Kreier, Hans-Peter , Schneider, Harald , Smith, Alan R. .
Reconstructing the diversification of the Neotropical epiphytic fern genus Serpocaulon (Polypodiaceae).
RECENT studies on the phylogeny of Polypodiaceae have improved our understanding of the evolution of this diverse lineage of mainly epiphytic ferns. Polypodium was found to be polyphyletic, as usually construed, and a new genus Serpocaulon has been erected for a lineage of exclusively Neotropical species. Serpocaulon has been recognized previously as a putative natural group. The genus is morphologically separated from other Neotropical Polypodiaceae by the combination of usually long-creeping, sparingly branched rhizomes with clathrate, usually peltately attached scales, goniophlebioid venation, and non-paraphysate sori arranged in one to 10 rows between costae and pinna margins. This lineage has highest species diversity within the Andean region but some species are widely distributed in lowland rainforests of Central America and South America. In this study, we infer the diversification of this genus using evidence from four chloroplast markers (rbcL, rps4, rps4-trnS IGS, trnL-F IGS) and one nuclear marker (intron 15 of pgiC). 31 species are currently sampled, with one to four collections per species. This sampling represents about 80% of the species diversity. The most widespread species, S. triseriale, is sister to the remainder of the genus. Within Serpocaulon, we found evidence for a clade comprising those species with the thinnest rhizomes and fewest scales. These species occur predominantly in middle- to high-Andean habitats, whereas the remaining species are found mainly at low to middle elevations. Using our robustly supported phylogenetic framework, we explore evidence for the hypothesis that the diversification of this genus is correlated with the rise of the Andes.
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1 - Albrecht-von-Haller Institute of Plant Sciences, Georg-August Universi, Systematic Botany, Untere Karspüle 2, Göttingen, 37073, Germany
2 - University of Goettingen, Department of Systematic Botany, Albrecht von Haller Institute for Plant Sciences, Untere Karspuele 2, Goettingen, D-37073, Germany
3 - University of California, University Herbarium, Valley Life Science Bldg. 2465, Berkeley, California, 94720, USA
Neotropical plant diversity
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 10:45 AM