BACKGROUND
legumes  are grown on 12-15% of the world’s arable surface and account for c. 27% of the world’s primary crop production  <cit> .
the tribe fabeae rchb.
dc., nom.
illeg.)
in particular, a group of five genera and c.  <dig> species  contains several important crop species.
these include the pea , lentil , broad bean , and bitter vetch  that, together with wheat, barley and flax are considered the founder crops of neolithic agriculture in the fertile crescent of western asia  <cit> .
in addition to crops of worldwide importance, the tribe also contains minor crop species , forage or green manure species  and popular ornamentals .
fabeae have an almost worldwide distribution: of the five genera in the tribe, vicia l.  and lathyrus l.  are both most diverse in the eastern mediterranean but extend throughout europe, and both have species in asia, northern to tropical africa, and north and south america  <cit> .
vicia has also colonized hawaii in the pacific  <cit>  and the middle-atlantic archipelagos of the canaries, madeira and azores.
the remaining three genera are small and more localized: lens medik., with 4– <dig> species, and pisum l. with perhaps two species and several subspecies are both most diverse in the eastern mediterranean region; the genus vavilovia al.fed.
with one or two species is native to the west asian mountains  <cit> .
fabeae are absent from most of the lowland tropics and have been introduced to australia and polynesia only very recently with european settlers.
while our knowledge of the systematics and biogeography of the fabaceae is increasing steadily, there are still remarkable gaps.
for the tribe fabeae, the last detailed and comprehensive morphology-based systematic revision was produced by alefeld  <cit> , who divided the group in two tribes ‘viciidae’ and ‘orobidae’ with, collectively,  <dig> genera.
the currently used infrageneric classifications in vicia and lathyrus largely follow the systems suggested by kupicha  <cit> .
for lathyrus, kupicha accepted  <dig> sections  <cit> , which have subsequently been modified by asmussen & liston  <cit>  and more recently by kenicer et al.
<cit> , who accepted eleven sections.
in vicia, kupicha  <cit>  introduced two subgenera, vicia and vicilla, and  <dig> sections with an additional four sections later introduced by maxted  <cit> .
one species was placed in a separate genus anatropostylia <cit>  but has also been treated as a monotypic section anatropostylia of vicia <cit> .
recent molecular phylogenetic studies have focussed on sections or genera.
thus, studies on vicia included up to  <dig> species  <cit> ; phylogenetic studies on the genus lathyrus included up to  <dig> species  <cit> ; several studies analysed the genera lens <cit>  and pisum <cit> ; finally, oskoueiyan et al.
<cit>  analysed the phylogenetic position of vavilovia.
full chloroplast genomes have recently become available for lathyrus sativus and pisum sativum <cit> .
in contrast to this growing body of analyses at the generic and sectional level, there are few studies dealing with the entire tribe.
the only exceptions are family-wide or multi-tribe legume phylogenetic studies, which included a limited sample of species across fabeae .
those studies suggested that fabeae is monophyletic and sister group to the clover genus trifolium l. even though sampling of fabeae in those family-wide studies has been limited, they suggest that plastid dna sequence data do not agree with morphology-based genus circumscriptions in the tribe and that vicia might be paraphyletic  <cit> .
altogether, these studies highlight the need of a comprehensive tribal-level study of fabeae.
several hypotheses have been proposed to explain the worldwide distribution of fabeae but there has been no comprehensive biogeographic analysis of the entire tribe.
simola  <cit>  suggested a south american origin of lathyrus followed by a dispersal event to africa and then into the mediterranean.
in contrast, kupicha  <cit>  suggested that lathyrus and vicia originated at high latitudes in the old world, and might have migrated later to the mediterranean and to north america via greenland or from asia via beringia to alaska.
from north america, the lineages could have spread into south america in the late tertiary.
a north american origin of the south american notolathyrus group was also suggested by burkart  <cit>  and asmussen & liston  <cit> .
based on dna sequence data, kenicer et al.
<cit>  suggested an eastern mediterranean origin for lathyrus followed by range expansion into northern eurasia.
the beringian land bridge would then have allowed migration into north america.
according to kenicer et al.
<cit> , the most likely origin of the south american lathyrus species is directly from eurasia via long-distance dispersal .
in this context the question arises whether those lineages used stepping-stone islands in the middle-atlantic as suggested by axelrod  <cit>  and more recently by fernández-palacios et al.
<cit> .
the stepping-stone hypothesis is supported by the existence of forty-five species of fabeae on the volcanic oceanic atlantic islands of which nine are currently considered as endemic to one or more of the islands.
on iceland in the extreme north, five species are possibly native  and four occur as casuals  gray, v. sativa, v. villosa)  <cit> .
further to the south, in the azores archipelago, a total of  <dig> vicia,  <dig> lathyrus, and lens culinaris have been reported  <cit> .
all are considered introduced  <cit> , with the exception of vicia dennesiana h. c. watson , which is endemic to the azorean island of são miguel but has not been seen since the mid 19th century  <cit> .
for madeira,  <dig> vicia,  <dig> lathyrus, and lens culinaris have been reported  <cit> .
of those, three species are endemic to madeira ,  <dig> others considered native, and nine are probably introduced  <cit> .
in the canary islands,  <dig> vicia,  <dig> lathyrus, two lens, and one pisum species have been found  <cit> .
five species are currently considered to be endemic to the canaries: vicia chaetocalyx webb & berthel., v. cirrhosa c. sm.
ex webb & berthel.
, v. filicaulis webb & berthel., v. nataliae u. reifenb.
& a.reifenb., and v. scandens r.p.murray.
of the remainder  <dig> are considered at least possibly native, and  <dig> are very likely recent introductions  <cit> .
no native fabeae have been reported from the selvagens or, further south, from cape verdes, st. helena, or tristan da cunha.
the aims of this study were to examine the evolution, biogeography and classification of fabeae.
newly generated plastid and nuclear dna sequence data  region) for fabeae species from the middle-atlantic islands, north and south america, africa, and eurasia are analysed in conjunction with previously published data to establish a phylogeny of the tribe that includes c. 70% of the accepted species , with representatives sampled from all sections and all geographic regions in which the tribe occurs.
this phylogenetic framework is used to  test current morphology-based generic and infrageneric circumscriptions and  analyse the evolution of characters used for generic and infrageneric delimitation, notably stylar and life form characters  <cit> .
using a bayesian relaxed molecular clock approach and ancestral range reconstruction, we further test the hypothesis of a eurasian origin followed by dispersal to the americas  across the atlantic or  via land bridges or ‘stepping stone’ islands.
