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Reconstructing an historical pollination syndrome: keel flowers

Authors:
  • University of Portsmouth UK and University of Alaska Fairbanks

Abstract and Figures

Background Keel flowers are bilaterally symmetrical, pentamerous flowers with three different petal types and reproductive organs enclosed by keel petals; generally there is also connation of floral parts such as stamens and keel petals. In this study, the evolution of keel flowers within the order Fabales is explored to investigate whether the establishment of this flower type within one of the species-rich families, the Fabaceae (Leguminosae), preceded and could have influenced the evolution of keel flowers in the Polygalaceae. We conducted molecular dating, and ancestral area and ancestral state analyses for a phylogeny constructed for 678 taxa using published matK , rbcL and trnL plastid gene regions. Results We reveal the temporal and spatial origins of keel flowers and traits associated with pollinators, specifically floral symmetry, the presence or absence of a pentamerous corolla and three distinct petal types, the presence or absence of enclosed reproductive organs, androecium types, inflorescence types, inflorescence size, flower size, plant height and habit. Ancestral area reconstructions show that at the time keel flowers appeared in the Polygaleae, subfamily Papilionoideae of the Fabaceae was already distributed almost globally; at least eight clades of the Papilionoideae had keel flowers with a functional morphology broadly similar to the morphology of the first evolving Polygaleae flowers. Conclusions The multiple origins of keel flowers within angiosperms likely represent convergence due to bee specialization, and therefore pollinator pressure. In the case of the Fabales, the first evolving keel flowers of Polygaleae have a functional morphology that corresponds with keel flowers of species of the Papilionoideae already present in the environment. These findings are consistent with the keel-flowered Polygaleae exploiting pollinators of keel-flowered Papilionoideae. The current study is the first to use ancestral reconstructions of traits associated with pollination to demonstrate that the multiple evolutionary origins of the keel flower pollinator syndrome in Fabales are consistent with, though do not prove, mimicry.
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Ulueretal. BMC Ecology and Evolution (2022) 22:45
https://doi.org/10.1186/s12862-022-02003-y
RESEARCH ARTICLE
Reconstructing anhistorical pollination
syndrome: keel owers
Deniz Aygören Uluer1* , Félix Forest2, Scott Armbruster3 and Julie A. Hawkins1
Abstract
Background: Keel flowers are bilaterally symmetrical, pentamerous flowers with three different petal types and
reproductive organs enclosed by keel petals; generally there is also connation of floral parts such as stamens and
keel petals. In this study, the evolution of keel flowers within the order Fabales is explored to investigate whether
the establishment of this flower type within one of the species-rich families, the Fabaceae (Leguminosae), preceded
and could have influenced the evolution of keel flowers in the Polygalaceae. We conducted molecular dating, and
ancestral area and ancestral state analyses for a phylogeny constructed for 678 taxa using published matK, rbcL and
trnL plastid gene regions.
Results: We reveal the temporal and spatial origins of keel flowers and traits associated with pollinators, specifi-
cally floral symmetry, the presence or absence of a pentamerous corolla and three distinct petal types, the presence
or absence of enclosed reproductive organs, androecium types, inflorescence types, inflorescence size, flower size,
plant height and habit. Ancestral area reconstructions show that at the time keel flowers appeared in the Polygaleae,
subfamily Papilionoideae of the Fabaceae was already distributed almost globally; at least eight clades of the Papil-
ionoideae had keel flowers with a functional morphology broadly similar to the morphology of the first evolving
Polygaleae flowers.
Conclusions: The multiple origins of keel flowers within angiosperms likely represent convergence due to bee
specialization, and therefore pollinator pressure. In the case of the Fabales, the first evolving keel flowers of Polygaleae
have a functional morphology that corresponds with keel flowers of species of the Papilionoideae already present in
the environment. These findings are consistent with the keel-flowered Polygaleae exploiting pollinators of keel-flow-
ered Papilionoideae. The current study is the first to use ancestral reconstructions of traits associated with pollination
to demonstrate that the multiple evolutionary origins of the keel flower pollinator syndrome in Fabales are consistent
with, though do not prove, mimicry.
Keywords: Floral evolution, Pollination, Character reconstruction, Fabaceae
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Background
Keel flowers sensu Westerkamp are bilaterally sym-
metrical (zygomorphic, monosymmetric), pentamerous
flowers with three different petal types, with the repro-
ductive organs enclosed by keel petals and generally with
connation of floral parts such as stamens and keel pet-
als [110]. Keel flowers are dominant in two species-rich
lineages within Fabales, tribe Polygaleae Chodat (Polygal-
aceae Hoffmanns. & Link) and subfamily Papilionoideae
L. (DC.) (Fabaceae Lindl.) [11, 12]. Indeed, this flower
type is typical of subfamily Papilionoideae of Fabaceae,
and the prevalence of keel flowers in Papilionoideae has
prompted some to refer to them as papilionate flowers.
Fabaceae is the third largest angiosperm family with
approximately 765 genera and 19,500 species [1316].
Open Access
BMC Ecology and Evolution
*Correspondence: d.aygoren@ahievran.edu.tr
1 School of Biological Sciences, Lyle Building, University of Reading,
Whiteknights, Reading, Berkshire RG6 6BX, UK
Full list of author information is available at the end of the article
Page 2 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
e keel-flowered subfamily, Papilionoideae, includes
almost 72% of Fabaceae species, ca. 14,000 species in 504
genera [8, 14, 15]. Similarly, within Polygalaceae (with
approximately 1000 species in 20 genera), tribe Polyg-
aleae holds 80% of the species richness of the family with
ca. 800 spp. [1, 5, 17]. In the Fabaceae, keel flowers are
also found outside of Papilionoideae, in Cercidoideae,
Dialioideae and Caesalpinioideae: Cercis, Poeppigia pro-
cera C. Presl and Peltophorum Vogel (Benth.) [18, 19].
Other, unrelated families including species with keel
flowers are the Ranunculaceae, Onagraceae, Sapindaceae,
Trigoniaceae, Geraniaceae, Tropaeolaceae, Solanaceae,
Acanthaceae and Commelinaceae, but they have fewer
keel-flowered species than either Fabaceae or Polygal-
aceae [9].
In general, the evolution of keel flowers within
Fabaceae, Polygalaceae and different clades of angio-
sperms has been attributed to bees [9, 2022], but par-
ticularly to skilled and strong bees [9, 18, 20, 21, 2325].
Less commonly, large and brightly coloured flowers may
be bird-pollinated (e.g., Mucuna Adans., Erythrina L.),
or butterfly-pollinated (e.g., Berlinia grandiflora Vahl
Hutch. & Dalziel), and a few keel-flowered species with
specific scents are beetle (e.g., Aotus lanigera A. Cunn. ex
Benth.) or fly-pollinated (e.g., Apios americana Medik.)
[18, 26, 27]. Specific adaptations of keel flowers are asso-
ciated with bee pollination. For example, hiding pollen
inside keel flowers protected by a tripping mechanism
may limit pollen loss associated with pollen theft [9, 10,
18, 19, 21, 28]. Furthermore, many Papilionoideae flow-
ers exhibit different primary and secondary pollination
mechanisms such as valvular, pump, explosive and brush
mechanisms, which also ensure accuracy and efficiency
of pollen deposition and so limit the pollen waste ([29]
and references therein). In these ways, pollen is hidden
in the deepest part of the flower, and pollen is transmit-
ted to, for example, a bee’s head, or above the insertions
of the legs or wings, so pollen cannot be easily removed
during grooming [9, 10, 30, 31]. is specific position of
the pollen (i.e., location of the pollen on different bee spe-
cies, such as back of the head, under the mandible or on
inner side of mandible) is also another precaution against
non-pollinator visitors [30]. us, the evolution of keel
flowers has been referred to as an adaptive response to
bees; the keel flowers evolved not just to attract bees but
also to protect the pollen from bee robbery [9, 18, 22, 31,
32]. e independent evolution of the keel flower syn-
drome in the Fabales is likely to have secured pollination
and promoted cross-pollination of keel-flowered species
[33, 34].
Previously, the morphology and development of keel
flowers of two species-rich clades of Fabales, Papilio-
noideae and Polygaleae, have been compared (e.g., [1, 17,
22, 35]). In both clades, keel flowers are at least super-
ficially similar, they both are 5-cyclic and 5-merous, and
consist of three parts, a standard for visual attraction,
two wings as a landing platform and a keel to conceal
the pollen from pollinators [8, 9, 18, 22, 35]. However,
while the functions of these parts are the same in the
two groups of Fabales, the developmental origins are
different. e standard (flag) consists of a single median
petal in Fabaceae but is composed of two lateral sepals
in Polygalaceae. e wings are formed by two petals in
Papilionoideae but consist of two petaloid lateral sepals
in Polygalaceae [22]. One or two fused lower lateral pet-
als serve as the keel in legumes, but the keel comprises
one median petal in Polygalaceae, since Polygalaceae keel
flowers consist of five petals, only three of which are fully
developed, and the abaxial one forming an asymmetric
keel [5, 22, 3638]. Keel flowers of Papilionoideae have
ten stamen filaments and a single carpel, but Polygal-
aceae keel flowers have eight filaments and a syncarpous
gynoecium which consists of two carpels [22, 35]. us,
keel flowers in the two families represent a superficial
functional and morphological convergence, rather than a
homologous similarity [1, 17, 22, 35].
Although the flowers of these two Fabales lineages are
not homologous, their striking similarity has led some
authors to propose that this shared similarity is more
than convergance on a floral syndrome. Bello etal. [17]
proposed that the rapid diversification of the tribe Polyg-
aleae, previously documented by Forest etal. [39], may
have been prompted “because pollinators of pre-existing
papilionoid legume flowers were immediate and effec-
tive pollinators of the later-evolving papilionoid flowers
of Polygaleae”. Indeed, Bello etal. [17] were not the first
to propose such a scenario. Pseudo-papilionoid flowers
of Cercis L. (sensu Polhill etal. [19]) have some similari-
ties with Papilionoideae keel flowers such as a bilater-
ally symmetrical corolla, three different petal types, and
enclosed stamens and gynoecium, prompting Tucker [7]
to hypothesize a mimicry relationship between Cercis
keel flowers and Papilionoideae flowers. Tucker [7] sup-
posed that Cercis likely evolved in an environment where
keel flowers were already present. However, whether the
later-evolving keel flowers benefitted from pollinators
familiar with the keel-flowers of earlier-evolving clades is
an open question.
To meet the criteria which evidence floral mimicry,
species should share a common pollinator which freely
moves between two taxa, share display traits appar-
ent to the pollinators (e.g., colour, UV patterns, nectar,
scent and size), there should be a reproductive benefit
to one or both species, the species should have areas of
sympatry, overlapping flowering phenology, and maybe
most importantly the mimic should be more successful
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Ulueretal. BMC Ecology and Evolution (2022) 22:45
in terms of reproduction because of its resemblance to
the model, so the mimic receives more visits when it co-
occurs with the model [4043]. Aside from numerous
examples of mimicry involving the Orchidaceae (e.g.,
[44]), floral mimicry is evidenced for angiosperm and
gymnosperm beetle pollinated plants [45] and Turn-
eraceae and Malvaceae flowers [40], with the study of
oil-offering plants the first to scrutinise putative floral
mimicry in deep evolutionary time [46]. Identifying older
and younger oil-offering clades, Renner and Schaefer [46]
suggested that ancestral reconstructions were consist-
ent with a gradual niche broadening, but that attributing
each later appearance to mimicry would depend on stud-
ies of pollinator behavior. For inferences based on phylo-
genetic reconstructions, in the absence of observations of
pollinator behaviour, we therefore refer to findings con-
sistent with a mimicry, but we cannot provide evidence
of mimicry from evolutionary reconstructions alone.
However, though this was not the case, we could have
refuted mimicry if keel flowers of younger clades did not
share pollination syndromes or were not sympatric with
species in existing clades.
e aim of the current study is to determine whether
evolution of the keel flowers of Polygaleae and Papilio-
noideae are consistent with a mutualistic relationship
by characterising the early evolution of the keel flowers
of these two species-rich clades. Specifically, we set out
to confirm whether keel flowers appeared first in Papil-
ionoideae, whether the keel-flowered Papilionoideae
were likely to have been present in the geographical areas
where the keel-flowered Polygaleae first appeared, and
whether the functional morphology of the keeled Papilio-
noideae flowers was broadly similar to the morphology of
the first evolving Polygaleae flowers. If these criteria are
met, though not proving mutualism, this would be con-
sistent with a mutualistic relationship, with Polygaleae
flowers benefitting from existing Papilionoideae polli-
nators due to their resemblance to pre-existing Papilio-
noideae keel flowers.
