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Systematics, biogeography, and character evolution of the legume tribe Fabeae with special focus on the middle-Atlantic island lineages
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Advisor(s)
Abstract(s)
Background: Tribe Fabeae comprises about 380 legume species, including some of the most ancient and
important crops like lentil, pea, and broad bean. Breeding efforts in legume crops rely on a detailed knowledge of
closest wild relatives and geographic origin. Relationships within the tribe, however, are incompletely known and
previous molecular results conflicted with the traditional morphology-based classification. Here we analyse the
systematics, biogeography, and character evolution in the tribe based on plastid and nuclear DNA sequences.
Results: Phylogenetic analyses including c. 70% of the species in the tribe show that the genera Vicia and Lathyrus
in their current circumscription are not monophyletic: Pisum and Vavilovia are nested in Lathyrus, the genus Lens is
nested in Vicia. A small, well-supported clade including Vicia hirsuta, V. sylvatica, and some Mediterranean endemics,
is the sister group to all remaining species in the tribe. Fabeae originated in the East Mediterranean region in the
Miocene (23–16 million years ago (Ma)) and spread at least 39 times into Eurasia, seven times to the Americas,
twice to tropical Africa and four times to Macaronesia. Broad bean (V. faba) and its sister V. paucijuga originated in
Asia and might be sister to V. oroboides. Lentil (Lens culinaris ssp. culinaris) is of Mediterranean origin and together
with eight very close relatives forms a clade that is nested in the core Vicia, where it evolved c. 14 Ma. The Pisum
clade is nested in Lathyrus in a grade with the Mediterranean L. gloeosperma, L. neurolobus, and L. nissolia. The
extinct Azorean endemic V. dennesiana belongs in section Cracca and is nested among Mediterranean species.
According to our ancestral character state reconstruction results, ancestors of Fabeae had a basic chromosome
number of 2n=14, an annual life form, and evenly hairy, dorsiventrally compressed styles.
Conclusions: Fabeae evolved in the Eastern Mediterranean in the middle Miocene and spread from there across
Eurasia, into Tropical Africa, and at least seven times to the Americas. The middle-Atlantic islands were colonized
four times but apparently did not serve as stepping-stones for Atlantic crossings. Long-distance dispersal events are
relatively common in Fabeae (seven per ten million years). Current generic and infrageneric circumscriptions in
Fabeae do not reflect monophyletic groups and should be revised. Suggestions for generic level delimitation are offered.
Description
Keywords
Lathyrus Legumes Lentil Long-distance dispersal Macaronesia Pea Pisum Vicia . Faculdade de Ciências da Vida
Citation
Schaefer, H., Hechenleitner, P., Santos-Guerra, A., Sequeira, M. M., Pennington, R. T., Kenicer, G., & Carine, M. A. (2012). Systematics, biogeography, and character evolution of the legume tribe Fabeae with special focus on the middle-Atlantic island lineages. BMC Evolutionary Biology, 12(1), 1-19. https://doi.org/10.1186/1471-2148-12-250
Publisher
BMC