RESULTS
phylogenetic analyses
maximum likelihood  and bayesian analyses of chloroplast  and nuclear ribosomal its sequence data for  <dig> of the c.  <dig> species currently accepted in the tribe  yield a generally well-resolved and statistically supported phylogeny although some nodes of interest are only weakly or not supported .
the nuclear ribosomal its  and combined plastid  phylogenies are congruent .
we thus find no evidence for a strong effect of hybridization in the evolution of the fabeae and analyses of a combined matrix is justified.
our results confirm the monophyly of lens and pisum  and the paraphyly of vicia.
in contrast to previous studies, we find that lathyrus is not monophyletic and includes pisum and vavilovia .
currently recognized subgenera in vicia and sections with more than one species in both vicia and lathyrus are mostly not recovered as monophyletic groups .
of the  <dig> sections in lathyrus, sections neurolobus, nissolia, orobon, orobastrum, and viciopsis are monotypic.
our sampling strategy allowed us to test the monophyly of seven of the eight sections of lathyrus that comprise multiple species.
only notolathyrus and pratensis are found to be monophyletic .
we had material of only one of the two species in section aphaca but since the two species are distinguishable only through slight differences in style shape and fruit morphology, section aphaca is very likely also monophyletic.
sections orobon and orobastrum are both nested in section lathyrus.
section linearicarpus is polyphyletic: l. hygrophilus taub.
and l. inconspicuus l. group together , whereas l. angulatus l.  belongs to section lathyrus  and l. sphaericus groups with section lathyrostylis .
lathyrus gloeosperma warb.
& eig from kupicha’s section clymenum groups with l. nissolia l. in the ml reconstruction .
lathyrus saxatilis  vis.
is placed in the core vicia and may be sister to a clade that includes v. dumetorum l. and v. americana muhl.
ex willd.
although its closest relatives in vicia are unclear due to low support values .
list of the sections based on kupicha’s system  <cit>  and maxted’s modifications in vicia <cit>  with total species number, number of species included in our analyses and status as monophyletic or not based on the molecular results.
within vicia s.str., most of the species of kupicha’s subgenus vicia group together, with the notable exception of vicia narbonensis l. and close relatives  from the eastern mediterranean and asia minor.
the second subgenus, vicilla, is clearly polyphyletic .
nine of the  <dig> sections currently recognized in vicia are monotypic: sections anatropostylia, bithynicae, ervoides, lentopsis, mediocinctae, microcarinae, perditae, subvillosae, and volutae .
our sampling strategy allowed us to test the monophyly of  <dig> of the  <dig> remaining sections.
of these, sections americanae, ervum, faba, narbonensis, peregrinae, and trigonellopsis are found to be monophyletic.
section cracca is not monophyletic because  sections lentopsis, panduratae, perditae, variegatae, and volutae are nested in a clade otherwise comprising species from this section and  vicia chaetocalyx and v. hirsuta that were previously assigned to this section are placed outside the cracca clade .
with regards to section vicilla, v. americana, v. bungei ohwi, v. crocea  b.
fedtsch., v. dumetorum, v. gigantea, and v. nigricans are not resolved with other members of the section.
these species are resolved as paraphyletic with respect to sections cassubicae and amurense.
section australes is shown to be paraphyletic with respect to section mediocinctae and section pedunculatae includes section americanae and v. dumetorum .
section vicia is also not monophyletic because sections atossa, hypechusa, peregrinae, and faba are nested within it.
vicia section ervum is sister to all lathyrus species  plus pisum and vavilovia .
vicia sections ervilia, ervoides, and trigonellopsis group together  and form a clade that is sister to all other fabeae .
at the species level, our material of the macaronesian endemic vicia chaetocalyx is nested in a highly supported clade of v. lutea l. accessions .
there is no resolution in the v. cirrhosa group from the canaries and madeira in any of the analyses .
in contrast, the v. sativa group is genetically quite heterogeneous, especially in nuclear its sequences  and while v. sativa s.l.
is monophyletic, the different accessions of v. angustifolia and v. sativa s.str.
do not group together.
in the v. tetrasperma lineage, v. tenuissima schinz & thell.
and v. pubescens  link are genetically distinct from v. tetrasperma  schreb.
s. str.
both in its  and combined plastid sequences .
nuclear its sequence differences also support the separation of north and south american populations of v. nigricans s. l. as v. gigantea hook.
and v. nigricans hook.
& arn.
s. str.
respectively .
heterogeneity at the genetic level is also evident for the lathyrus aphaca l. clade, a morphologically variable taxon widespread from the macaronesian islands to the himalayas .
in contrast, lathyrus undulatus boiss.
and l. miniatus steven do not appear to be genetically distinct from l. rotundifolius willd.
s. str.
and the romanian endemic l. hallersteinii baumg.
is nested in a highly supported clade of l. pratensis accessions .
molecular dating and ancestral range reconstruction
the results of our bayesian molecular clock and ancestral range analyses suggest a mediterranean origin and a crown age of c. 23– <dig> myr for fabeae, with a best estimate for the associated substitution rate of  <dig>  substitutions per site per myr  .
we reconstruct a minimum of three dispersal events to the middle-atlantic islands  and seven to the americas.
none of the new world lineages originates from the atlantic islands .
the oldest macaronesian lineage, the vicia scandens clade, split from a mediterranean ancestor  <dig> - <dig>  ma,  <dig>  subst/site/my  and colonized the canary islands and madeira plus porto santo .
the second dispersal led to the establishment of the vicia dennesiana lineage in the azores.
the age estimate for this event is not very robust due to the low resolution in the v. cracca clade, where v. dennesiana is placed but it occurred probably more recently than the canary island lineage, between  <dig> - <dig>  ma,  <dig>  subst/site/my .
the remaining colonization events are even more recent: the madeiran species or form vicia pectinata lowe split from the mediterranean vicia sativa  <dig> - <dig>  ma , whereas the canary island vicia chaetocalyx is nested in a clade of the mainly mediterranean vicia lutea  and might have arrived only with the first human settlers.
we reconstruct seven migration events to the new world:  the vicia nigricans clade split from the eurasian vicia lineages  <dig> - <dig>  ma .
this split is reconstructed as a long distance dispersal  event from the mediterranean region to south america with high support  but the vicia nigricans clade might also be sister to the caucasian v. crocea , which would indicate dispersal from asia via beringia.
the ancestor of the hawaiian endemic vicia menziesii spreng.
then dispersed from western america to hawaii  <dig> - <dig>  ma,  <dig>  subst/site/my ;  the north american vicia ludoviciana nutt.
clade split from a mediterranean ancestral lineage  <dig> - <dig>  ma and dispersed across the atlantic, possibly floating in surface water ;  the mainly south american vicia section australes  split from a mediterranean ancestral lineage  <dig> - <dig>  ma  and is again most likely a case of ldd across the atlantic ;  the south american section notolathyrus split from a mediterranean ancestral lineage  <dig> - <dig>  ma , representing the third ldd event in the same time window of 9– <dig> ma ;  the large clade of north american species in lathyrus section orobus split from an asian ancestral lineage  <dig> - <dig>  ma,  <dig>  subst/site/my ;  colonization of the north american coasts by the lathyrus littoralis/l.
japonicus lineage started c. 3– <dig>  ma,  <dig>  subst/site/my ;  and finally the split between the north american vicia americana and its asian sister v. bungei is dated to  <dig> - <dig>  ma,  <dig>  subst/site/my .
origin of the crop species in fabeae
the pea, pisum sativum s. l.  is sister to the eastern mediterranean pisum fulvum sibth.
