A Diploids-First Approach to Species Delimitation and Interpreting Polyploid Evolution in the Fern Genus Astrolepis (Pteridaceae)

作者：Beck James B^*; Windham Michael D; Yatskievych George; Pryer Kathleen M

来源：Systematic Botany, 2010, 35(2): 223-234.

• Astrolepis
• &quot
• diploids-first&quot
• gapCp
• missing diploid
• polyploidy
• traG-traR

Polyploidy presents a challenge to those wishing to delimit the species within a group and reconstruct the phylogenetic relationships among these taxa. A clear understanding of the tree-like relationships among the diploid species can provide a framework upon which to reconstruct the reticulate events that gave rise to the polyploid lineages. In this study we apply this "diploids-first" strategy to the fern genus Astrolepis (Pteridaceae). Diploids are identified using the number of spores per sporangium and spore size. Analyses of plastid and low-copy nuclear sequence data provide well-supported estimates of phylogenetic relationships, including strong evidence for two morphologically distinctive diploid lineages not recognized in recent treatments. One of these corresponds to the type of Notholaena deltoidea, a species that has not been recognized in any modern treatment of Astrolepis. This species is resurrected here as the new combination Astrolepis deltoidea. The second novel lineage is that of a diploid initially hypothesized to exist by molecular and morphological characteristics of several established Astrolepis allopolyploids. This previously missing diploid species is described here as Astrolepis obscura.

• 出版日期2010-6