Results
Molecular dating analysis
e divergence time analysis (Additional file 1:
S1) generated a ((Fabaceae+Polygalaceae)
(Surianaceae+Quillajaceae)) topology within mono-
phyletic Fabales (1.00 PP). Within Polygalaceae, tribe
Moutabeae was not monophyletic (Fig.1). However, both
tribe Polygaleae and tribe Carpolobieae were strongly
monophyletic (0.96 and 1.00 PP, respectively). On the
other hand, a (((Papilionoideae+Caesalpinioideae) Dial-
ioideae) (Detarioideae (Duparquetioideae+Cercidoid
eae))) topology is estimated within Fabaceae. Duparque-
tia Baill. (Duparquetioideae) was sister to monophyletic
Cercidoideae (1.00 PP) with posterior probability of only
0.65. Monophyletic Detarioideae (1.00 PP) was sister to
this clade with moderate support (0.82 PP). Monophyl-
etic Caesalpinioideae (1.00 PP) was sister to monophyl-
etic Papilionoideae (1.00 PP) with posterior probability of
1.00, and monophyletic Dialioideae (1.00 PP) was sister
to this clade (1.00 PP).
e crown age of Fabales is estimated to be
at least 74.97 Ma (95% HPD 69.3–76.7); the
(Surianaceae+Quillajaceae) crown node as 68.62 Ma
(95% HPD 50.2–73.9); Surianaceae crown node as
47.59Ma (95% HPD 33.2–53.1); Fabaceae crown node as
71.89Ma (95% HPD 67.9–69.3), subfamily Papilionoideae
crown node as 67.19Ma (95% HPD 62.5–64.9); Polygal-
aceae family crown node as 63.59Ma (95% HPD 58.2–
62.7); and 45.16Ma (95% HPD 38.8–44.7) for the crown
node of tribe Polygaleae. Additionally, the molecular dat-
ing analyses yielded a 54.80 Ma (95% HPD 55.1–48.1)
crown age for the crown Cercidoideae node, 57.66 Ma
(95% HPD 55.6–53.1) for the crown Detarioideae node,
38.28Ma (95% HPD 44.7–27.1) for the crown Dialioideae
node, 64.46Ma (95% HPD 64.1–58.2) for the crown Cae-
salpinioideae node, and 69.14Ma (95% HPD 68.5–63.3)
for Duparquetioideae.
e first node with keel flowers in the Polygalaceae was
46.98–45.16Ma (crown age of tribe Polygaleae). e evo-
lution of keel flowers coincided with the evolution of the
keel flower tribe, Polygaleae (99.6%) (Table1).
Based on the reconstructions of the timing of keel
flower origin in Polygalaceae (46, 98–45, 16 Ma), we
selected the Papilionoideae nodes which were extant in
South America at that time to test whether a mimicry
between Polygalaceae and Papilionoideae was plausible.
To be conservative, we expanded the time frame up to
49Ma. In this logic, there were 16 clades in total. How-
ever, out of these 16 nodes, one originated between ~ 49
and 45 and could not be included here due to lack of
information. We also excluded seven clades due to their
geographic distribution (not included in Table1). For the
eight remaining relevant clades, the ancestral area and
ancestral state for each of the 11 pollination syndrome
characters were reconstructed. ese clades are shown in
Fig.1, listed in Appendix 2, and the ages of these nodes
are reported in Table1.
Ancestral area analyses
e Lagrange analyses indicated a possible South Ameri-
can origin for the keel flowered Polygalaceae (67% G, 18%
EG, 14%E) (Table1, Additional file2: S2). For the eight
Papilionoideae clades hypothesized, ancestral areas are
listed in Table1.
Additionally, the Lagrange analyses support a South
American origin for the subfamily Papilionoideae (100%)
Page 4 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
and Africa+South American origin for the Fabaceae
(75% BG, 14% BEG, 11% G). A South American origin
was also suggested by Lagrange analysis for the origin of
Fabales with low support (30% G, 29% BEG, 20% BG).
Ancestral state analyses
e ancestral floral type for Polygalaceae was non-keeled
(92%), whilst the ancestral flower type of tribe Polygaleae
was keeled (99.6%) with three distinct petal+sepal types
(89.6%), enclosed reproductive organs (99.9%), fused sta-
mens (98%), probably pentamerous petals+sepals (63%)
and bilateral symmetry (79%) (Table1). e most recent
common ancestor (MRCA) of tribe Polygaleae most pos-
sibly had vertical inflorescences (e.g., raceme, panicle,
spike and thyrse) (81%), and a small habit (e.g., herb, 53%;
however, the possibility of a medium-sized habit was also
high at 41%). e ancestral floral size of tribe Polygaleae
was between 2.9 and 10.5mm, and ancestral plant height
was between 76cm and about 9.1m.
ere were eight clades of Papilionoideae with ances-
tral morphologies that might have allowed pollinators to
move freely between the flowers of these and tribe Polyg-
aleae flowers. ese clades were clades 2–8 (Table 1),
based on shared pollination syndrome characters. Where
characters were not a perfect match, but differences were
not likely to significantly impact pollinators, we consid-
ered shared pollinators a possibility. For example, ances-
tral reconstruction of clade 2 suggested these plants were
of similar height to the ancestors of tribe Polygaleae, so
despite the different habits we considered it possible
that ancestors of this clade shared pollinators with tribe
Polygaleae. Similarly, ancestral reconstructions of free
stamens in clades 2 and 8 were not considered to have
significant impact on pollinator behavior because other
ancestral floral characteristics of these two clades match
the ancestral flowers of tribe Polygaleae, and keel flowers
with free stamens still exist in Papilonideae (e.g., Bolu-
santhus and Baptisia).
Fig. 1 The origins of Papilionoideae clades (Clade 1–8) which evolved during 49–45.16 Ma and the origin of the evolution of keel flowers within
Polygalaceae. Posterior probabilities for the key nodes are indicated. Four Fabales families, six Fabaceae subfamilies, Cercis and Xanthophyllum are
indicated. Standard error bars were excluded from the figure for clearer presentation. Letters and numbers in red correspond to the calibration
points. Scale bar in million years
Page 5 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
Table 1 Results of ancestral area, age, ancestral flower type, ancestral floral symmetry, the presence or absence of a pentamerous corolla (petals+sepals in Polygalaceae), the
presence or absence of three distinct petal types (petals+sepals in Polygalaceae), the presence or absence of enclosed reproductive organs, ancestral androecium type, ancestral
inflorescence type, ancestral floral size, ancestral height and habit analyses for tribe Polygaleae, and clades 1–8 of Papilionoideae
Name of the
clade Geographic
origin Age (~ my) Ancestral
oral type Floral
symmetry Pentamerous
petals
(+ sepals)
Three
distinct
petal
(+ sepal)
types
Enclosed
reproductive
organs
Androecium
type Inorescence
type Flower size
(mm) Height (m) Habit
Tribe Polyg-
aleae (Polyg-
alaceae)
67% G
18% EG
14% E
45.16
(~ 38.8–44.7) 99.6% A
(99.3–99.9%) 21% A
(20.2–21.5%)
79% B
(78.5–79.1%)
63% A
(62.7–63.2%)
37% B
(36.9–37.3%)
89.6% A
(89.3–89.8%)
10.2% C
(10–10.5%)
99.9% A
(99.7–100%) 2% A
(1.6–2.4%)
98% B
(97.6–98.4%)
81% A
(79.7–81.8%)
1% B
(1.2–1.5%)
18% C
(16.9–18.9%)
2.87–10.5
(2.29–11.7) 0.76–9.1
(0.45–9.8) 6% A
(5.5–6.1%)
41% B
(40.5–41.8%)
53% C
(52.2–53.9%)
Clade 1
(Mrca of
Candolleo-
dendron and
Swartzia
100% G 48.07
(~ 44.0–46.0) 99.9% B
(99.9–100%) 6% A
(6.1–6.3%)
94% B
(93.7–94%)
1% A
(0.5–0.6%)
99% B
(99.3–99.4%)
94% B
(93.9–94.1%)
6% C
(5.9–6.1%)
100% A
(100%-100%) 100% A
(100%-100%) 97% A
(96.9–97.3%)
1% B
(0.5–0.6%)
2% C
(2.1–2.5%)
X2.1–22.8
(1.9–23.3) 98% A
(98.1–98.2%)
1% B
(0.9–1%)
1% C
(0.8–0.9%)
Clade 2
(Mrca of Peri-
copsis and
Bowdichia)
66% G
34% EG 45.46
(~ 30.1–53.8) 99.9% A
(99.8–100%) 2% A
(1.9–2%)
98% B
(98–98.1%)
96% A
(96.1–96.3%)
4% B
(3.7–3.9%)
41% A
(39.6–42.3%)
58.2% C
(56.9–59.5%)
99.8% A
(99.7–99.9%) 99.9% A
(99.9–100%) 97% A
(96.5–97.4%)
3% C
(2.5–3.4%)
11.6–24.5
(11.2–25.4) 8.1–34
(7.9–34.4) 95% A
(94.6–95.6%)
1% B
(0.4–0.5%)
1% C
(0.3–0.5%)
Clade 3
(Mrca of
Adesmia and
Zornia)
100% G 47.09
(~ 36.6–51.5) 99.9% A
(99.9–100%) 24% A
(23.3–23.7%)
76% B
(76.3–76.7%)
61% A
(60.7–61%)
39% B
(39–39.3%)
81.1% A
(80.9–81.3%)
1.3% B
(1.2–1.3%)
17.6% C
(17.4–17.8%)
99.9% A
(99.9–100%) 4% A
(4.3–4.4%)
96% B
(95.6–95.7%)
81% A
(79.7–81.3%)
6% B
(5.4–6.1%)
1% C
(1.3–1.4%)
8.3–16
(7.7–17.5) 2.9–10.8
(2.5–11.7) 29% A
(28.3–29.7%)
28% B
(27.3–28.6%)
43% C
(42.3–43.9%)
Clade 4
(Mrca of
Weberbau-
erella and
Humularia)
100% G 48.44
(~ 42.8–47.3) 99.9% A
(99.9–100%) 7% A
(6.4–6.6%)
93% B
(93.4–93.6%)
78% A
(77.5–78%)
22% B
(22–22.5%)
95.4% A
(95.2–95.6%)
4.5% C
(4.3–4.7%)
99.9% A
(99.9–100%) 99.9% B
(99.8–100%) 91% A
(90.8–91.9%)
2% B
(1.7–2.1%)
7% C
(6.2–7.3%)
8.3–20
(7.9–21.1) 3.2–19.6
(2.9–20.2) 3% A
(3.1–3.2%)
95% B
(94.8–95%)
2% C
(1.9–2%)
Clade 5
(Mrca of
Humularia
and Dalber-
gia)
100% G 47.63
(~ 42.8–47.3) 99.9% A
(99.9–100%) 7% A
(6.6–6.7%)
93% B
(93.1–93.4%)
78% A
(77.5–78%)
22% B
(22–22.5%)
93.3% A
(93–93.6%)
6.6% C
(6.4–6.9%)
99.9% A
(99.9–100%) 99.9% B
(99.8–100%) 89% A
(88.2–89.5%)
3% B
(2.5–2.9%)
8% C
(7.9–9%)
8–18.74
(7.5–19.8) 2.9–19
(2.7–19.5) 4% A
(4.1–4.4%)
93% B
(92.9–93.3%)
3% C
(2.5–2.7%)
Page 6 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
In each column, the bold value indicates the highest probability for each character. Decimals are rounded to the nearest whole number to avoid fractional points. Possibilities less than 1% are not included, and the
ancestral area analyses up to three possible origins are reported. Nodes that do not fulll the criteria of a mimicry scenario are shaded. Crosses (X) indicate that the corresponding analysis was not employed due to lack
of information. Ages (My) are mean and node heights from HPD intervals at 95% (upper and lower) and 95% condence intervals for the discrete and continuous characters are provided within parantheses. For the
ancestral ower size and plant height analyses, both the smallest and largest sizes are indicated. Geographic area abbreviations: A: Eurasia; B: Africa; C: Madagascar; E: Australia including New Guinea, New Caledonia and
New Zealand; F: North America; G: South America including Central America and H: the Indian subcontinent [47]. Other abbreviations are explained in Table3
Mrca most recent common ancestor, my million years, mm millimeter, m meter
Table 1 (continued)
Name of the
clade Geographic
origin Age (~ my) Ancestral
oral type Floral
symmetry Pentamerous
petals
(+ sepals)
Three
distinct
petal
(+ sepal)
types
Enclosed
reproductive
organs
Androecium
type Inorescence
type Flower size
(mm) Height (m) Habit
Clade 6
(Mrca of
Pictetia and
Humularia)
100% G 46.44
(~ 38.4–46.6) 99.9% A
(99.8–100%) 16% A
(15.3–15.7%)
84% B
(84.3–84.7%)
67% A
(66.7–67.2%)
33% B
(32.8–33.3%)
83.6% A
(83.4–83.8%)
15.8% C
(15.6–16.1%)
99.9% A
(99.9–100%) 99.5% B
(95.4–95.6%) 85% A
(83.7–85.4%)
2% B
(2.5–2.9%)
13% C
(11.9–13.5%)
8.2–20.5
(7.7–21.6) 2.8–19.1
(2.5–19.7) 4% A
(4–4.3%)
84% B
(83.2–84.1%)
12% C
(11.7–12.3%)
Clade 7
(Mrca of
Clitoria and
Dalbergiella)
48% B
45% G 48.35
(~ 38.5–50.4) 99.8% A
(99.6–100%) 27% A
(26.5–26.9%)
73% B
(73.1–73.5%)
60% A
(60.3–60.5%)
40% B
(39.5–39.7%)
77.5% A
(77.3–77.7%)
20.5% C
(20.4–20.7%)
99.9% A
(99.9–100%) 1% A
(1.4–1.5%)
99% B
(98.5–98.6%)
43% A
(43.1–43.3%)
44% B
(43.7–44.1%)
13% C
(13.1–13.4)
10.3–25.4
(9.7–26.8) 4.2–16.6
(3.9–17.4) 46% A
(45.9–46.2%)
41%B
(40.4–40.8%)
13%C
(13.1–13.5%)
Clade 8
(Mrca of
Mundulea
and Agan-
ope)
35% BG
29% B
22% G
47.09
(~ 40.1–46.5) 98% A
(98–98.3%)
2% B
(1.8–2%)
25% A
(23.6–26.6%)
75% B
(73.4–76.4%)
65% A
(64–66.1%)
35% B
(33.9–36%)
87.4% A
(86.5–88.3%)
12.3% C
(11.5–13.2%)
99.6% A
(99.4–99.8%) 90% A
(88.8–90.9%)
10% B
(9.1–11.2%)
90% A
(89.6–91.1%)
4% B
(3.1–4%)
6% C
(5.6–6.6%)
10–20.3
(9.6–21.4) 7.4–17.4
(7.2–17.9) 63% A
(61.7–64.4%)
23% B
(21.8–23.8%)
14% C
(13.6–14.9%)
Page 7 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
Discussion
To determine whether the first-evolving Polygalaceae
keel flowers were functionally similar to existing Papilio-
noideae keel flowers, and might have evolved in an envi-
ronment where functionally similar Papilionoideae keel
flowers were present, we carried out temporal, spatial
and trait analyses.