& sm.
and both are sister to vavilovia formosa  fed.
alef.)
and v. aucheri  fed.
from the caucasus mountains .
the crown age of the pisum clade is estimated to  <dig> - <dig>  ma ; the divergence between pisum and vavilovia dates back to  <dig> - <dig>  ma .
lentil, lens culinaris ssp.
culinaris, is nested among a group of very closely related taxa.
their mostly allopatric distribution, morphological similarity and very recent divergence estimates suggest that they might be best treated as subspecies or varieties of lens culinaris.
all together are sister to the mediterranean lens nigricans  godr.
.
the split between the l. culinaris group and l. nigricans occurred  <dig> - <dig>  ma, whereas the stem lineage of lens might have split from its vicia ancestors  <dig> - <dig>  ma.
faba bean or broad bean, vicia faba is sister to the himalayan v. paucijuga b.
fedtsch., which is often treated as a subspecies of v. faba.
both are nested in section vicia  with an estimated stem age of 8– <dig>  ma but this is not robust due to the lack of a well supported placement of the lineage in any of our phylogeny estimates .
the ancient crop species vicia ervilia is placed in the ervilia clade that is here recovered as the sister group to all other fabeae.
it split from its closest relatives in the v. sylvatica l. clade  <dig> - <dig>  ma .
vicia sativa belongs in a group of closely related and insufficiently studied mediterranean taxa.
in our ml and bayesian analyses, the v. sativa group  is consistently reconstructed as sister to v. pyrenaica pourr.
from which it split  <dig> - <dig>  ma.
the economically most important species in the genus lathyrus, the ornamental sweet pea, l. odoratus, from southern italy and sicily, is sister to the wider mediterranean l. hirsutus l. , from which it diverged  <dig> - <dig>  ma .
finally, the minor crop l. sphaericus is sister to the mediterranean l. bauhinii genty clade , from which it diverged  <dig> - <dig>  ma .
character evolution
annual life form is reconstructed as ancestral in the tribe and a perennial life form evolved at least  <dig> times independently followed by several reversals to annual life form .
the ml ancestral character reconstruction indicates that a basic chromosome number of 2n= <dig> is most likely for the origin of the tribe .
from that, reductions to 2n= <dig> or 2= <dig> and duplications to 2n= <dig>  2n= <dig>  and 2= <dig> have occurred.
major clades in fabeae seem to be characterized by common stylar pubescence patterns .
from an originally evenly hairy style , the lathyrus-pisum-vavilovia clade evolved an adaxially hairy style, whereas some of the more derived vicia clades are dominated by an abaxially hairy style.
there are, however, many exceptions: lathyrus saxatilis, for example, with an adaxially hairy style is deeply nested in vicia.
the asian vicia subvillosa  boiss.
has a unique type of style with v-shaped hairy areas.
it is unknown whether this character is shared with its african sister species v. malosana  baker f., v. paucifolia baker, and v. claessensii de wild.
another unique pattern is found in v. leucophaea, which has a densely hairy ring on its style that seems to have evolved from an abaxially hairy style .
style shape, another traditional character for fabeae classification, varies little within the tribe: most species have a dorsiventrally compressed style, which is also reconstructed as most likely ancestral condition in the tribe .
exceptions are most of the vicia species in section cracca, which have a laterally compressed style.
a terete style  has evolved six to seven times independently in the tribe: in the mediterranean v. pubescens, the eurasian v. hirsuta and vicia crocea, the north american v. leucophaea, and the east asian v. amurensis oett., v. tibetica prain ex c.e.e.
fisch., v. nummularia hand.-mazz., and v. dichroantha diels.
furthermore, pisum and vavilovia are characterised by a longitudinally folded style otherwise unknown in the tribe.
discussion
taxonomic implications
the molecular data show that most of the currently recognized genera and subgenera, as well as many of the traditional sections are not monophyletic.
pisum and vavilovia are sister groups and nested in lathyrus, which together with lens is nested in vicia.
this grouping is also supported from the  currently available whole plastid genomes for fabeae: lathyrus sativus and pisum sativum share four gene losses  and the loss of the first intron of clpp and the cis-intron of rps <dig>  <cit> .
pisum and lathyrus furthermore share the phytoalexin pisatin, which was not found in vicia and lens <cit> .
the two latter genera both had the phytoalexin wyerone in all analysed species except in vicia articulata and v. ervilia <cit> , which we find to be sister to all vicieae.
thus the presence of wyerone could be a synapomorphy for vicia and lens.
apart from alefeld’s concept of splitting the tribe into a multitude of tiny genera  <cit> , the most radical solution to obtain a more natural classification of fabeae would be the transfer of all species of the four currently accepted smaller genera to a broadly circumscribed genus vicia.
this, however, would require more than  <dig> new combinations.
an alternative  solution would be to transfer pisum and vavilovia to a then monophyletic lathyrus.
vicia section ervum , and v. pubescens) could be raised to genus-level; the name ervum l. with the lectotype e. tetraspermum l. is available.
a monophyletic vicia could then be obtained by transferring lens and lathyrus saxatilis to vicia.
the clade comprising vicia cypria kotschy, v. lunata  boiss., v. ervilia, v. hirsuta , v. sylvatica , v. monanthos  desf.
and v. articulata hornem.
kupicha) and v. quadrijuga p.h.davis very likely belong here too, so that a genus ervilia would probably comprise at least nine species.
most of the sections also need to be revised if they are supposed to reflect monophyletic groupings: section cracca should include the former sections lentopsis, panduratae, perditae, variegatae, and volutae.
section vicilla should be recircumscribed to include sections amurense and cassubicae.
section mediocinctae could be lumped with section australes.
section pedunculatae should be merged with section americanae.
section vicia could be defined in a broader sense to accommodate sections atossa, bithynicae, faba , hypechusa, microcarinae, peregrinae, and wiggersia.
in lathyrus, the clade including l. alpestris  kit.
ex reichb.
and l. vernus  bernh.
could be split from section orobus.
sections orobon and orobastrum could be lumped with section lathyrus.
the circumscriptions of sections linearicarpus, lathyrus, and lathyrostylis all need to be slightly modified in order to obtain monophyletic groups.
newly discovered fabeae clades that might warrant description of additional sections include  the sister group of section subvillosae, comprising the african v. claessensii, v. malosana, and v. paucifolia ;  the pacific coast clade including v. nigricans, v. gigantea, and v. menziesii;  vicia crocea, which might best be placed in a monotypic section even though additional work might reveal a sister group relationship to the v. nigricans clade.
the results of our phylogenetic analyses show that lathyrus saxatilis is currently included in the wrong genus: the two accessions we have are both placed in the core vicia in our phylogeny and even though our data are not sufficient to pinpoint its exact position  it should certainly be treated as vicia saxatilis  tropea.
the taxon was described as orobus saxatilis by ventenat but interestingly, it was already transferred to vicia in the early 20th century .
kupicha discusses the morphological affinity to vicia  but although expressing some doubts, the dorsally compressed and adaxially pubescent style led her to include it in lathyrus in a new monospecific section viciopsis  <cit> .
regarding the azorean endemic v. dennesiana , we reject kupicha’s concept of a monotypic section perditae and find that the species belongs in the mediterranean clade of section cracca, where it also fits well based on stylar morphology  <cit> .
