Molecular systematics and incongruent gene trees of Urophylleae (Rubiaceae)

• The phylogeny of the Pantropical tribe Urophylleae is poorly understood. Earlier phylogenetic work has identified major evolutionary lineages within the group, each geographically restricted to a single continent, but relationships among taxa within these lineages are so far largely unresolved. This study uses parsimony and Bayesian phylogenetic analyses of chloroplast DNA (cpDNA) and nuclear ribosomal DNA (nrDNA) to resolve phylogenetic relationships within Urophylleae. The results show that there are conflicts between cpDNA and nrDNA regarding species-level relationships within Pauridiantha, Urophyllum, and Amphidasya, which provides evidence of a complex genetic history. Different types of tests are used to explore the magnitude of the incongruence and locate the exact nodes in the two gene trees that are in conflict. This approach makes it possible to use the topology from the combined analysis, despite the separate datasets being strongly incongruent, since areas of the tree that are free from conflict can be identified. Based on the results presented in this study, Urophylleae is indicated to consist of Temnopteryx, Raritebe, Amphidasya, Urophyllum s.l., Pauridiantha s.l., and Pentaloncha. Several genera are shown to be nested inside Pauridiantha, two of which have already been included in Pauridiantha based on other data (Pamplethantha, Commitheca), and two which are included in this genus here (Poecilocalyx, Stelechantha). Likewise, three genera are shown to be ingroups in Urophyllum (Pravinaria, Maschalocorymbus, Pleiocarpidia), and are therefore subsumed under this genus. New combinations under Pauridiantha are proposed for three species in Poecilocalyx and three species in Stelechantha, as well as new combinations under Urophyllum for two species in Pravinaria and 17 species in Pleiocarpidia. For one of the latter species a new name is presented to avoid homonymy.

Ämnesord

NATURVETENSKAP  -- Biologi -- Botanik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Botany (hsv//eng)

NATURVETENSKAP  -- Biologi -- Utvecklingsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Developmental Biology (hsv//eng)

Nyckelord

DNA sequence data

incongruence

phylogeny

Rubiaceae

taxonomy

Urophylleae

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