e divergence-time analysis was congruent with previ-
ous studies (e.g., [12, 39]), with short internal branches of
Fabales reflecting the rapid radiation already highlighted
for this clade [12, 48, 49]. e divergence-time analysis
also showed that keel flowers in crown Papilionoideae
67.19Ma (95% HPD 62.5–64.9) evolved before the origin
of Polygalaceae (63.59Ma, 95% HPD 62.7–58.2Ma) and
tribe Polygaleae (45.16, 95% HPD 44.7–38.8 Ma), even
if we accept Xanthophyllum as polymorphic in terms of
the presence or absence of keel-flowers [50]. Similarly,
even accepting a keel flowered ancestor for Polygalaceae
(Moutabea Aubl. excluded), the evolution of keel flowers
within crown Papilionoideae was still earlier than in the
crown Polygalaceae (56.87Ma, 95% HPD 62.7–58.2Ma).
We are confident that keel flowers within Papilionoideae
evolved many millions of years (22.03–10.32Ma) before
the evolution of keel flowers in Polygalaceae.
Our ancestral area reconstructions show that at the
time keel flowers appeared in the Polygaleae, the Papil-
ionoideae was distributed almost globally. ere were
eight clades in South America at the time that the keel-
flowered Polygaleae originated in this continent. Trait
analyses show that at least seven of these clades are con-
sistent with a mutualistic relationship. In other words, at
least for these seven nodes, the functional morphology of
the keeled Papilionoideae flowers was broadly similar to
the morphology of the first evolving Polygaleae flowers.
us, Polygaleae flowers might have benefited from exist-
ing Papilionoideae pollinators that were already visitors
to Papilionoideae keel flowers.
When pollinators are available, “a plant should special-
ize on the most effective and/or most abundant pollina-
tor” [51, 52]. In this case, if Papilionoideae keel flowers’
pollinators are readily available, exploratory visits by
these effective and/or abundant pollinators to Polygaleae
flowers resembling Papilionoideae keel flowers might
have been the first stage of this ancient mimicry [46]. In
this case, if the Polygaleae keel flowers were rewardless,
this could be a type of Batesian mimicry; however, if the
Polygaeae keel flowers possessed abundant amount of
reward, and this mutualism could be beneficial to both
model and the mimic, this could be a Müllerian mim-
icry. Yet, whether Polygaleae keel flowers were more or
less rewarding than the keel flowers of Papilionoideae is
an open question. We suppose that Polygalaeae exploited
existing Papilionoideae pollinators, but co-flowering
might have increased the pollination rate of both Papil-
ionoideae and Polygaleae keel flowers at that time [53].
However, since we are reconstructing a scenario that
occured millions of years ago, it is almost impossible to
determine the community interactions that occurred
among existing plants and their pollinators. Without
knowing these community interactions robust evidence
for mimicry is elusive, because in a mimicry scenario the
model is abundant in the environment, but the mimic is
in low densities, while in a convergent evolution scenario
both mimic and model are found in similar densities [40].
Pollinator shifts can cause diversification [54, 55], and
a shift to long-tongued bees might have been one key
innovation associated with the diversification rate shift
already documented for the stem lineage of Polygaleae
[39]. Indeed, pollinator shifts account for ca. 25% of doc-
umented divergence events in the Orchidaceae plus ca.
25% of other angiosperms [54, 56]. Subsequent to the ori-
gin of keel flowers, successive ecological opportunities to
colonize new habitats [54], expanding the geographic and
niche range [57, 58] has likely accompanied the diversi-
fication of the keel-flowered lineages. For the subfamily
Papilionoideae, on the other hand, radiations in multiple
lineages have driven increases in species richness [59]. In
the current study, we did not perform any diversification
rate analyses for Papilionoideae, and whether keel flow-
ers are key innovations in this subfamily remains an open
question.
Complex flowers, such as keel and bilabiate flowers
(i.e., dorsiventral blossoms sensu [9, 10], are hypoth-
esized to have evolved to hide protein rich pollen from
bees by blocking the entrance of the flower, and at the
same time, to ensure pollination by attaching pollen to
either the dorsal (bilabiate or lip blossoms) or ventral
(most keel blossoms) side of bees [9, 10, 20, 30, 51, 54].
Westerkamp [9] and Westerkamp & Claßen-Bockhoff
[10] stated that, in terms of pollination, while the evo-
lution of keel flowers is much more effective, keel and
lip flowers are fundamentally the same. While lip flow-
ers evolved in at least 38 angiosperm families (including
Fabaceae), keel flowers evolved at least 16 times within
10 different orders independently within angiosperms.
However, excepting Trigoniaceae and Fumarioideae,
there are fewer species of keel flowers in angiosperm
families other than in Fabales [9, 22]. Some genera or
species of these other families have flowers with nota-
ble morphological similarities to legume keel flowers,
such as Pelargonium rapaceum (L.) L’Hér. (Geraniaceae),
Calceolaria L. (Lamiales) and Monopsis lutea (L.) Urb.
(Campanulaceae) with enclosed reproductive organs and
standard(s); Schizanthus Ruiz & Pav. (Solanaceae) with
a standard, wings and keel petals [7, 9, 18, 19, 60]. Col-
linsia Nutt. (Lamiales) with a standard, wings, a keel and
Page 8 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
hidden reproductive organs, has greatest similarities with
Papilionoideae and Polygaleae keel flowers [9, 6063]. In
Aconitum L., pollen is also deposited on the ventral side
of the pollinator during pollination. In Corydalis cava
(L.) Schweigg. & Körte on the other hand, lateral pet-
als enclose the reproductive organs to hide pollen from
bumblebees, as in Papilionoideae keel flowers [28]. Both
Hyptis Jacq. (Lamiaceae) and Levenhookia R.Br. (Stylidi-
aceae) have spring-loaded keels which cause explosive
release of fertile parts when triggered by pollinators.
e similarities of these keel flowers have been attrib-
uted to convergence due to bee specialization, and there-
fore, pollinator pressure [9, 54, 64, 65]. In this case, not
only the morphological characters of keel flowers but also
the choices of pollinators (e.g., exact location of pollen on
bees’ body where it cannot be removed easily, enclosed
reproductive organs which supports the minimum loss
of pollen by keeping it away from non-functional visi-
tors, visual clues such as bilateral symmetry, a standard
for visual attraction, a landing platform and a standard
for visual impact) might have canalized the convergent
evolution of keel flowers within unrelated angiosperm
clades. Here, for example, keel flowered Collinsia het-
erophylla Graham (Lamiales), Aconitum napellus subsp.
lusitanicum Rouy (Ranunculales) and Corydalis cava
(Ranunculales) are also pollinated by similar pollinators
as the keel flowers of Papilionoideae [6062, 6669].
Keel flowers might have evolved to host these efficient
pollinators (strong bees or long-tongued bees of Apidae
and Megachilidae families) [63, 67, 70]. Indeed, Ruxton
and Schaefer [71] suggested, instead of mimicry, that
convergent evolution (i.e., pollination syndromes sensu
Faegri andVan der Pijl [25]) driven by shared pollina-
tors could be a more plausible explanation not only for
the evolution of keel blossoms within unrelated lineages
of angiosperms [9, 58, 62, 7274] but also for most sup-
posed plant mimics. Moreover, since the hymenopterans
were already highly diversified at that time, a competition
free space with similar morphologies would have helped
Polygalaceae keel flowers to benefit this new area and
radiate ([54, 75], Anonymous Reviewer 2, pers. comm.).
For instance, for the orchid genus Ophrys L., it was sug-
gested that diversification of the genus began after the
well establishment of hymenopterans and because of
the coevolution of plants and their pollinators, adaptive
radiation has caused a species burst in the genus [75].
Furthermore, when two species share the same pollinator
with the same flowering time and distribution, not only
convergence of some floral traits (e.g., shape and color)
to attract the same suit of available pollinators, but also
divergence in others (i.e., different pollination niches)
(e.g., odor) to prevent hybridization is common [75, 76].
Indeed, this floral adaptation under pollinator pressure
(i.e., sharing the same suits of pollinators, 10) might have
caused tribe Polygaleae to modulate its pollinator niche
(Anonymous Reviewer 2, pers. comm.), and evolution of
a similar floral bauplan with the Papilionoideae keel flow-
ers. erefore, in order to better understand keel flower
evolution, it is necessary to conduct detailed comparative
studies on keel flowers and their pollinators. For instance,
while tripping mechanisms are reported for keel-flow-
ered Polygalaceae [77], for other keel-flowered lineages
among angiosperms the situation is unknown. Similarly,
choice tests of keel flower pollinators, especially with
naïve bees may reveal whether these pollinators move
freely between different angiosperm keel flowers or not,
and whether mimics (i.e., Polygalaceae keel flowers)
receive more visits when they co-occur with the model
(i.e., Fabaceae keel flowers), or mimics are more success-
ful in terms of reproductive biology with the presence of
legume keel flowers or not [40].
Conclusions
To determine whether the first-evolving Polygalaceae
keel flowers were functionally similar to existing Papil-
ionoideae keel flowers and pollinated by similar pollina-
tors, we carried out molecular dating, ancestral area and
ancestral state analyses. e current study is the first to
use ancestral reconstructions of traits associated with
pollination to demonstrate that the multiple evolutionary
origins of the keel flower pollinator syndrome in Fabales
are consistent with, though do not prove, mimicry. Our
results have shown that Polygaleae flowers might have
benefited from existing Papilionoideae pollinators that
were already visitors to Papilionoideae keel flowers.
However, further research is needed to establish a bet-
ter understanding of the context of the pollinators of keel
flowers of different angiosperm clades. Whether other
angiosperm clades that have keel flowers might have ben-
efited from existing pollinators of keel-flowered Fabales,
or vice-versa, could be addressed using the approaches
we present here and a more inclusive phylogeny. Better
understanding of the pollination biology of keeled and
non-keeled genera of both Fabaceae and Polygalaceae
would also be informative. In the field, research to better
understand the pollination biology could include inves-
tigations to determine whether (1) there is any inter-
specific facilitation or competition (or both) between
co-existing keel flowers [53]; (2) there are phenological
differences or pollinator choice differences among co-
existing keel flowers [53, 55, 78, 79]; (3) detailed measure-
ments of floral parts (e.g., keel/flag length, colour, minor
floral shape differences) are suggestive of shared pollina-
tion niche [75]; (4) there are shared main and secondary
pollinators; (5) there are different body positions of the
pollinators during pollen removal and pollination; (6)
Page 9 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
there is any evidence of adaptation of mechanical parts
of the flowers [75]; (7) population sizes and plant densi-
ties of the keel flowers effect pollination success [75]; (8)
rewards are [54] offered by sympatric keel-flowered spe-
cies and (9) whether keel-flowered species share odours.