the available herbarium specimens for this presumably extinct taxon show a striking overall morphological similarity to the v. nigricans group of the american pacific coasts and hawaii  <cit>  but our partial dna sequence data  reject a close relationship.
kupicha  <cit>  suggested that this species might be a biogeographic link explaining some of the amphi-atlantic distribution patterns in vicia but our analyses strongly suggest a single ldd event out of the mediterranean to the azores.
our phylogeny estimates cast some doubt on species concepts applied in the canary islands and madeira: the canarian endemic vicia chaetocalyx is nested in macaronesian and mediterranean v. lutea accessions and it seems clear that the sequenced material should be assigned to the latter species because they are morphologically almost identical.
however, our material came from a recently described population in gran canaria  <cit>  and not from the original type material collected by webb and berthelot and now in the florence herbarium, which should be used for further genetic study.
a similar problem was reported in a recent study on an endemic bird species from the cape verde archipelago  <cit> .
the four canary and madeira endemics in the v. cirrhosa group show no genetic differences in any of the sequenced regions.
since morphological differences are also minor, a re-evaluation of the group might be necessary .
in contrast, we find a high genetic variability among the relatively few samples included from the v. sativa group, where additional macaronesian endemics might have been overlooked.
lowe’s vicia pectinata for example, has been synonymized with the widespread v. sativa but we find three substitutions in the its region, which seem to be unique to lowe’s taxon.
together with some morphological differences and the obvious isolation of the population on an oceanic island, there might be enough evidence to reinstate v. pectinata.
however, a more detailed study of the vicia sativa group in macaronesian with several samples per island would be required to properly address this question.
biogeographic history of the tribe
the origin of fabeae is estimated to lie in the middle miocene .
this result, however, could be expected since we constrained the vicia s.l.
crown to  <dig>  ma under a normal prior distribution with standard deviation of  <dig>  million years.
ldd events  are relatively common in fabeae.
we reconstruct  <dig> ldd events over the period of c.  <dig> million years, which translates into a rate of c.  <dig> successful ldd events per  <dig> million years.
the same rate was found for cucurbitaceae  <cit>  but sampling density in that study was lower , so the cucurbit rate is very likely an underestimate.
migration via greenland and the north atlantic land bridge is not an option in fabeae since the entire tribe is too young .
migration across the beringian land bridge is likely for at least one lineage: the ancestors of the pacific coast species vicia nigricans, v. gigantea, and the hawaiian v. menziesii.
however, since the lineage later managed to colonize the isolated hawaiian archipelago, ldd across the pacific from asia to the american pacific coast is also an option or, less parsimonious, ldd from the mediterranean to the american continent followed by spread to the west coast and extinction in the east.
the next three fabeae lineages, vicia section australes, lathyrus section notolathyrus, and the v. ludoviciana clade, all reached the american continent in the same time window  via ldd from the mediterranean region across the atlantic.
this suggests favourable conditions for legume seed dispersal in the late miocene, a ‘window of opportunity’ in the sense of carine  <cit> .
with the opening of the bering strait, c.  <dig> - <dig>  ma  <cit> , it became temporarily impossible to migrate to the americas over land but later reconnections might have allowed terrestrial migration of cold-adapted lineages.
for the ancestors of lathyrus japonicus/l.
littoralis, l. palustris, the large new world clade in lathyrus section orobus, and vicia americana we can thus not decide between terrestrial migration and ldd.
more recently, there might have been some transport across the region by inuit, who use the roasted seeds to prepare drinks  <cit> .
for l. japonicus and l. palustris the most likely direction is a spread from asia to north america.
in contrast, the v. americana lineage might have come the opposite way from north america  to asia .
both v. americana and v. bungei are sister to the european vicia onobrychioides l. and v. dumetorum and the ancestral lineage of the latter species might have spread into north america across the north atlantic.
the now extinct azorean endemic vicia dennesiana might have reached the azorean archipelago in the north atlantic via ldd c.  <dig> ma and the canary islands and madeira endemics of the vicia scandens clade colonized those archipelagos via ldd about  <dig> ma.
we can therefore reject the hypothesis of ancient stepping stone dispersal via the atlantic islands because all the island lineages are relatively recent arrivals compared to the age of macaronesia  and none of the american lineages is nested in an atlantic island clade.
in some cases our age estimates might also be biased old because of extinction events.
the vicia dennesiana and v. scandens lineages could represent the last survivors of previously more species-rich eurosiberian clades in macaronesian refugia and might be even younger than estimated if the northwest african species of section cracca were included, for which we failed to obtain material.
evolution of life form and floral morphology in fabeae
ancestral character reconstruction shows that life form, stylar characters, and chromosome number are of limited value for systematic grouping of fabeae.
style shape, a traditional character for fabeae classification  <cit> , varies little within the tribe: most species have a dorsiventrally compressed style, which is also reconstructed as most likely ancestral condition in the tribe .
the finding that an annual life form is most likely the ancestral state in the tribe is unexpected and rejects earlier hypotheses of multiple evolution of annual life form as an adaptation to range expansion into xeric habitats  <cit> .
it fits, however, with the result of the biogeographic analysis locating the region of origin in the mediterranean and not in the temperate or boreal forests, where a perennial life form would have been an advantage.
a basic chromosome number of 2n= <dig> has already been suggested by other authors , an ancestral, evenly hairy, dorsiventrally compressed style fits with recent results of small-scale character reconstructions  <cit> .
origin of legume crops
our analyses shed light on a group of generally overlooked mediterranean lathyrus species that apart from the caucasian vavilovia species might be very interesting for breeding of new pisum varieties due to benefitial traits including drought tolerance and perennial life form: l. gloeosperma, l. neurolobus boiss.
& heldr., and l. nissolia all have affinities to the pisum plus vavilovia clade and might be included in breeding programs.
the placement of v. faba far from the other members of section faba sensu kupicha  <cit>  and somewhere among v. oroboides wulfen, v. bithynica  l., and the v. sativa-v. sepium clade  is in agreement with earlier morphological, cytological and dna studies  <cit> .
vicia faba differs in chromosome number from most of the suggested relatives found in our analyses.
vicia bithynica, v. oroboides, and v. sepium all have 2n= <dig> chromosomes, whereas v. faba  has 2n= <dig> , which will make crossings for plant breeding purposes difficult.
the lens clade has its closest relatives among early branching vicia clades followed by c.  <dig> million years of independent evolution.
while this could be a big obstacle for breeding efforts, the species of the african v. paucifolia complex and the asian v. subvillosa might be worth testing if initial screenings reveal benefitial traits.
for the v. sativa complex, a sister group relationship to v. pyrenaica seems very likely and the species should be explored.
the high sequence diversity detected among our accessions of v. sativa s.l.
corresponds to earlier findings of karyological and aflp studies  <cit>  and a detailed revision of the group is recommended in order to detect the most useful growth forms.
