally weak support, making it difficult to accurately assess deep
relationships. Our maximum likelihood-based ancestral character state reconstructions
of leaf blade architecture reveal remarkable convergent evolution across multiple
clades for nearly all leaf forms. A single unique synapomorphy—leaves once-pinnate,
usually with prolonged rooting tips—defines the philippense clade. Although a rare
occurrence in Adiantum, simple leaves occur in three distinct clades (davidii, philippense,
peruvianum). Most taxa have leaves that are more than once-pinnate, and only a few
of these (in the formosum and pedatum clades) exhibit the distinct pseudopedate form.
Distributional ranges for each of the terminal taxa show that most species (75%) are
restricted to only one of six major biogeographical regions. Forty-eight of our sampled
species (nearly one-third) are endemic to South America.
Type
Journal articleSubject
Science & TechnologyLife Sciences & Biomedicine
Plant Sciences
Evolutionary Biology
biogeography
leaf morphology
maidenhair ferns
Neotropics
phylogeny
vittarioids
VITTARIOID FERNS
HIGH-THROUGHPUT
RBCL SEQUENCES
NUCLEOTIDE
NUCLEAR
CLASSIFICATION
POLYPODIALES
BIOGEOGRAPHY
SYSTEMATICS
MORPHOLOGY
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https://hdl.handle.net/10161/21747Published Version (Please cite this version)
10.12705/673.3Publication Info
Huiet, L; Li, FW; Kao, TT; Prado, J; Smith, AR; Schuettpelz, E; & Pryer, KM (2018). A worldwide phylogeny of Adiantum (Pteridaceae) reveals remarkable convergent evolution
in leaf blade architecture. Taxon, 67(3). pp. 488-502. 10.12705/673.3. Retrieved from https://hdl.handle.net/10161/21747.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Kathleen M. Pryer
Professor of Biology

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