On the other hand, future studies should also focus on
the nectar-free Fabales keel flowers, particularly whether
these species have more colorful and showy flowers, dif-
ferent odor emissions, high specialization rates, lower
levels of pollination and/or pollination with mostly naïve
bees, smaller geographical ranges and whether these
taxa might have undergone a more rapid and extensive
radiation compared to others, as in the case of orchids
([76]; Anonymous Reviewer 2, pers. comm.). Ultimately
however, even if the pollination biology of extant spe-
cies was suggestive of mimicry and a phylogenetic study
supported it, an ancient mimicry scenario cannot be as
robustly tested as a contemporary mimicry.
Methods
Taxon sampling andsequence data
Our phylogeny was reconstructed using published matK,
rbcL and trnL plastid gene regions for 678 taxa, with 43
Fabidae outgroups. We reconstructed our phylogeny
from the most widely available sequence data for all fami-
lies of the Fabales. Whilst recent studies have employed
considerable more sequence data (e.g., [8082]), these
data are not presently available across the Fabales. e
monophylly of Fabales has been strongly supported;
yet, both the fossil record and molecular studies (e.g.,
[12, 17, 48, 49]) suggest a rapid radiation for the order,
which causes unstable phylogenetic relationships among
the four families, namely, change in the topology and the
root of the order by the choice of genes, outgroups and
phylogenetic methods. Similarly, the evolutionary origin
of the six subfamilies of Fabaceae has been reported as
near simultaneous [81]. While the current study exceeds
the taxon sampling of Bello etal. [12, 17], Aygoren Uluer
etal. [49] and Koenen etal. [81, 82], it is the same as
Aygoren Uluer etal. [48]; however, none of these stud-
ies were able to support a robust topology for the order.
Furthermore, Koenen etal.s [81] recently published phy-
logeny of the early evolving Leguminosae based on 1103
nuclear orthologues included only two Polygalaceae
and one Surianaceae taxa, and therefore, it would not
be possible to explore our molecular dating and ances-
tral reconstructions on their trees. Yet, it is encouraging
that the previous attempts, particularly Koenen et al.’s
[81] reconstructions in earliest evolving Papillionoideae
are congruent to the current one. Furthermore, while we
acknowledge that more data might indeed yield a higher
resolution and support in the future; however, we believe
that by using sets of Bayesian trees, we did not introduce
spurious accuracy where data are not decisive.
e dataset contained the matK, trnL and rbcL plastid
gene regions for 678 taxa (615 Fabaceae, 14 Polygalaceae,
five Surianaceae and the sole genus of Quillajaceae, Quil-
laja). e GenBank numbers for these taxa are provided
in (Appendix 1). Our sampling strategy was designed to
include one species from each Fabales genera and Fabi-
dae families as outgroups (43 outgroup taxa from Cel-
astrales, Cucurbitales, Fagales, Malpighiales, Oxalidales,
Rosales, Zygophyllales). Our sampling corresponds to
80% of Fabaceae genera (3% of species number) and 70%
of Polygalaceae genera (1.4% of species number).
Alignment, phylogenetic analyses
We assembled, trimmed, and aligned the sequences by
using Geneious Pro 4.8.4 [83]. All indels were treated as
missing data in all analyses.
e data matrix consisted of 3894 characters from 43
outgroup and 635 ingroup taxa, and 2445 (63%) charac-
ters were variable. Of these, 477 (12%) characters were
parsimony uninformative, while 1968 (51%) characters
were parsimony informative.
Maximum likelihood (ML) analyses were performed
with RAxML [84], under a gamma model of heterogene-
ity with 1000 bootstrap replicates and with defined out-
group taxa and partitions for each data set and gene.
Model choice andmolecular dating analyses
For divergence time estimates we used BEAST v.1.8.0
[85]. e alignment was imported in BEAUti v.1.8.0 to
[86] generate BEAST input files. BEAST was allowed to
perform 2 × 107.
MCMC generations, sampling every 1000th genera-
tion. We used a Yule process with a randomly generated
starting tree and a lognormal relaxed model (uncorre-
lated) [87]. By using jModelTest2.1.10 [88, 89], for each
of the genes, the most appropriate model was selected as
GTR+G+I. Our study uses 30 fossil (24 ingroup and 6
outgroup) calibrations (Table2). Other than the two rela-
tively recent fossils, these fossil calibrations were taken
from Lavin, Herendeen & Wojciechowski [90], Bruneau
etal. [91] and Simon et al. [92]. Furthermore, six out-
group fossils were adopted for the first time in the con-
text of a Fabales phylogeny.
e two new fossils used in this study are: (1) fos-
sil leaves and fruits of Cercis from Oregon, USA
with ~ 36 Ma age [93] (calibration point C). We did not
perefer to use the 34Ma old Cercis fossil [106] which was
used by Lavin, Herendeen & Wojciechowski [90], Bru-
neau etal. [91] and Simon etal. [92], instead we used this
recently described fossil in the current study because it
represents the oldest fossil record of Cercis (Herendeen,
Page 10 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
pers. comm.). e 34Ma old Cercis fossil was attributed
to C. herbmeyeri Jia & Manchester, based on the “pres-
ence of indehiscent pods with a wing like flange along
one margin” [106]. e fossil specimen was collected by
S. R. Manchester and students from Teater Road, Crook
County, Oregon in the 1980s, and was dated radiomet-
rically to ~ 36 Ma with the help of an age for a nearby
location, namely White Ash of Post tuff [106]. (2) fos-
sil seeds of Newtonia from Ethiopia [114]. is earliest
fossil record for the genus dates to 22–21Ma, and used
in the current study for the calibration point C (Her-
endeen, pers. comm.). A fossil of Newtonia mushensis
Pan, Currano, Jacobs, Feseha, Tabor et Herendeen is the
earliest and only definitive Newtonia fossil, was collected
from e Mush Valley deposits, and dated by U-Pb radi-
oisotope dating Method [114]. is new taxon is distin-
guished by seed size and seed characteristics (e.g., “flat,
elongate tapering seeds bearing a membranous wing
the degree of curvature near the funiculus attachment”)
[114]. We also preferred to include Lavin, Herendeen &
Wojciechowski’s [90] 60–70Ma legume stem node con-
straint to the molecular clock rooting analysis (i.e., uni-
form prior distribution) for two reasons: (1) Lyson etal.
[121] indicated that the Fabaceae oldest fossil record
Table 2 Fossils used to calibrate the Fabales tree
Sources for the calibration points are provided in the table. Outgroup fossils were adopted from Magallón etal. [116]
Mrca most recent common ancestor, Ma million years ago
Name Node constrained Fossil organ(s) Geographic location Age (Ma) References
A Fabaceae stem node Early fossil record of Fabaceae Various locations 60–70 [90, 92]
CCercis stem node Cercis leaves and fruits Western North America 36 [93]
DBauhinia stem node Bauhinia s.l. leaves Tanzania 46 [91, 94, 92]
EHymenaea stem node Hymenaea flower Dominican Republic 24 [9092, 92]
F Mrca of Prioria and Oxystigma Prioria flowers Dominican Republic 24 [91, 96, 92]
F2 Mrca of clade of Dimorphandra group Protomimosoidea buchanensis flowers Tennessee, USA 55 [9092, 90, 92]
GDaniellia stem node Daniellia wood France 53 [91, 99, 92]
HAphanocalyx stem node Aphanocalyx leaves Tanzania 46 [91, 100, 92]
ICrudia stem node Crudia fruits and leaflets SE USA 45 [91, 101, 92]
I2 Stem node leading to Styphnolobium
and Cladrastis
Styphnolobium and Cladrastis fruits
and leaves Tennessee, USA 40 [102, 90, 92]
J Papilionoideae stem node Barnebyanthus buchananensis flowers SE USA and Wyoming, USA 55 [9092, 90, 92]
J2 Genistoid crown node Leaves and pods similar to Bowdichia
and Diplotropis
Western Wyoming, USA 56 [105, 90, 92]
KSwartzia stem node Swartzia fruits and leaflets SE USA 45 [91, 102, 92]
K2 Machaerium stem node Leaflets Northern Mississippi, USA 40 [102, 90, 92]
LArcoa stem node Prosopis linearifolia leaves Florissant Locality, USA 34 [9092, 92]
L2 Mrca of Tipuana and Maraniona Tipuana fruits Southern Ecuador 10 [107, 90, 92]
M Mrca of Acrocarpus Acrocarpus fruit SE USA 45 [91, 92]
M2 Robinia stem node Robinia zirkelii wood North America and Europe 34 [108, 90, 92]
NSenna stem node Senna fruits SE USA and Mexico 45 [91, 109, 102, 92]
OCaesalpinia stem node Mezoneuron fruits SE and W USA 45 [9092, 92]
Q Mrca of Acacieae/Ingeae Ingeae/Acacieae fossil pollen Egypt 45 [91, 111, 92]
RDinizia stem node Eumimosoidea plumosa flowers,
leaves and fruits SE USA 45 [91, 112, 101, 92]
XCalliandra stem node Calliandra pollen Argentina 16 [113, 92]
YNewtonia stem node Newtonia seeds Ethiopia 21 [114]
124 Cucurbitaceae stem node Cucurbitospermum sheppeyense seeds London, UK 48.6 [115, 116]
117 Fagales stem node Archaefagacea futabensis flowers and
fruits North-eastern Honshu, Japan 87.5 [116, 117]
121 Juglandaceae plus Myricaceae stem
node Caryanthus flowers and fruits Georgia, USA 83.5 [116, 118]
123 Betulaceae stem node Bedellia pusilla flowers Georgia, USA 83.5 [116, 118]
113 Rhamnaceae stem node Coahuilanthus belindae flowers Coahuila, Mexico 70.6 [119, 116]
115 Ulmaceae stem node Ulmites leaves Northern Hemisphere sediments 55.8 [116, 120]
Page 11 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
corresponds to 65.35Ma, and this age is within the range
we used to constrain the 60–70Ma legume stem node,
and (2) any convincing Fabaceae fossils prior to ca. 58Ma
are lacking [59, 90, 92, 101, 122]. To accommodate for
gaps in the fossil record and uncertainity in fossil age
estimates [105, 123], other than the 60–70Ma legume
stem node constraint [90], we used lognormal prior dis-
tribution with minimum age constraints. No fossils from
Polygalaceae (e.g., [124127]) and Surianaceae (e.g., [128,
129]) were used due to their unconfirmed status [12, 39,
90].
All BEAST analyses were implemented online via the
CIPRES Portal [130]. Two independent runs were com-
bined using LogCombiner v.1.8.0 [131]. Tracer v.1.6 [132]
was used to check for proper mixing and convergence.
TreeAnnotator v1.8.0 [133] was used to elect the maxi-
mum clade credibility trees. To annotate the tree, Inter-
active Tree of Life (iTOL) [134] was used.
Ancestral area reconstruction
Eight biogeographic regions were defined according to
Buerki etal. [47], with one addition. ese areas were:
A: Eurasia; B: Africa; C: Madagascar; D: Southeast Asia
including Pacific Islands; E: Australia including New
Guinea, New Caledonia and New Zealand; F: North
America; G: South America including Central America
and H: the Indian subcontinent. Here, area H includes
India, Pakistan, Sri Lanka and Bangladesh, but not Nepal.
e Indian subcontinent was treated as a separate area
(H) in this study due to its recent (ca. 55Ma) collision
with the Eurasian plate [135]. e crown age of Fabales
was estimated to be 84 Ma (maximum) by Bello et al.
[12]. erefore, taking the Indian subcontinent as a sepa-
rate geographic area would be appropriate.
Geographic information for legume taxa was obtained
from Legumes of the World [14]. For non-legume taxa,
biogeographic information was obtained from published
sources. Geography was scored at generic level for both
legume and non-legume taxa, rather than for the spe-
cies that were actually sampled. However, for the purpose
of consistency, some clarifications are needed. First, the
regions or countries covering more than one of the geo-
graphic regions were coded as: Mexico: F+G; Himalayas:
A+H; Pakistan: A+H; pantropical, tropics or circum-
tropical: all areas from A to H; neotropical: F+G; paleo-
tropical: A+B+C+D+E+H; subtropics: A+B+E+F+G;
Southeast Asia: A+D; Asia: A+D+H. Second, when lit-
erature referred to a centre of diversity, this was taken as
the distribution area. For instance, for a genus with a cen-
tre of diversity containing 30 spp. in North America, and
one species with pantropical distribution, North America
was accepted as the distribution area.