CONCLUSIONS
based on nuclear and chloroplast phylogenies, we conclude that tribe fabeae evolved in the eastern mediterranean in the middle miocene.
ancestral fabeae probably were annual plants with a chromosome number of 2n= <dig>  and evenly hairy, dorsiventrally compressed style.
from the mediterranean, the tribe expanded its range at least  <dig> times into central and western europe and  <dig> times to asia, twice to tropical africa, and at least seven times across the atlantic/pacific to the americas.
the middle-atlantic islands were colonized four times but did not serve as stepping-stones for lineages colonizing the new world.
our biogeographic analyses show that long distance dispersal events are relatively common in fabeae .
current generic and infrageneric circumscriptions in fabeae do not reflect monophyletic groups and should be revised.

 legumes are grown on 12-15% of the world’s arable surface and account for c. 27% of the world’s primary crop production. the tribe fabeae rchb. dc., nom. illeg.) in particular, a group of five genera and c. species contains several important crop species. these include the pea, lentil, broad bean, and bitter vetch that, together with wheat, barley and flax are considered the founder crops of neolithic agriculture in the fertile crescent of western asia. in addition to crops of worldwide importance, the tribe also contains minor crop species, forage or green manure species and popular ornamentals. fabeae have an almost worldwide distribution: of the five genera in the tribe, vicia l. and lathyrus l. are both most diverse in the eastern mediterranean but extend throughout europe, and both have species in asia, northern to tropical africa, and north and south america. vicia has also colonized hawaii in the pacific and the middle-atlantic archipelagos of the canaries, madeira and azores. the remaining three genera are small and more localized: lens medik., with 4– species, and pisum l. with perhaps two species and several subspecies are both most diverse in the eastern mediterranean region; the genus vavilovia al.fed. with one or two species is native to the west asian mountains. fabeae are absent from most of the lowland tropics and have been introduced to australia and polynesia only very recently with european settlers. while our knowledge of the systematics and biogeography of the fabaceae is increasing steadily, there are still remarkable gaps. for the tribe fabeae, the last detailed and comprehensive morphology-based systematic revision was produced by alefeld, who divided the group in two tribes ‘viciidae’ and ‘orobidae’ with, collectively, genera. the currently used infrageneric classifications in vicia and lathyrus largely follow the systems suggested by kupicha. for lathyrus, kupicha accepted sections, which have subsequently been modified by asmussen & liston and more recently by kenicer et al., who accepted eleven sections. in vicia, kupicha introduced two subgenera, vicia and vicilla, and sections with an additional four sections later introduced by maxted. one species was placed in a separate genus anatropostylia but has also been treated as a monotypic section anatropostylia of vicia. recent molecular phylogenetic studies have focussed on sections or genera. thus, studies on vicia included up to species; phylogenetic studies on the genus lathyrus included up to species; several studies analysed the genera lens and pisum; finally, oskoueiyan et al. analysed the phylogenetic position of vavilovia. full chloroplast genomes have recently become available for lathyrus sativus and pisum sativum. in contrast to this growing body of analyses at the generic and sectional level, there are few studies dealing with the entire tribe. the only exceptions are family-wide or multi-tribe legume phylogenetic studies, which included a limited sample of species across fabeae. those studies suggested that fabeae is monophyletic and sister group to the clover genus trifolium l. even though sampling of fabeae in those family-wide studies has been limited, they suggest that plastid dna sequence data do not agree with morphology-based genus circumscriptions in the tribe and that vicia might be paraphyletic. altogether, these studies highlight the need of a comprehensive tribal-level study of fabeae. several hypotheses have been proposed to explain the worldwide distribution of fabeae but there has been no comprehensive biogeographic analysis of the entire tribe. simola suggested a south american origin of lathyrus followed by a dispersal event to africa and then into the mediterranean. in contrast, kupicha suggested that lathyrus and vicia originated at high latitudes in the old world, and might have migrated later to the mediterranean and to north america via greenland or from asia via beringia to alaska. from north america, the lineages could have spread into south america in the late tertiary. a north american origin of the south american notolathyrus group was also suggested by burkart and asmussen & liston. based on dna sequence data, kenicer et al. suggested an eastern mediterranean origin for lathyrus followed by range expansion into northern eurasia. the beringian land bridge would then have allowed migration into north america. according to kenicer et al., the most likely origin of the south american lathyrus species is directly from eurasia via long-distance dispersal. in this context the question arises whether those lineages used stepping-stone islands in the middle-atlantic as suggested by axelrod and more recently by fernández-palacios et al.. the stepping-stone hypothesis is supported by the existence of forty-five species of fabeae on the volcanic oceanic atlantic islands of which nine are currently considered as endemic to one or more of the islands. on iceland in the extreme north, five species are possibly native and four occur as casuals gray, v. sativa, v. villosa). further to the south, in the azores archipelago, a total of vicia, lathyrus, and lens culinaris have been reported. all are considered introduced, with the exception of vicia dennesiana h. c. watson, which is endemic to the azorean island of são miguel but has not been seen since the mid 19th century. for madeira, vicia, lathyrus, and lens culinaris have been reported. of those, three species are endemic to madeira, others considered native, and nine are probably introduced. in the canary islands, vicia, lathyrus, two lens, and one pisum species have been found. five species are currently considered to be endemic to the canaries: vicia chaetocalyx webb & berthel., v. cirrhosa c. sm. ex webb & berthel., v. filicaulis webb & berthel., v. nataliae u. reifenb. & a.reifenb., and v. scandens r.p.murray. of the remainder are considered at least possibly native, and are very likely recent introductions. no native fabeae have been reported from the selvagens or, further south, from cape verdes, st. helena, or tristan da cunha. the aims of this study were to examine the evolution, biogeography and classification of fabeae. newly generated plastid and nuclear dna sequence data region) for fabeae species from the middle-atlantic islands, north and south america, africa, and eurasia are analysed in conjunction with previously published data to establish a phylogeny of the tribe that includes c. 70% of the accepted species, with representatives sampled from all sections and all geographic regions in which the tribe occurs. this phylogenetic framework is used to test current morphology-based generic and infrageneric circumscriptions and analyse the evolution of characters used for generic and infrageneric delimitation, notably stylar and life form characters. using a bayesian relaxed molecular clock approach and ancestral range reconstruction, we further test the hypothesis of a eurasian origin followed by dispersal to the americas across the atlantic or via land bridges or ‘stepping stone’ islands.  