Abstract Detail



Systematics

Reichelt, Niklas [1], Wen, Jun [2], Paetzold, Claudia [3], Groppo, Milton [4], Appelhans, Marc [5].

A molecular phylogenetic study of Zanthoxylum (Rutaceae) reveals polyphyletic sections and complex worldwide dispersal patterns.

Zanthoxylum is the second largest genus of the Citrus family (Rutaceae). It is the only member with a pantropical distribution, with several temperate species in eastern North America and Asia. Morphologically characteristic are alternate and mostly pinnate leaves, thorny knobs with spines on the stems and branches, and sometimes on the leaf rhachis.   While the biochemical properties of Zanthoxylum have been studied thoroughly, a broad phylogenetic study is missing so far. Here, we present the first molecular phylogenetic study of Zanthoxylum with a worldwide taxon sampling, including species from all members of the ‘proto-Rutaceae’ group. In addition to Zanthoxylum, this monophyletic group consists of the Asian Phellodendron and Tetradium, and the African and Malagasy Fagaraposis. The monotypic genus Toddalia, widespread in Africa and Asia, is embedded within an African and Malagasy clade of Zanthoxylum. Zanthoxylum used to be split into two genera: Zanthoxylum sensu stricto, with temperate species that have homochlamydeous flowers, and the (sub) tropical genus Fagara, with heterochlamydeous flowers. Zanthoxylum s.str., with temperate American and Asian species, is nested within American Fagara. Fagara itself has been subdivided into four sections. Of these, the Caribbean section Tobinia and the monotypic section Mayu from the Juan-Fernández Islands (Chile) are monophyletic. The most species rich and worldwide distributed section Macqueria is largely polyphyletic. Section Blackburnia comprises species from Australia and Pacific Islands. It is resolved as monophyletic in the plastid dataset, but consists of two clades in the nuclear dataset.   A rich fossil record is evident for Zanthoxylum and its closely related genera, so that it is well suited for molecular dating analyses. Molecular dating suggests an Eurasian origin of Zanthoxylum in the Early Eocene. From there, in the Early to Middle Eocene, several migrations took place to East Asia, Africa, and the Americas. A migration from Eurasia to the Americas would have been possible via the North Atlantic Land Bridge and the Bering Land Bridge as temperatures in the Eocene were suitable for subtropical species. This American lineage spread across North and South America and migrated back to Asia likely via the Bering Land Bridge in the Oligocene or Miocene.


1 - University of Goettingen, Albrecht-von-Haller Institute, Unter Karspuele 2, Goettingen, 37073, Germany
2 - Botany, MRC-166 National Museum Of Natural History, 10th St. & Constitution Ave., NW, Mrc 166, Washington/DC, 20013, United States
3 - Albrecht-Haller-Institute for Plant Sciences, Systematics, Biodiversity and Evolution of Plants, Untere Karspüle 2, Goettingen, Lower Saxony, 37073, Germany
4 - Universidade de São Paulo, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Ribeirão Preto, São Paulo, Brazil
5 - University Of Goettingen, Untere Karspuele 2, Goettingen, 37073.0, Germany

Keywords:
Bering Land Bridge
Fagara
eastern Asia-eastern North American disjunction
North Atlantic Land Bridge
Toddalia.

Presentation Type: Poster
Number:
Abstract ID:987
Candidate for Awards:None


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