Biogeographical analyses were performed on our
Bayesian tree with 678 taxa. e Lagrange (Dispersal-
Extinction-Cladogenesis, DEC model; [136, 137]) option
of RASP v.4.2 (Reconstruct Ancestral State in Phylog-
enies; [138]), was employed with default settings to cal-
culate probabilities of the most likely ancestral areas for
each clade (Additional file3: S3), except the “maximum
number of areas” option, which was set to 2 (the mini-
mum), 4 and 6 to compare the results. A larger value (8,
the maximum number of areas) was not tested; we speci-
fied the maximum number of areas as 4 since varying
numbers of areas only slightly modified probabilities. e
notable changes were for Fabaceae: the ancestral origin
was 52% G or 49% BG if the maximum number of areas
was set to 2, but 67–74% B+G or 33–26% G if the maxi-
mum number of areas was set to 4 and 6.
We applied a stratified biogeographical model by
dividing our model into four time slices: before 80Ma,
between 80 and 65 Ma, between 65 and 30 Ma, and
30Ma to the present day [47]. We also applied Buerki
et al.s [47] Q matrix in our ancestral area analysis, in
which transition rates were dependent on the geographic
location of areas.
Ancestral trait reconstructions
Aygoren Uluer’s [70] review shows that the actual pollina-
tors (rather than visitors) are known for only 33 keel flow-
ered species of Fabales. e present study uses trait data
from literature review of hundreds of published papers,
and all available Floras score the traits that can be used to
infer pollination syndrome. Many floral traits contribute
to pollinator attraction. ese include flower type, flo-
ral (corolla) symmetry, fusion of floral parts, flower size,
length of nectar tube, inflorescence size, number of flow-
ers in an inflorescence, inflorescence type, flower colour,
floral reflectance, habit, height, height of flowers from
ground, phenology, and floral scent [22, 28, 56, 139145].
Having a bilateral symmetry, a pentamerous corolla with
three different petal types, with the reproductive organs
enclosed by keel petals and generally with connation of
floral parts such as stamens and keel petals are also the
essential characters of keel flowers [110]. In the cur-
rent study, eleven morphological traits were selected as
potentially the most important from the point of view of
a pollinator (explained in detail below) and traced: floral
type (keeled or not), presence or absence of a pentamer-
ous corolla (petals+sepals in Polygalaceae), presence or
absence of three distinct petal types (petals+sepals in
Polygalaceae), presence or absence of enclosed repro-
ductive organs, floral symmetry, androecium type, inflo-
rescence type, inflorescence size, flower size, height and
habit (Table3).
Page 12 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
Table 3 Explanation of eight pollination syndrome characters coded as A, B and/or C
Character Character state
Inflorescence type A = Sequenced inflorescences (i.e.,
vertical inflorescences): raceme,
panicle, spike, thyrse
B = Cluster type inflorescences (i.e., horizontal inflorescences): umbel, cyme,
corymb, head, spike, fascicle C = Solitary flowers
Habit type A = Tall plants: tree, climber, liana,
vine, scrambler B = Medium plants: shrub, subshrub C = Small plants: herb
Androecium type A = Free stamens B = Fused stamens C = Polymorphic
Presence or absence of three types of
petals (or petals+sepals in Polygal-
aceae),
A = YES B = NO C = The presence or absence of only
two types of petals (or petals+sepals in
Polygalaceae)
Presence or absence of a pen-
tamerous corolla (pentamerous
petals+sepals in Polygalaceae)
A = YES B = NO
Presence or absence of enclosed
reproductive organs A = YES B = NO
Presence or absence of a bilateral
symmetry A = Radial symmetry (including
slightly bilateral symmetry) B = Bilateral symmetr y
Keeled or not keeled A = Keeled B = Non-keeled
Page 13 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
1.a. e first character scored flowers as keeled or not
keeled (Table3, Additional file4: S4). For this ancestral
floral type analyses, we coded two states: A = keeled and
B = non-keeled. In this case, Bello etal. [1] did not accept
Xanthophyllum Roxb. flowers as keeled, but Van der
Meijden [50] reported that some Xanthophyllum species
may have keel flowers. On the other hand, Breteler and
Smissaert-Houwing [146] reported that both Carpolo-
bia G. Don and Atroxima Stapf have a keel petal which
encloses the style and the stamen sheath similar to the
Papilionoideae keel flowers. Unlike Van der Meijden [50],
these authors avoided using the term papilionate flow-
ers. erefore, following Bello etal. [1], we did not accept
Carpolobia and Atroxima as keel-flowered. In contrast,
we coded Xanthophyllum as polymorphic for the charac-
ter of being keel flowered or not.
e keel flower trait is known a priori to have more
than one origin, and the purpose of our analyses are to
highlight the recurring origin of the trait in a much more
transparent and explicit way. We note however that non-
keel flowers within Papilionoideae are not homologous,
and referring to all of them as non-keeled may mislead
analyses seeking to understand the transitions to keel
morphologies [4]. With this in mind, we also divided the
keel-flower trait into five further sub-traits which are:
presence or absence of a pentamerous corolla (pentamer-
ous petals+sepals in Polygalaceae), presence or absence
of three types of petals (or petals+sepals in Polygalaceae),
presence or absence of enclosed reproductive organs,
presence or absence of a bilateral symmetry and androe-
cium type [7, 9, 147] (Table3, Additional files 5: S5, 6: S6,
7: S7, 8: S8, 9: S9).
1.b. For the presence or absence of a pentamerous
corolla (pentamerous petals+sepals in Polygalaceae)
analyses, we coded two states: A = YES and B = NO
(Table3).
1.c. For the presence or absence of three types of pet-
als (or petals+sepals in Polygalaceae), analyses, we coded
three states: A = YES, B = NO and C = the presence or
absence of only two types of petals (or petals+sepals in
Polygalaceae) (Table3).
1.d. For the presence or absence of enclosed reproduc-
tive organs analyses, we coded two states: A = YES and
B = NO (Table3).
1.e. For the floral symmetry analyses, we coded two
states: A = radial symmetry (including slightly bilateral
symmetry) and B = bilateral symmetry (Table3).
1.f. For the androecium type analyses, we coded
three states: A = free stamens, B = fused stamens and
C = polymorphic (Table3). In this case, if the stamens
are united at the base, we accepted this as free, due to
a possible visual impact for pollinators. Although we
code fusion of the androecium, we think that fusion of
the petals is particularly common among later-diverg-
ing Papilionoideae tribes [6, 7, 9, 147]. erefore, we
did not include this character to our ancestral state
analyses.
2. Inflorescence architecture is another important fac-
tor that affects pollinator visitation [56, 140, 148]. For
example, two-dimensional inflorescences receive more
hummingbird visits than three-dimensional ones [149].
Likewise, for vertical inflorescences, such as racemes,
pollinators generally move from the bottom upwards (i.e.,
from oldest to youngest flowers) and starts to forage at
the next inflorescence in this exact way [148, 150, 151].
However, it is not possible to find the same pattern on
horizontal inflorescences such as umbels or heads. For
these reasons, it is possible that for a pollinator, the vis-
ual impact of the inflorescence may be more important
than the type of inflorescence, with convergent evolu-
tion on function between different inflorescence types.
In other words, there might not be much visual differ-
ence between a panicle and a raceme in terms of what
a bee sees. For these reasons, inflorescence morphology
was coded as: A = Sequenced inflorescences (i.e., verti-
cal inflorescences): raceme, panicle, spike and thyrse;
B = Cluster type inflorescences (i.e., horizontal inflores-
cences): umbel, cyme, corymb, head, spike and fascicle;
C = Solitary flowers (Table 3, Additional file 10: S10).
It might have been informative to break this character
down to overall shape of inflorescence, perhaps as width
to length ratio, but this information was not available for
all taxa.
3. Similarly, by effecting the foraging time of bees, not
only the number of flowers in an inflorescence [152], but
also the inflorescence size [140, 153] are other impor-
tant criteria for pollinator attraction. While we could not
obtain sufficient information about the number of flow-
ers per inflorescence, we traced ancestral inflorescence
sizes of first keel-flowered lineages of both Fabaceae and
Polygalaceae. Both floral size and inflorescence size were
scored in millimetres, and we considered both the small-
est and the largest reported sizes for all taxa (Additional
files 11: S11 and 12: S12, respectively).
4. Flower size is frequently reported to be an important
part of pollinator attraction and therefore pollinator visi-
tation [40, 145, 154156]. e correlation between flower
size and pollinator size (e.g., [157]), flower size and polli-
nator visitation rate (e.g., [158]), flower size and searching
time (e.g., [145]) were shown by several studies; however,
the results are almost always case dependent. Further-
more, while Fabaceae contains great diversity in flower
size, from species with tiny flowers only a few millime-
tres in length (e.g. Trifolium L.) to giants (e.g., Erythrina
L.), in Polygalaceae small flowers predominate. ere-
fore, we find it necessary to investigate ancestral floral
Page 14 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
sizes of first keel-flowered lineages of both Fabaceae and
Polygalaceae.
5. Since pollinators tend to forage at constant heights
to decrease flight distances [159162], another important
criterion for the study was height of plants and inflores-
cences from ground. However, since it is not always pos-
sible to find information about the inflorescence height
from ground, approximations were made based on habit
and height of plants, since both are frequently reported
in the literature. We coded height of plants in centime-
tres, and we considered both the smallest and the largest
reported sizes for all taxa (Additional files 13: S13 and 14:
S14, respectively).
6. For the habit analyses, we coded three states: A = Tall
plants: Tree, climber, liana, vine, scrambler; B = Medium
plants: shrub, subshrub; C = Small plants: herb (Table3,
Additional file1: S15).
Unfortunately, some traits could not be included in the
current study due to the scarcity of information. ese
included UV reflectance (e.g., FReD: the floral reflectance
database, [166]), presence or absence of pollen, presence
or absence of secondary pollen presentation, presence or
absence of nectar, length of nectar tube, height of flowers
from ground and number of flowers in an inflorescence.
Tracing others, such as phenology and floral colour was
not possible due since we scored traits at generic level.
Mapping global phenological data of a legume genus
resulted a year-long flowering season for that taxon. Sim-
ilarly, tracing the colour trait resulted as “all colours” for a
genus, due to the occurrence of many differently coloured
flowers of a large genus around the world. e 11 charac-
ters were scored for 635 taxa (excluding outgroups) in the
four Fabales families. Data for these morphological traits
were gathered from hundreds of appropriate, previously
published sources including floras, articles and online
sources (Additional file1: S16). Our data are presented
in the same linear order as the phylogenetic classification
of Lewis [14], Gagnon etal. [163] and LPWG [15]. For all
analyses, missing data were coded as "-".
In our analyses, we did not score geography and mor-
phology at the species level, because our aim was to
reflect the diversity within each genus, not each species.
For example, while the flower size ranges from 3mm to
2.5 cm in genus Polygala (e.g., P. triflora vs. P. karen-
sium), in terms of pollination, scoring Polygala flowers as
3mm or 25mm would not be meaningful. e same logic
applies here for at least floral type, habit, height, inflores-
cence size and inflorescence type analyses. erefore, we
think that scoring both the geography and morphology at
the genus level is more appropriate in our situation.
Excluding outgroups which were scored as missing
data, the amount of missing data for the flower type and
ancestral area analyses was 0%, 0.5% for the presence or
absence of three distinct petal types (petals+sepals in
Polygalaceae) analysis, 2.8% for the presence or absence
of enclosed reproductive organs analysis, 1.1% for the
floral symmetry analysis, 8.7% for the androecium type
analysis, 3.78% for the presence or absence of a pentam-
erous corolla (petals+sepals in Polygalaceae) analysis,
2.99% for the inflorescence type analysis, 15.9% for both
the smallest and the largest flower size analyses, 16.38%
for the smallest height analysis, 7.87% for the largest
height analysis and 1.4% for the habit analysis. Unfortu-
nately, the amount of missing data for both the smallest
(46.6%) and the largest (42.2%) inflorescence size analy-
ses was very high, due to the scarcity of information. For
this reason, we could not estimate ancestral inflorescence
sizes for most of the clades and ultimately we excluded
ancestral inflorescence size analyses from our study.
To account for phylogenetic uncertainty, ancestral state
reconstructions were performed on a sample of boot-
strap trees with branch lengths. Since the phylogenetic
relationships of the early-branching Papilionoideae are
better resolved in our ML tree(s), we preferred to use
the population of ML trees over our Bayesian tree. e
program BayesTraits v2.0 [164, 165] was used for Bayes-
ian estimation of ancestral states. For the “MultiState”
model, MCMC analyses were run for 2 × 106 genera-
tions, with default settings except the ratedev (rate devia-
tion) and rjhp exp (RevJump) parameters and burn-in
(the first 200,000 iterations). e “Continuous Random
Walk” analyses were run with default settings, except the
ratedev parameter. For the flower type analysis, we also
conducted additional MCMC analyses for several Papil-
ionoideae nodes in order to pinpoint the origin of keel
flowers within the subfamily.