phylogenetic analyses maximum likelihood and bayesian analyses of chloroplast and nuclear ribosomal its sequence data for of the c. species currently accepted in the tribe yield a generally well-resolved and statistically supported phylogeny although some nodes of interest are only weakly or not supported. the nuclear ribosomal its and combined plastid phylogenies are congruent. we thus find no evidence for a strong effect of hybridization in the evolution of the fabeae and analyses of a combined matrix is justified. our results confirm the monophyly of lens and pisum and the paraphyly of vicia. in contrast to previous studies, we find that lathyrus is not monophyletic and includes pisum and vavilovia. currently recognized subgenera in vicia and sections with more than one species in both vicia and lathyrus are mostly not recovered as monophyletic groups. of the sections in lathyrus, sections neurolobus, nissolia, orobon, orobastrum, and viciopsis are monotypic. our sampling strategy allowed us to test the monophyly of seven of the eight sections of lathyrus that comprise multiple species. only notolathyrus and pratensis are found to be monophyletic. we had material of only one of the two species in section aphaca but since the two species are distinguishable only through slight differences in style shape and fruit morphology, section aphaca is very likely also monophyletic. sections orobon and orobastrum are both nested in section lathyrus. section linearicarpus is polyphyletic: l. hygrophilus taub. and l. inconspicuus l. group together, whereas l. angulatus l. belongs to section lathyrus and l. sphaericus groups with section lathyrostylis. lathyrus gloeosperma warb. & eig from kupicha’s section clymenum groups with l. nissolia l. in the ml reconstruction. lathyrus saxatilis vis. is placed in the core vicia and may be sister to a clade that includes v. dumetorum l. and v. americana muhl. ex willd. although its closest relatives in vicia are unclear due to low support values. list of the sections based on kupicha’s system and maxted’s modifications in vicia with total species number, number of species included in our analyses and status as monophyletic or not based on the molecular results. within vicia s.str., most of the species of kupicha’s subgenus vicia group together, with the notable exception of vicia narbonensis l. and close relatives from the eastern mediterranean and asia minor. the second subgenus, vicilla, is clearly polyphyletic. nine of the sections currently recognized in vicia are monotypic: sections anatropostylia, bithynicae, ervoides, lentopsis, mediocinctae, microcarinae, perditae, subvillosae, and volutae. our sampling strategy allowed us to test the monophyly of of the remaining sections. of these, sections americanae, ervum, faba, narbonensis, peregrinae, and trigonellopsis are found to be monophyletic. section cracca is not monophyletic because sections lentopsis, panduratae, perditae, variegatae, and volutae are nested in a clade otherwise comprising species from this section and vicia chaetocalyx and v. hirsuta that were previously assigned to this section are placed outside the cracca clade. with regards to section vicilla, v. americana, v. bungei ohwi, v. crocea b. fedtsch., v. dumetorum, v. gigantea, and v. nigricans are not resolved with other members of the section. these species are resolved as paraphyletic with respect to sections cassubicae and amurense. section australes is shown to be paraphyletic with respect to section mediocinctae and section pedunculatae includes section americanae and v. dumetorum. section vicia is also not monophyletic because sections atossa, hypechusa, peregrinae, and faba are nested within it. vicia section ervum is sister to all lathyrus species plus pisum and vavilovia. vicia sections ervilia, ervoides, and trigonellopsis group together and form a clade that is sister to all other fabeae. at the species level, our material of the macaronesian endemic vicia chaetocalyx is nested in a highly supported clade of v. lutea l. accessions. there is no resolution in the v. cirrhosa group from the canaries and madeira in any of the analyses. in contrast, the v. sativa group is genetically quite heterogeneous, especially in nuclear its sequences and while v. sativa s.l. is monophyletic, the different accessions of v. angustifolia and v. sativa s.str. do not group together. in the v. tetrasperma lineage, v. tenuissima schinz & thell. and v. pubescens link are genetically distinct from v. tetrasperma schreb. s. str. both in its and combined plastid sequences. nuclear its sequence differences also support the separation of north and south american populations of v. nigricans s. l. as v. gigantea hook. and v. nigricans hook. & arn. s. str. respectively. heterogeneity at the genetic level is also evident for the lathyrus aphaca l. clade, a morphologically variable taxon widespread from the macaronesian islands to the himalayas. in contrast, lathyrus undulatus boiss. and l. miniatus steven do not appear to be genetically distinct from l. rotundifolius willd. s. str. and the romanian endemic l. hallersteinii baumg. is nested in a highly supported clade of l. pratensis accessions. molecular dating and ancestral range reconstruction the results of our bayesian molecular clock and ancestral range analyses suggest a mediterranean origin and a crown age of c. 23– myr for fabeae, with a best estimate for the associated substitution rate of substitutions per site per myr. we reconstruct a minimum of three dispersal events to the middle-atlantic islands and seven to the americas. none of the new world lineages originates from the atlantic islands. the oldest macaronesian lineage, the vicia scandens clade, split from a mediterranean ancestor - ma, subst/site/my and colonized the canary islands and madeira plus porto santo. the second dispersal led to the establishment of the vicia dennesiana lineage in the azores. the age estimate for this event is not very robust due to the low resolution in the v. cracca clade, where v. dennesiana is placed but it occurred probably more recently than the canary island lineage, between - ma, subst/site/my. the remaining colonization events are even more recent: the madeiran species or form vicia pectinata lowe split from the mediterranean vicia sativa - ma, whereas the canary island vicia chaetocalyx is nested in a clade of the mainly mediterranean vicia lutea and might have arrived only with the first human settlers. we reconstruct seven migration events to the new world: the vicia nigricans clade split from the eurasian vicia lineages - ma. this split is reconstructed as a long distance dispersal event from the mediterranean region to south america with high support but the vicia nigricans clade might also be sister to the caucasian v. crocea, which would indicate dispersal from asia via beringia. the ancestor of the hawaiian endemic vicia menziesii spreng. then dispersed from western america to hawaii - ma, subst/site/my; the north american vicia ludoviciana nutt. clade split from a mediterranean ancestral lineage - ma and dispersed across the atlantic, possibly floating in surface water; the mainly south american vicia section australes split from a mediterranean ancestral lineage - ma and is again most likely a case of ldd across the atlantic; the south american section notolathyrus split from a mediterranean ancestral lineage - ma, representing the third ldd event in the same time window of 9– ma; the large clade of north american species in lathyrus section orobus split from an asian ancestral lineage - ma, subst/site/my; colonization of the north american coasts by the lathyrus littoralis/l. japonicus lineage started c. 3– ma, subst/site/my; and finally the split between the north american vicia americana and its asian sister v. bungei is dated to - ma, subst/site/my. origin of the crop species in fabeae the pea, pisum sativum s. l. is sister to the eastern mediterranean pisum fulvum sibth. & sm. and both are sister to vavilovia formosa fed. alef.) and v. aucheri fed. from the caucasus mountains. the crown age of the pisum clade is estimated to - ma; the divergence between pisum and vavilovia dates back to - ma. lentil, lens culinaris ssp. culinaris, is nested among a group of very closely related taxa. their mostly allopatric distribution, morphological similarity and very recent divergence estimates suggest that they might be best treated as subspecies or varieties of lens culinaris. all together are sister to the mediterranean lens nigricans godr.. the split between the l. culinaris group and l. nigricans occurred - ma, whereas the stem lineage of lens might have split from its vicia ancestors - ma. faba bean or broad bean, vicia faba is sister to the himalayan v. paucijuga b. fedtsch., which is often treated as a subspecies of v. faba. both are nested in section vicia with an estimated stem age of 8– ma but this is not robust due to the lack of a well supported placement of the lineage in any of our phylogeny estimates. the ancient crop species vicia ervilia is placed in the ervilia clade that is here recovered as the sister group to all other fabeae. it split from its closest relatives in the v. sylvatica l. clade - ma. vicia sativa belongs in a group of closely related and insufficiently studied mediterranean taxa. in our ml and bayesian analyses, the v. sativa group is consistently reconstructed as sister to v. pyrenaica pourr. from which it split - ma. the economically most important species in the genus lathyrus, the ornamental sweet pea, l. odoratus, from southern italy and sicily, is sister to the wider mediterranean l. hirsutus l., from which it diverged - ma. finally, the minor crop l. sphaericus is sister to