TreeBASE Search-Analyses for study 2233

@ARTICLE{TreeBASE2Ref2170, author = {Alan W. Meerow}, title = {Convergence or reticulation? Mosaic evolution in the canalized American Amaryllidaceae.}, year = {2009}, keywords = {}, doi = {}, url = {}, pmid = {}, journal = {Proceedings of the IVth International Conference on the Comparative Biology of the Monocotyledons.}, volume = {}, number = {}, pages = {}, abstract = {Canalization is defined as the suppression of phenotypic variation, or, in the context of molecular evolution, genetic buffering that has evolved under natural selection in order to stabilize the phenotype. Very little is understood on the processes behind canalization, even in todays genomic era. Canalization seems to be a powerful force in the Amaryllidaceae from which only a few lineages have escaped, and this has often in the past led to misdiagnosis of phylogenetic relationships. The American Amaryllidaceae resolves into two well-supported clades with plastid and nrDNA ITS sequences the primarily diploid or dysploid hippeastroid clade (x =11; n = 8, 9, 10, 11, 12), within which there is limited floral morphological diversity, and the Andean tetraploid-derived clade (x = 23), which exhibits greater phenotypic diversity. Moreover, several patterns of morphological diversity in the Andean clade manifest in a homoplastic mosaic at different taxonomic levels in various subclades. Both major clades consist of a small tribe (2-4 genera) that is sister to a larger clade, but only in the hippeastroid group do two genera, Rhodophiala and Zephyranthes, appear polyphyletic based on ITS sequences. Analysis of recombination signal in the ITS alignment supports an hypothesis of reticulation between clades of the hippeastroids, but none in the Andean group. The genus Pyrolirion, historically allied with Zephyranthes on the basis of uniflory, spathe fusion, and upright funnelform, actinomorphic flowers is shown to belong to the tribe Eustephieae in the Andean clade. The mosaic patterns of phenotypic diversity are discussed in the context of genome duplication, possible reticulation, and biogeographic factors.} }