Appendix1
Taxon sampling for the phylogenetic analyses of order
Fabales based on the plastid rbcL, matK and trnL. A dash
indicates the region was not sampled. GenBank acces-
sion numbers are presented in the following order: rbcL,
matK, trnL.
FABACEAE. Subfamily Duparquetioideae: Duparque-
tia —, EU361937.1, EU361800.1. Subfamily Dialioideae:
Poeppigia AY904370.1, AY386907.1, EU361829.1. Bau-
douinia —, EU361871.1, KJ620940.1. Eligmocarpus —,
EU361939.1, EU361801.1. Mendoravia —, EU362001.1,
EU361823.1. Distemonanthus —, EU361936.1,
AF365084.1. Apuleia U74249.1, EU361858.1,
EU361737.1. Storckiella AM234249.1, GU321970.1,
AF365078.1. Labichea —, EU361989.1, AF365076.1. Pet-
alostylis AF308719.1, AY386895.1, KJ620947.1. Koom-
passia —, EU361988.1, EU361816.1. Martiodendron —,
EU361999.1, KJ620942.1. Zenia AF308722.1,
Page 15 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
EU362065.1, KJ620951.1. Dialium AM234245.1,
EU361930.1, KJ620960.1. Dicorynia JQ626129.1,
EU361931.1, KU356727.1. Subfamily Cercidoideae: Cer-
cis U74188.1, KT461986.1, FJ801163.1. Adenolobus
AM234264.1, EU361845.1, FJ801158.1. Grionia
AM234265.1, JN881419.1, FJ801165.1. Brenierea
AM234269.1, JN881409.1, —. Bauhinia KX119265.1,
AY386893.1, MF135595.1. Gigasiphon JF738566.1,
JN881416.1, FJ801108.1. Tylosema AJ584710.1,
JN881457.1, FJ801124.1. Barklya —, JN881354.1,
FJ801076.1. Lysiphyllum —, JN881430.1, FJ801152.1.
Phanera —, JN881450.1, FJ801144.1. Lasiobema —,
EU361873.1, FJ801138.1. Piliostigma JF265551.1,
JN881454.1, —. Subfamily Papilionoideae: Bobgunnia
AM234258.1, EU361885.1, AF365038.1. Swartzia
AM234259.1, EU362053.1, KU728673.1. Candolleoden-
dron —, JX295890.1, EF466264.1. Trischidium —,
JX295868.1, JX275898.1. Cyathostegia —, AY553713.1,
EF466267.1. Ateleia U74201.1, JX295883.1, EF466259.1.
Amburana —, KX816341.1, EF466254.1. Mildbraedio-
dendron —, —, AF309847.1. Cordyla U74204.1,
JX295923.1, AF309848.1. Aldina U74252.1, KP177924.1,
JX275891.1. Zollernia —, JX152595.1, JX275945.1. Holo-
calyx U74244.1, JX152593.1, JX187644.1. Lecointea
AM234260.1, EU361990.1, JX187645.1. Harleyodendron
—, JX152592.1, JX187643.1. Exostyles —, JX152590.1,
JX187641.1. Baphiopsis —, JX295895.1, JX570586.1.
Alexa JQ625719.1, JQ669613.1, KC178829.1. Castano-
spermum U74202.1, JX295891.1, AF311375.1. Angyloca-
lyx U74200.1, JQ669611.1, AF311366.1. Xanthocercis
U74189.1, JF270996.1, AF311365.1. Dussia U74206.1,
JX295925.1, KC178835.1. Myrocarpus —, JF491270.1,
JX275895.1. Myroxylon U74208.1, JX295912.1,
JX275949.1. Myrospermum U74207.1, AY386959.1,
AF309851.1. Cladrastis U74232.1, AY386861.1,
AF311370.1. Styphnolobium KY872756.1, AY386962.1,
KY872756.1. Calia —, AY386864.1, AF311374.1. Uribea
—, AY553719.1, AF311000.1. Sweetia —, JX152620.1,
JX187673.1. Luetzelburgia U74185.1, KX816379.1,
JX187701.1. Ormosia JQ626235.1, KY079031.1,
JX275921.1. Pericopsis U74210.1, —, —. Acosmium
U74255.1, JX124417.1, JX124467.1. Bowdichia
MG718274.1, JX124395.1, AF309486.1. Diplotropis
JQ625878.1, JX124418.1, KC178836.1. Clathotropis —,
KX584410.1, JX275957.1. Bolusanthus U74243.1,
AF142685.1, AF310994.1. Platycelyphium —, —,
AF309864.1. Dicraeopetalum —, GQ246142.1,
JX275958.1. Cadia U74192.1, JX295932.1, AF309863.1.
Ammodendron —, AY386957.1, —. Maackia AB127042.1,
AY386944.1, MF444206.1. Sophora U74230.1,
AF142693.1, JF338266.1. Salweenia U74251.1, —, —.
Camoensia —, JX295919.1, KC178831.1. Dalhousiea —,
—, AF310998.1. Airyantha —, JX295897.1, AF310997.1.
Leucomphalos —, JX295864.1, KU324664.1. Baphia
AM234261.1, EU361866.1, JX570590.1. Amphimas —,
JX295894.1, KU324665.1. Panurea —, JX295947.1,
JX275951.1. Spirotropis —, JX295950.1, KC178832.1.
Taralea —, KX595211.1, JX275948.1. Pterodon —,
AH009912.2, AF208895.1. Monopteryx —, JX295876.1,
JX275906.1. Dipteryx JQ625725.1, JX295869.1,
JX275899.1. Cyclolobium —, KJ028452.1, KX652197.1.
Poecilanthe AB045818.1, KJ028459.1, KX652211.1. Har-
palyce —, AF142689.1, —. Brongniartia U74253.1,
GQ246147.1, —. Plagiocarpus —, GQ246160.1, —. Tem-
pletonia —, GQ246158.1, AF518122.1. Hovea Z95537.1,
AY386889.1, AF518123.1. Lamprolobium —,
GQ246159.1, —. Euchresta AB127040.1, —, AB127032.1.
Pickeringia —, AY386863.1, —. Ammopiptanthus —,
JQ820167.1, —. Anagyris Z70122.1, —, FJ499419.1. Coch-
liasanthus KF621120.1, —, KF621109.1. Piptanthus
Z70123.1, AY386924.1, KP636629.1. Thermopsis
JX848468.1, AY386866.1, HM590355.1. Baptisia
Z70120.1, AY386900.1, FJ499421.1. Cyclopia
AM261716.1, JX518243.1, —. Xiphotheca AM260746.1,
—, —. Amphithalea AM235004.1, —, —. Stirtonanthus
AM259368.1, —, —. Podalyria U74217.1, JX518039.1, —.
Liparia AM259362.1, JX517632.1, —. Virgilia
AM260739.1, JX517500.1, AF518125.1. Calpurnia
U74239.1, AY386951.1, AF310993.1. Spartidium
EU347931.1, —, —. Lebeckia EU347924.1, GQ246144.1,
—. Wiborgia EU347975.1, —, —. Rafnia EU347896.1,
JQ412281.1, —. Aspalathus EU348020.1, JQ412203.1, —.
Lotononis Z95538.1, —, —. Bolusia EU347942.1,
JQ040984.1, —. Crotalaria EU348034.1, AY386867.1,
KP691152.1. Pearsonia EU347950.1, —, —. Rothia
EU347953.1, —, —. Robynsiophyton EU347952.1, —, —.
Melolobium Z95540.1, —, —. Dichilus EU347959.1,
GQ246143.1, —. Polhillia EU347958.1, —, —. Argyrolo-
bium Z95549.1, JQ412199.1, EU341594.1. Lupinus
Z70070.1, AY386943.1, KX147711.1. Anarthrophyllum
—, AY386923.1, AY618488.1. Adenocarpus Z95545.1,
JQ858229.1, —. Cytisophyllum Z70090.1, —, AJ890966.1.
Argyrocytisus Z70092.1, —, AJ890961.1. Petteria
Z70091.1, —, AJ891026.1. Laburnum KM360837.1,
HE967423.1, DQ417004.1. Cytisus HM849943.1,
AY386902.1, MH000081.1. Calycotome —, —,
JF338229.1. Echinospartum —, —, AF385415.1. Erinacea
Z70105.1, —, AJ891029.1. Retama Z70117.1, —,
AJ304872.1. Genista KM360800.1, AY386862.1,
JF338287.1. Spartium HM850377.1, AY386901.1,
JF338264.1. Stauracanthus —, —, AF385416.1. Ulex
HM850431.1, JQ669586.1, AF385419.1. Apoplanesia —,
AF270860.1, AF208898.1. Parryella —, AY391812.1, —.
Amorpha U74212.1, KP126864.1, AF208899.1. Errazuri-
zia —, AY391803.1, —. Eysenhardtia —, AY391807.1, —.
Psorothamnus —, AY391818.1, —. Marina —,
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Ulueretal. BMC Ecology and Evolution (2022) 22:45
AY391811.1, —. Dalea —, AY391801.1, —. Vatairea
AB045826.1, JX152606.1, JX187664.1. Vataireopsis
JQ626110.1, AF142680.1, JX187670.1. Hymenolobium
JQ625919.1, JX295903.1, JX275939.1. Andira U74199.1,
JF501102.1, JX275929.1. Adesmia U74254.1, JN835371.1,
—. Amicia —, AF203583.1, KF477933.1. Zornia U74235.1,
KX595215.1, KF477982.1. Poiretia —, KX703011.1, —.
Nissolia —, EU025907.1, AF208908.1. Chaetocalyx —,
AF203585.1, KF477943.1. Riedeliella —, AH009910.1,
MH603439.1. Discolobium —, AF270873.1, AF208964.1.
Cranocarpus AB045796.1, AF270875.1, AF208951.1. Brya
—, AF270876.1, AF208950.1. Platymiscium JQ626063.1,
EU735957.1, EU736043.1. Platypodium GQ981836.1,
AF270877.1, AF208961.1. Inocarpus JN083773.1,
AF270878.1, AF208965.1. Maraniona KF436463.1,
KF436439.1, —. Tipuana KF436476.1, AF270882.1,
AF208956.1. Ramorinoa JN083776.1, AF270881.1,
AF208957.1. Centrolobium JN083771.1, EU401414.1,
EU401427.1. Paramachaerium KF436467.1, AF272062.1,
AF208959.1. Etaballia KF436461.1, AH009902.1,
AF208960.1. Pterocarpus MK026163.1, AF142691.1,
AF208953.1. Cascaronia —, AF272072.1, AF208958.1.
Georoea —, AF270880.1, AF208962.1. Fissicalyx —,
AF272063.1, AF208938.1. Fiebrigiella —, AF203590.1, —.
Chapmannia —, AF203593.1, AF208941.1. Stylosanthes
JQ592043.1, NC_039161.1, KR737609.1. Arachis
U74247.1, KX595195.1, JN617184.1. Grazielodendron
JN083772.1, AF270862.1, AF208952.1. Dalbergia
U74236.1, AF203582.1, KX268174.1. Machaerium
U74248.1, KX898288.1, EF451120.1. Aeschynomene
AF308701.1, AH009907.2, AF208927.1. Cyclocarpa —,
AF272067.1, —. Soemmeringia —, AH009909.1,
AF208937.1. Smithia —, AF272066.1, AF208933.1.
Kotschya —, AF272065.1, KC560761.1. Humularia —,
AF272069.1, AF208936.1. Bryaspis —, AF272068.1,
AF208932.1. Geissaspis JQ933342.1, AF272064.1,
AF208931.1. Pictetia —, AF203579.1, GQ889095.1.
Diphysa JQ591721.1, AF203574.1, AF260645.1. Ormocar-
pum JX572809.1, AF203602.1, AF260646.1. Ormocar-
popsis —, AF203567.1, AF208918.1. Peltiera —,
GU951672.1, —. Weberbauerella —, AH009903.1,
AF208909.1. Hypocalyptus AF308710.1, AY386886.1,
AF518126.1. Gompholobium —, AY386891.1,
AF518129.1. Sphaerolobium —, —, AF518136.1. Davie-
sia AF308708.1, AY386887.1, KY426137.1. Erichsenia —,
—, AF518133.1. Viminaria —, —, AF518134.1. Isotropis
AF308712.1, —, AY015083.1. Jacksonia —, AF298481.1,
AF518147.1. Leptosema —, —, AF518148.1. Latrobea —,
AF298484.1, AY883186.1. Euchilopsis —, —, AF113779.1.
