Systematics and biogeography ofLathyrus(Leguminosae) based on internal transcribed spacer and cpDNA sequence data

Abstract

Lathyrus(Leguminosae; Papilionoideae) is the largest genus in tribe Fabeae and exhibits an intriguing extratropical distribution. We studied the systematics and biogeography ofLathyrususing sequence data, from accessions representing 53 species, for the internal transcribed spacer plus 5.8S‐coding region of nuclear ribosomal DNA as well as thetrnL‐FandtrnS‐Gregions of chloroplast DNA. Our results generally supported recent morphology‐based classifications, resolving clades corresponding to sectionsLathyrusandLathyrostylis, but question the monophyly of the large, widespread sectionOrobussensu Asmussen and Liston. SectionsOrobus,Aphaca, andPratensisform a predominantly northern Eurasian–New World clade. Within this clade, the North American and eastern Eurasian species, including both Holarctic species (L. palustrisandL. japonicus), form a transberingian clade of relatively recent origin and diversification. The South AmericanNotolathyrusgroup is distant from this transberingian lineage and should be reinstated as a distinct section within the northern Eurasian–New World clade. TheNotolathyruslineage reached the New World most probably through long‐distance dispersal from Eurasia. The remaining sections in the genus are centered on the Mediterranean region.