the mediterranean l. bauhinii genty clade, from which it diverged - ma. character evolution annual life form is reconstructed as ancestral in the tribe and a perennial life form evolved at least times independently followed by several reversals to annual life form. the ml ancestral character reconstruction indicates that a basic chromosome number of 2n= is most likely for the origin of the tribe. from that, reductions to 2n= or 2= and duplications to 2n= 2n= and 2= have occurred. major clades in fabeae seem to be characterized by common stylar pubescence patterns. from an originally evenly hairy style, the lathyrus-pisum-vavilovia clade evolved an adaxially hairy style, whereas some of the more derived vicia clades are dominated by an abaxially hairy style. there are, however, many exceptions: lathyrus saxatilis, for example, with an adaxially hairy style is deeply nested in vicia. the asian vicia subvillosa boiss. has a unique type of style with v-shaped hairy areas. it is unknown whether this character is shared with its african sister species v. malosana baker f., v. paucifolia baker, and v. claessensii de wild. another unique pattern is found in v. leucophaea, which has a densely hairy ring on its style that seems to have evolved from an abaxially hairy style. style shape, another traditional character for fabeae classification, varies little within the tribe: most species have a dorsiventrally compressed style, which is also reconstructed as most likely ancestral condition in the tribe. exceptions are most of the vicia species in section cracca, which have a laterally compressed style. a terete style has evolved six to seven times independently in the tribe: in the mediterranean v. pubescens, the eurasian v. hirsuta and vicia crocea, the north american v. leucophaea, and the east asian v. amurensis oett., v. tibetica prain ex c.e.e. fisch., v. nummularia hand.-mazz., and v. dichroantha diels. furthermore, pisum and vavilovia are characterised by a longitudinally folded style otherwise unknown in the tribe. discussion taxonomic implications the molecular data show that most of the currently recognized genera and subgenera, as well as many of the traditional sections are not monophyletic. pisum and vavilovia are sister groups and nested in lathyrus, which together with lens is nested in vicia. this grouping is also supported from the currently available whole plastid genomes for fabeae: lathyrus sativus and pisum sativum share four gene losses and the loss of the first intron of clpp and the cis-intron of rps. pisum and lathyrus furthermore share the phytoalexin pisatin, which was not found in vicia and lens. the two latter genera both had the phytoalexin wyerone in all analysed species except in vicia articulata and v. ervilia, which we find to be sister to all vicieae. thus the presence of wyerone could be a synapomorphy for vicia and lens. apart from alefeld’s concept of splitting the tribe into a multitude of tiny genera, the most radical solution to obtain a more natural classification of fabeae would be the transfer of all species of the four currently accepted smaller genera to a broadly circumscribed genus vicia. this, however, would require more than new combinations. an alternative solution would be to transfer pisum and vavilovia to a then monophyletic lathyrus. vicia section ervum, and v. pubescens) could be raised to genus-level; the name ervum l. with the lectotype e. tetraspermum l. is available. a monophyletic vicia could then be obtained by transferring lens and lathyrus saxatilis to vicia. the clade comprising vicia cypria kotschy, v. lunata boiss., v. ervilia, v. hirsuta, v. sylvatica, v. monanthos desf. and v. articulata hornem. kupicha) and v. quadrijuga p.h.davis very likely belong here too, so that a genus ervilia would probably comprise at least nine species. most of the sections also need to be revised if they are supposed to reflect monophyletic groupings: section cracca should include the former sections lentopsis, panduratae, perditae, variegatae, and volutae. section vicilla should be recircumscribed to include sections amurense and cassubicae. section mediocinctae could be lumped with section australes. section pedunculatae should be merged with section americanae. section vicia could be defined in a broader sense to accommodate sections atossa, bithynicae, faba, hypechusa, microcarinae, peregrinae, and wiggersia. in lathyrus, the clade including l. alpestris kit. ex reichb. and l. vernus bernh. could be split from section orobus. sections orobon and orobastrum could be lumped with section lathyrus. the circumscriptions of sections linearicarpus, lathyrus, and lathyrostylis all need to be slightly modified in order to obtain monophyletic groups. newly discovered fabeae clades that might warrant description of additional sections include the sister group of section subvillosae, comprising the african v. claessensii, v. malosana, and v. paucifolia; the pacific coast clade including v. nigricans, v. gigantea, and v. menziesii; vicia crocea, which might best be placed in a monotypic section even though additional work might reveal a sister group relationship to the v. nigricans clade. the results of our phylogenetic analyses show that lathyrus saxatilis is currently included in the wrong genus: the two accessions we have are both placed in the core vicia in our phylogeny and even though our data are not sufficient to pinpoint its exact position it should certainly be treated as vicia saxatilis tropea. the taxon was described as orobus saxatilis by ventenat but interestingly, it was already transferred to vicia in the early 20th century. kupicha discusses the morphological affinity to vicia but although expressing some doubts, the dorsally compressed and adaxially pubescent style led her to include it in lathyrus in a new monospecific section viciopsis. regarding the azorean endemic v. dennesiana, we reject kupicha’s concept of a monotypic section perditae and find that the species belongs in the mediterranean clade of section cracca, where it also fits well based on stylar morphology. the available herbarium specimens for this presumably extinct taxon show a striking overall morphological similarity to the v. nigricans group of the american pacific coasts and hawaii but our partial dna sequence data reject a close relationship. kupicha suggested that this species might be a biogeographic link explaining some of the amphi-atlantic distribution patterns in vicia but our analyses strongly suggest a single ldd event out of the mediterranean to the azores. our phylogeny estimates cast some doubt on species concepts applied in the canary islands and madeira: the canarian endemic vicia chaetocalyx is nested in macaronesian and mediterranean v. lutea accessions and it seems clear that the sequenced material should be assigned to the latter species because they are morphologically almost identical. however, our material came from a recently described population in gran canaria and not from the original type material collected by webb and berthelot and now in the florence herbarium, which should be used for further genetic study. a similar problem was reported in a recent study on an endemic bird species from the cape verde archipelago. the four canary and madeira endemics in the v. cirrhosa group show no genetic differences in any of the sequenced regions. since morphological differences are also minor, a re-evaluation of the group might be necessary. in contrast, we find a high genetic variability among the relatively few samples included from the v. sativa group, where additional macaronesian endemics might have been overlooked. lowe’s vicia pectinata for example, has been synonymized with the widespread v. sativa but we find three substitutions in the its region, which seem to be unique to lowe’s taxon. together with some morphological differences and the obvious isolation of the population on an oceanic island, there might be enough evidence to reinstate v. pectinata. however, a more detailed study of the vicia sativa group in macaronesian with several samples per island would be required to properly address this question. biogeographic history of the tribe the origin of fabeae is estimated to lie in the middle miocene. this result, however, could be expected since we constrained the vicia s.l. crown to ma under a normal prior distribution with standard deviation of million years. ldd events are relatively common in fabeae. we reconstruct ldd events over the period of c. million years, which translates into a rate of c. successful ldd events per million years. the same rate was found for cucurbitaceae but sampling density in that study was lower, so the cucurbit rate is very likely an underestimate. migration via greenland and the north atlantic land bridge is not an option in