Phyllota —, AF298509.1, AF113785.1. Aotus —,
AY386884.1, AY883181.1. Urodon —, —, AF113792.1.
Stonesiella —, —, AF113791.1. Almaleea —, —,
AF113775.1. Eutaxia —, —, AF113789.1. Dillwynia —, —,
AF113778.1. Pultenaea —, —, AY883260.1. Mirbelia —,
—, AY015087.1. Chorizema U74218.1, —, AF518154.1.
Oxylobium —, —, AF113782.1. Podolobium —, —,
AY015106.1. Callistachys —, AF298433.1, AY015072.1.
Gastrolobium —, —, AY015082.1. Brachysema —, —,
AY015071.1. Nemcia —, —, AY015099.1. Goodia
U74258.1, —, KM876834.1. Platylobium —, —,
KM876825.1. Muelleranthus —, —, KM876759.1. Ptycho-
sema —, —, AF518165.1. Aenictophyton —, —,
AF518144.1. Phylloxylon U74256.1, AY650280.1,
AF274358.1. Cyamopsis —, AF142698.1, AF274359.1.
Indigastrum —, —, AF274364.1. Microcharis —,
AY650279.1, AF274363.1. Rhynchotropis —, —,
AF274361.1. Vaughania —, —, KR738660.1. Indigofera
U74214.1, AF142697.1, KX268190.1. Callerya
AY308806.1, KP230744.1, AF124242.1. Endosamara
AY308805.1, —, —. Afgekia GQ436345.1, —, —. Wisteria
Z95544.1, AF142731.1, AF124239.1. Austrosteenisia
U74242.1, AF142707.1, AF311381.1. Leptoderris
AB045807.1, JX506609.1, —. Dalbergiella AF308724.1,
AF142706.1, —. Aganope AF308702.1, JX506605.1, —.
Ostryocarpus —, JX506599.1, —. Xeroderris AF308727.1,
AF142708.1, —. Fordia AB045802.1, AF142718.1, —.
Dewevrea AB045799.1, —, —. Craibia AB045795.1,
JX517315.1, —. Disynstemon —, GU951670.1, —. Platy-
cyamus AB045817.1, AF142709.1, KT696081.1. Kunstle-
ria —, JX506598.1, —. Craspedolobium KF181485.1,
JF953574.1, —. Philenoptera JF265547.1, JX506606.1,
EU717357.1. Hesperothamnus AB045805.1, —, —. Pis-
cidia AB045816.1, AF142710.1, AF311379.1. Deguelia
AB045798.1, JX506607.1, —. Lonchocarpus AB045809.1,
AF142717.1, AF311382.1. Muellera AB045813.1, —, —.
Derris U74234.1, AF142715.1, AB817670.1. Paraderris —,
JX506654.1, —. Millettia AF308714.1, AF142725.1,
AF311377.1. Pongamiopsis AB045819.1, AF142711.1,
KC479269.1. Chadsia AB045794.1, —, KC479260.1. Mun-
dulea AB045814.1, AF142713.1, AY009136.1. Tephrosia
Z95542.1, EU717429.1, KU750666.1. Apurimacia
AF308703.1, FJ968527.1, —. Ptycholobium —,
JQ669619.1, —. Abrus U74224.1, AF142705.1,
EF543423.1. Dioclea AF308709.1, HQ707540.1, —.
Canavalia AB045793.1, HQ707530.1, EU717354.1.
Galactia AB045803.1, EU717428.1, KJ402390.1. Rhodo-
pis AF308728.1, —, —. Ophrestia EU717289.1,
AF142703.1, EU717359.1. Clitoria EU717286.1,
EU717427.1, EU717355.1. Centrosema AF308706.1,
JQ587552.1, —. Apios KJ773273.1, KF272942.1,
EF543425.1. Shuteria AB045824.1, EU717423.1,
LC228057.1. Mucuna MG946852.1, EU717422.1,
KT696119.1. Kennedia EU717283.1, EU717424.1,
KT696084.1. Hardenbergia EU717284.1, EU717425.1,
EU717332.1. Vandasina —, —, EU717338.1. Spatholobus
AB045825.1, EU106112.1, KF621116.1. Butea
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Ulueretal. BMC Ecology and Evolution (2022) 22:45
AB045789.1, JN008175.1, —. Adenodolichos AF308700.1,
—, —. Paracalyx JQ933431.1, —, —. Bolusafra
EU717272.1, EU717413.1, EU717309.1. Rhynchosia
KF621126.1, JQ587827.1, MG709412.1. Eriosema
KF621122.1, JQ587629.1, KF621111.1. Dunbaria
JQ933314.1, —, —. Cajanus Z95535.1, EU717414.1,
EF200131.1. Flemingia KF621123.1, KF621101.1,
KF621112.1. Erythrina EU717270.1, EU717411.1,
KX268185.1. Psophocarpus AB045820.1, JQ669575.1,
EU717343.1. Otoptera —, JN008176.1, —. Decorsea —,
AY582975.1, —. Strongylodon AF308729.1, —, —.
Calopogonium AF308723.1, JQ669608.1, EU717318.1.
Cologania EU717264.1, EU717405.1, EU717319.1. Pachy-
rhizus KJ468100.1, EU717401.1, EU717324.1. Neonoto-
nia EU717261.1, EU717402.1, EU717323.1.
Neorautanenia AF308715.1, JN008178.1, —. Dumasia
EU717265.1, EU717406.1, EU717320.1. Pueraria
AB045822.1, AY582972.1, LC315108.1. Pseudeminia
AF181936.1, —, —. Pseudovigna EU717262.1,
EU717403.1, EU717325.1. Amphicarpaea (Amphicarpa)
AF181930.1, EU717399.1, LC315110.1. Teramnus
EU717258.1, EU717400.1, LC315106.1. Glycine Z95552.1,
AF142700.1, JN617170.1. Phylacium AB045815.1, —, —.
Wajira —, AY583011.1, —. Sphenostylis —, AY582978.1,
—. Nesphostylis —, AY582979.1, —. Alistilus —,
JN008191.1, —. Dolichos AF413209.1, JN008183.1, —.
Macrotyloma EU717269.1, AY589507.1, EU717341.1.
Dipogon AB045800.1, AY582988.1, —. Lablab
EU717267.1, EU717408.1, EU717339.1. Spathionema —,
AY582990.1, —. Vatovaea —, JN008194.1, —. Phys-
ostigma —, AY582998.1, —. Vigna Z95543.1,
AY582999.1, —. Oxyrhynchus AF308717.1, AY509935.1,
—. Phaseolus KF022496.1, DQ450863.1, —. Ramirezella
—, AY509936.1, EU717344.1. Strophostyles —,
DQ443469.1, EU717345.1. Dolichopsis —, AY509943.1,
—. Macroptilium EU717268.1, EU717409.1, EU717340.1.
Mysanthus —, AY509941.1, —. Campylotropis
EU717277.1, EU717418.1, JN402864.1. Kummerowia
EU717276.1, EU717417.1, JN402866.1. Lespedeza
KJ773624.1, EU717419.1, AB538914.1. Dendrolobium —,
—, AB538884.1. Phyllodium —, HM049524.1, —. Tadeh-
agi KX527094.1, KF621106.1, KF621117.1. Desmodium
EU717280.1, EU717421.1, KM098861.1. Codariocalyx
KX527051.1, KF621099.1, KF621110.1. Hylodesmum
KF621124.1, KF621102.1, KM098857.1. Pseudarthria
KY702624.1, JF270902.1, —. Uraria JQ933516.1,
JN407137.2, KF621118.1. Christia KX527413.1,
KF621098.1, KF621108.1. Alysicarpus JN628036.1,
JQ587509.1, —. Otholobium U74219.1, JN008180.1,
EU717351.1. Psoralea AM235013.1, JN008182.1,
EU717352.1. Orbexilum —, EF549998.1, EF543345.1.
Hoita —, EF549962.1, EF543367.1. Rupertia —,
EF549999.1, EF543415.1. Psoralidium —, EF549941.1,
EU717353.1. Pediomelum JX848465.1, EF549988.1,
HM590336.1. Bituminaria U74221.1, JF501107.1,
EU717349.1. Cullen EU717254.1, EF550002.1,
EU717350.1. Sesbania Z95541.1, JX453721.1, —. Hippo-
crepis KF602185.1, JQ619986.1, KY697425.1. Securigera
KM360978.1, AF543846.1, —. Coronilla U74222.1,
JQ619970.1, HQ323870.1. Anthyllis KF602115.1,
AF543845.1, KY697485.1. Ornithopus HM850217.1,
AF142727.1, —. Lotus MG249841.1, AF142729.1,
MF314953.1. Dorycnium FR865124.1, JQ619969.1,
MF314954.1. Hammatolobium —, JQ619984.1, —.
Hebestigma —, AF543850.1, AF400134.1. Lennea
JQ591832.1, AF543851.1, AF400135.1. Gliricidia
KX119294.1, AF547197.1, AF400138.1. Poitea —,
AF547198.1, AF400141.1. Olneya —, AF543857.1,
AF529393.1. Robinia U74220.1, AF142728.1,
AF529391.1. Coursetia JQ591655.1, AF155814.1,
AF529405.1. Peteria —, AF547190.1, AF529395.1. Genis-
tidium —, AF543858.1, AF529394.1. Sphinctospermum
—, AF547191.1, AF529392.1. Glycyrrhiza AB126685.1,
AY386883.1, AF124238.1. Chesneya JQ933263.1,
JQ669609.1, AB287413.1. Gueldenstaedtia KX021596.1,
KX021479.1, KX021666.1. Tibetia KX021599.1,
JQ619951.1, —. Erophaca —, JQ619937.1, —. Oxytropis
HM142226.1, AY386915.1, LT994895.1. Biserrula —,
AY920448.1, AF126995.1. Astragalus EF685984.1,
AF142736.1, AF127001.1. Barnebyella —, JQ669593.1,
—. Colutea JQ933276.1, AY386874.1, AF126993.1. Oreo-
physa —, —, AB287415.1. Smirnowia —, JQ669579.1, —.
Eremosparton —, JQ619964.1, —. Sphaerophysa —,
JQ669581.1, AF126996.1. Lessertia MF286764.1,
AY920453.1, AF126997.1. Sutherlandia JQ025097.1,
AY386913.1, AF126994.1. Swainsona —, AF142735.1,
AF126999.1. Montigena JQ933414.1, —, —. Clianthus
JQ933270.1, AY386914.1, AF126998.1. Carmichaelia
AF308705.1, AY386873.1, MF597719.1. Galega —,
JQ669610.1, AB854528.1. Calophaca KX942277.1,
JF501109.1, AF124230.1. Caragana KX942272.1,
AF142737.1, LC309038.1. HalimodendronFJ537237.1,
JQ619947.1, AB854534.1. Alhagi —, AY386880.1,
AB854520.1. Eversmannia —, AB854573.1, AB854527.1.
Hedysarum JX848461.1, JQ669599.1, KY366138.1. Core-
throdendron —, AB854567.1, AB854522.1. Sulla
KC700648.1, —, —. Taverniera —, JQ669585.1,
KY366151.1. Onobrychis KX942280.1, AY386879.1,
KY697532.1. Sartoria —, AB854583.1, AB854535.1. Ebe-
nus —, JQ619960.1, AB854525.1. Cicer AF308707.1,
AY386897.1, JN617169.1. Parochetus JQ933432.1,
JQ619993.1, DQ311716.1. Trifolium HM850420.1,
AF522131.1, KX668031.1. Ononis KF602196.1,
AF522114.2, GQ488607.1. Melilotus KP126850.1,
AF522110.2, KX667997.1. Trigonella MG946901.1,
AF522151.2, JX274159.1. Medicago Z70173.1,
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Ulueretal. BMC Ecology and Evolution (2022) 22:45
AF522108.2, —. Vicia JN661200.1, AY386899.1,
JN617168.1. Lens KJ850239.1, AF522089.1, JN617171.1.
Lathyrus MG946891.1, AF522084.1, LC311143.1. Pisum
MG917089.1, JX505829.1, LC311179.1. Vavilovia
JX505491.1, JX505832.1, KT757953.1. Subfamily Caesal-
pinioideae: Chamaecrista AM234248.1, EU361914.1,
KR737640.1. Senna U74250.1, EU362042.1, KC479270.1.