fabeae since the entire tribe is too young. migration across the beringian land bridge is likely for at least one lineage: the ancestors of the pacific coast species vicia nigricans, v. gigantea, and the hawaiian v. menziesii. however, since the lineage later managed to colonize the isolated hawaiian archipelago, ldd across the pacific from asia to the american pacific coast is also an option or, less parsimonious, ldd from the mediterranean to the american continent followed by spread to the west coast and extinction in the east. the next three fabeae lineages, vicia section australes, lathyrus section notolathyrus, and the v. ludoviciana clade, all reached the american continent in the same time window via ldd from the mediterranean region across the atlantic. this suggests favourable conditions for legume seed dispersal in the late miocene, a ‘window of opportunity’ in the sense of carine. with the opening of the bering strait, c. - ma, it became temporarily impossible to migrate to the americas over land but later reconnections might have allowed terrestrial migration of cold-adapted lineages. for the ancestors of lathyrus japonicus/l. littoralis, l. palustris, the large new world clade in lathyrus section orobus, and vicia americana we can thus not decide between terrestrial migration and ldd. more recently, there might have been some transport across the region by inuit, who use the roasted seeds to prepare drinks. for l. japonicus and l. palustris the most likely direction is a spread from asia to north america. in contrast, the v. americana lineage might have come the opposite way from north america to asia. both v. americana and v. bungei are sister to the european vicia onobrychioides l. and v. dumetorum and the ancestral lineage of the latter species might have spread into north america across the north atlantic. the now extinct azorean endemic vicia dennesiana might have reached the azorean archipelago in the north atlantic via ldd c. ma and the canary islands and madeira endemics of the vicia scandens clade colonized those archipelagos via ldd about ma. we can therefore reject the hypothesis of ancient stepping stone dispersal via the atlantic islands because all the island lineages are relatively recent arrivals compared to the age of macaronesia and none of the american lineages is nested in an atlantic island clade. in some cases our age estimates might also be biased old because of extinction events. the vicia dennesiana and v. scandens lineages could represent the last survivors of previously more species-rich eurosiberian clades in macaronesian refugia and might be even younger than estimated if the northwest african species of section cracca were included, for which we failed to obtain material. evolution of life form and floral morphology in fabeae ancestral character reconstruction shows that life form, stylar characters, and chromosome number are of limited value for systematic grouping of fabeae. style shape, a traditional character for fabeae classification, varies little within the tribe: most species have a dorsiventrally compressed style, which is also reconstructed as most likely ancestral condition in the tribe. the finding that an annual life form is most likely the ancestral state in the tribe is unexpected and rejects earlier hypotheses of multiple evolution of annual life form as an adaptation to range expansion into xeric habitats. it fits, however, with the result of the biogeographic analysis locating the region of origin in the mediterranean and not in the temperate or boreal forests, where a perennial life form would have been an advantage. a basic chromosome number of 2n= has already been suggested by other authors, an ancestral, evenly hairy, dorsiventrally compressed style fits with recent results of small-scale character reconstructions. origin of legume crops our analyses shed light on a group of generally overlooked mediterranean lathyrus species that apart from the caucasian vavilovia species might be very interesting for breeding of new pisum varieties due to benefitial traits including drought tolerance and perennial life form: l. gloeosperma, l. neurolobus boiss. & heldr., and l. nissolia all have affinities to the pisum plus vavilovia clade and might be included in breeding programs. the placement of v. faba far from the other members of section faba sensu kupicha and somewhere among v. oroboides wulfen, v. bithynica l., and the v. sativa-v. sepium clade is in agreement with earlier morphological, cytological and dna studies. vicia faba differs in chromosome number from most of the suggested relatives found in our analyses. vicia bithynica, v. oroboides, and v. sepium all have 2n= chromosomes, whereas v. faba has 2n=, which will make crossings for plant breeding purposes difficult. the lens clade has its closest relatives among early branching vicia clades followed by c. million years of independent evolution. while this could be a big obstacle for breeding efforts, the species of the african v. paucifolia complex and the asian v. subvillosa might be worth testing if initial screenings reveal benefitial traits. for the v. sativa complex, a sister group relationship to v. pyrenaica seems very likely and the species should be explored. the high sequence diversity detected among our accessions of v. sativa s.l. corresponds to earlier findings of karyological and aflp studies and a detailed revision of the group is recommended in order to detect the most useful growth forms.  based on nuclear and chloroplast phylogenies, we conclude that tribe fabeae evolved in the eastern mediterranean in the middle miocene. ancestral fabeae probably were annual plants with a chromosome number of 2n= and evenly hairy, dorsiventrally compressed style. from the mediterranean, the tribe expanded its range at least times into central and western europe and times to asia, twice to tropical africa, and at least seven times across the atlantic/pacific to the americas. the middle-atlantic islands were colonized four times but did not serve as stepping-stones for lineages colonizing the new world. our biogeographic analyses show that long distance dispersal events are relatively common in fabeae. current generic and infrageneric circumscriptions in fabeae do not reflect monophyletic groups and should be revised. 
tribe fabeae comprises about legume species, including some of the most ancient and important crops like lentil, pea, and broad bean. broad bean and its sister v. paucijuga originated in asia and might be sister to v. oroboides. relationships within the tribe, however, are incompletely known and previous molecular results conflicted with the traditional morphology-based classification. according to our ancestral character state reconstruction results, ancestors of fabeae had a basic chromosome number of 2n= an annual life form, and evenly hairy, dorsiventrally compressed styles. current generic and infrageneric circumscriptions in fabeae do not reflect monophyletic groups and should be revised. lentil 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. ma. the pisum clade is nested in lathyrus in a grade with the mediterranean l. gloeosperma, l. neurolobus, and l. nissolia. the middle-atlantic islands were colonized four times but apparently did not serve as stepping-stones for atlantic crossings. the extinct azorean endemic v. dennesiana belongs in section cracca and is nested among mediterranean species. fabeae originated in the east mediterranean region in the miocene ) and spread at least times into eurasia, seven times to the americas, twice to tropical africa and four times to macaronesia. 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. here we analyse the systematics, biogeography, and character evolution in the tribe based on plastid and nuclear dna sequences. 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. breeding efforts in legume crops rely on a detailed knowledge of closest wild relatives and geographic origin.
 tribe fabeae comprises about 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.  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 ) and spread at least times into eurasia, seven times to the americas, twice to tropical africa and four times to macaronesia. broad bean and its sister v. paucijuga originated in asia and might be sister to v. oroboides. lentil 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. 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= an annual life form, and evenly hairy, dorsiventrally compressed styles.  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. current generic and infrageneric circumscriptions in fabeae do not reflect monophyletic groups and should be revised. suggestions for generic level delimitation are offered. lathyruslegumeslentillong-distance dispersalmacaronesiapeapisumvicia 