Cassia AM234244.1, JQ619983.1, AF365092.1. Gymno-
cladus AY904373.1, EU361966.1, EU361814.1. Gleditsia
AY904374.1, AY386930.2, EU361812.1. Umtiza
AM234237.1, GU321973.1, AF365126.1. Tetrapterocar-
pon AY904372.1, JX099333.1, AY899684.1. Arcoa —,
AY386933.1, AY232787.1. Acrocarpus EU361843.1,
AY904371.1, AF365098.1. Ceratonia U74203.1,
EU361911.1, AY232782.1. Pterogyne AY904377.1,
EU362031.1, AF365074.1. Haematoxylum (Haematoxy-
lon) AY904383.1, AY386905.1, AY899696.1. Cordeauxia
AY904378.1, AY386918.2, EU361787.1. Stuhlmannia
AY904395.1, JX099335.1, EU361839.1. Mezoneuron —,
EU361903.1, KX373107.1. Pterolobium —, EU362032.1,
AF365073.1. Tara —, —, HQ011837.1. Coulteria
KU176172.1, JQ587526.1, —. Caesalpinia U74190.1,
EU361906.1, KX373109.1. Pomaria —, EU362029.1,
EU361830.1. Erythrostemon JN796934.1, JX099328.1,
JX219458.1. Poincianella JX856660.1, EU361904.1, —.
Cenostigma —, —, JX073262.1. Guilandina —,
EU361900.1, KX373104.1. Libidibia —, EU361901.1,
KX373119.1. Stahlia —, EU362050.1, EU361838.1. Ho-
mannseggia AY308531.1, JQ619977.1, JX219459.1. Sten-
odrepanum —, JX219467.1, JX219462.1. Zuccagnia
AY308547.1, JX219468.1, EU361842.1. Lophocarpinia —,
JX219466.1, JX219460.1. Balsamocarpon AY308524.1,
EU361864.1, JX219457.1. Moullava —, JX099331.1,
JX073267.1. Batesia AY904375.1, EU361869.1, —. Recor-
doxylon JQ626133.1, —, AY899699.1. Melanoxylon
AY904388.1, EU362000.1, EU361822.1. Moldenhawera
AY904390.1, EU362004.1, EU361824.1. Tachigali (Tachi-
galia) JQ625892.1, EU362040.1, KR872696.1. Arapatiella
AY904376.1, EU361859.1, EU361738.1. Jacqueshuberia
AY904392.1, EU361984.1, EU361815.1. Schizolobium
AY904398.1, GQ167770.1, AY899711.1. Bussea
AY904396.1, EU361896.2, AY899708.1. Peltophorum
AY904401.1, KX538533.1, EU361828.1. Parkinsonia
AY904403.1, EU362019.1, EF101295.1. Conzattia
AY904416.1, AY386918.2, EU361786.1. Delonix
AY904421.1, EU361928.1, KY040047.1. Colvillea
AY904425.1, EU361916.1, AY899739.1. Lemuropisum
AY904426.1, EU361991.1, AF430778.1. Pachyelasma —,
EU362013.1, AF365105.1. Erythrophleum U74205.1,
EU361948.1, JX840218.1. Dimorphandra —, EU361934.1,
AF365099.1. Mora —, EU362005.1, —. Burkea
JX572357.1, EU361895.1, EU361755.1. Stachyothyrsus
—, JX099332.1, JX073268.1. Sympetalandra —, —,
EU361840.1. Campsiandra —, EU361908.1, EU361780.1.
Chidlowia —, JX099329.1, JX073263.1. Diptychandra —,
EU361935.1, AF309478.1. Vouacapoua —, EU362063.1,
AF365110.1. Dinizia —, JX295860.1, EU361798.1. Penta-
clethra AM234250.1, AF521853.1, AF278485.1. Adenan-
thera —, AF521808.1, AF278486.1. Tetrapleura —,
AF521865.1, AY125852.1. Amblygonocarpus JX572301.1,
AF521812.1, AF278487.1. Pseudoprosopis —,
AF521861.1, AY125851.1. Calpocalyx AM234257.1,
EU361907.1, AF278483.1. Xylia JF265660.1, AF521866.1,
AY125849.1. Piptadeniastrum —, AF521857.1,
AF278488.1. Entada JQ025045.1, EU328448.1,
EU328504.1. Elephantorrhiza JF265409.1, AF521828.1,
AF278484.1. Plathymenia —, AF521858.1, AF278509.1.
Indopiptadenia JQ388196.1, —, —. Newtonia
KC628005.1, AF521848.1, —. Fillaeopsis —, AF521833.1,
AY125847.1. Cylicodiscus —, AF521819.1, AY125845.1.
Prosopis KF471677.1, AY574098.1, MG709383.1. Xero-
cladia —, EU000438.1, EU004653.1. Prosopidastrum —,
EF165252.1, AY944543.1. Piptadeniopsis —, AY944559.1,
AY944542.1. Neptunia KX119312.1, AF523090.1,
AF278495.1. Leucaena —, AY574102.1, EU439990.1.
Schleinitzia —, AF521862.1, AF278491.1. Desmanthus
—, AF521820.1, EU440011.1. Kanaloa —, AF521839.1,
AF278489.1. Calliandropsis —, AF521816.1, AF278520.1.
Dichrostachys KX119290.1, JQ024956.1, KX268182.1.
Alantsilodendron —, AF521811.1, AY125844.1. Parkia
AM234251.1, EU362018.1, AF278499.1. Anadenanthera
MH560445.1, EU812064.1, AF278486.1. Pseudopiptade-
nia JQ625948.1, DQ790637.1, FJ039253.1. Piptadenia
JQ592111.1, DQ790616.1, DQ784675.1. Parapiptadenia
—, DQ790610.1, DQ784653.1. Microlobius —,
AF521842.1, AF522960.1. Stryphnodendron JQ626052.1,
DQ790643.1, DQ784680.1. Adenopodia JF265272.1,
JF270628.1, —. Mimosa JQ591939.1, AY944555.1, —.
Mimozyganthus —, AY944557.1, AY944540.1. Acacia
KX397681.1, AF274131.1, GQ872270.1. Faidherbia
JF265429.1, HM020737.1, KY100268.1. Zapoteca
JQ592091.1, EU362064.1, JX870899.1. Calliandra
JQ591619.1, JQ587539.1, JX870877.1. Viguieranthus —,
—, JX870892.1. Macrosamanea —, —, JX870883.1.
Cojoba KJ082229.1, AY944554.1, AY944538.1. Inga
FJ173744.1, EU361980.1, JX870880.1. Cedrelinga
AM234256.1, AF521818.1, JX870873.1. Zygia
JQ625977.1, JQ626423.1, JX870900.1. Archidendron
AM234253.1, EU361860.1, KX852438.1. Paraserianthes
HM850233.1, EU812040.1, EU440016.1. Pararchiden-
dron —, AF274127.1, EU439985.1. Hydrochorea —, —,
JX870879.1. Abarema JQ626162.1, GQ981925.1,
JX870787.1. Blanchetiodendron —, —, JX870790.1. Leuc-
ochloron —, —, JX870882.1. Chloroleucon —,
JQ587561.1, AF278517.1. Cathormion —, AF274122.1,
AF522949.1. Thailentadopsis —, —, JX870889.1. Sphinga
Page 19 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
—, —, JX870887.1. Havardia JQ591981.1, AF274125.1,
KF933280.1. Ebenopsis —, AY125853.1, KF921772.1.
Pithecellobium KX119318.1, HM020740.1, JX870884.1.
Pseudosamanea JQ591566.1, AF523079.1, JX870885.1.
Samanea MH560455.1, AF523073.1, JX870886.1. Albizia
KX119255.1, EU812047.1, JX870788.1. Enterolobium
MG718296.1, AF523096.1, AF522953.1. Lysiloma
JQ591891.1, AF274126.1, KF933281.1. Subfamily Detari-
oideae: Neoapaloxylon —, —, KC479267.1. Schotia
AM235016.1, EU362037.1, AF365124.1. Barnebydendron
—, EU361868.1, AF365209.1. Goniorrhachis
AM234232.1, EU361959.1, AF365185.1. Brandzeia —,
EU361870.1, AY187226.1. Oxystigma —, —, AY958477.1.
Kingiodendron JF739130.1, EU361987.1, AF365169.1.
Gossweilerodendron —, EU361960.1, AF365166.1. Prio-
ria —, EU362030.1, AF365171.1. Colophospermum
JF265343.1, AY386894.1, AF365165.1. Hardwickia —,
EU361967.1, AY187227.1. Daniellia —, EU361927.1,
KX268175.1. Eurypetalum —, KX162081.1, AF365137.1.
Eperua JQ626198.1, EU361945.1, FJ039225.1. Augouar-
dia —, EU361862.1, AF365164.1. Stemonocoleus —,
EU362051.1, AF365178.1. Peltogyne AF308718.1,
EU362021.1, AY958483.1. Hymenaea JQ625969.1,
EU361972.1, FJ009872.1. Guibourtia JX572650.1,
EU361962.1, GQ889071.1. Hylodendron —, EU361971.1,
AF365186.1. Gilletiodendron —, EU361957.1,
AF365184.1. Baikiaea JX572322.1, EU361863.1,
AY958459.1. Tessmannia —, EU362059.1, AF365192.1.
Sindora —, EU362048.1, AY958486.1. Sindoropsis —,
EU362049.1, AF365189.1. Copaifera —, EU361919.1,
AF365181.1. Detarium AM234239.1, EU361929.1,
AF365183.1. Endertia —, EU361943.1, AF365136.1.
Lysidice —, EU361995.1, AF365152.1. Saraca
AM234238.1, EU362035.1, AF365157.1. Talbotiella
KC628128.1, EU362055.1, AF365159.1. Scorodophloeus
—, EU362041.1, KF294049.1. Crudia AM234230.1,
EU361922.1, AF365172.1. Lebruniodendron —,
KF294060.1, EU361817.1. Plagiosiphon —, EU362025.1,
KJ777465.1. Micklethwaitia —, KF294062.1, KF294045.1.
Maniltoa FJ976148.1, EU361998.1, AF365121.1. Cynome-
tra AM234231.1, EU361925.1, KF294041.1. Tamarindus
AB378731.1, EU362056.1, KJ468103.1. Intsia KF496786.1,
EU361981.1, AF365149.1. Afzelia MF437031.1,
EU361848.1, AF365130.1. Brodriguesia —, EU361890.1,
EU361750.1. Loesenera —, EU361994.1, AF233472.1.
Neochevalierodendron —, EU362006.1, AF365151.1.
Normandiodendron —, EU362007.1, AF233457.1.
Zenkerella —, EU362066.1, AF365127.1. Humboldtia
JX163311.1, EU361970.1, AF365214.1. Hymenostegia
KC685085.1, KF294458.1, AF233470.1. Leonardoxa —,
EU361992.1, AF233463.1. Amherstia AM234234.1,
AF542601.1, AF365210.1. Ecuadendron —, EU361938.1,
AF365207.1. Paloue (Palovea) —, EU362016.1,
FJ817583.1. Paloveopsis —, —, FJ817571.1. Heteroste-
mon —, EU361968.1, FJ817569.1. Elizabetha —,
EU361942.1, FJ817561.1. Brownea U74186.1,
KF794162.1, EU361753.1. Browneopsis AM234233.1,
EU361894.1, AF365199.1. Macrolobium JQ625745.1,
MF946643.1, FJ817552.1. Paramacrolobium —,
EU362017.1, AF365242.1. Cryptosepalum —,
EU361923.1, AF365258.1. Dicymbe —, EU361932.1,
JN168671.1. Polystemonanthus —, EU362028.1,
AF365226.1. Englerodendron —, EU361944.1,
AF365218.1. Anthonotha KC628021.1, KX161940.1,
AF365233.1. Berlinia KC628285.1, EU361881.1,
HM059918.1. Librevillea —, EU361993.1, KJ777457.1.
Didelotia —, EU361933.1, KJ777380.1. Gilbertiodendron
KC628266.1, —, KJ777451.1. Gilbertiodendron —,
EU362020.1, AF365243.1. Isoberlinia AM234240.1,
EU361983.1, AF365221.1. Oddoniodendron —,
EU362009.1, AF365225.1. Microberlinia —, EU362003.1,
AF365223.1. Julbernardia JX572701.1, EU361986.1,
AF365266.1. Brachystegia KU568078.1, EU361886.1,
AF365254.1. Tetraberlinia —, KX162318.1, AF365230.1.
Bikinia —, EU361884.1, AY116897.1. Icuria —,
EU361979.1, AF365232.1. Aphanocalyx AM234241.1,
EU361855.1, AF365248.1. POLYGALACEAE. Tribe Polyg-
aleae: Bredemeyera EU644699.1, EU596520.1,
GQ889062.1. Comesperma AM234179.1, EU596516.1,
GQ889068.1. Monnina AM234184.1, EU604047.1,
AM234275.1. Muraltia AJ829698.1, AM889730.1,
GQ889090.1. Polygala EU644684.1, EU596518.1,
GQ889213.1. Salomonia —, —, GQ889225.1. Securidaca
EU644681.1, EU604029.1, GQ889230.1. Tribe Mouta-
beae: Barnhartia AM234168.1, —, —. Diclidanthera —,
—, AF366955.1. Eriandra AM234170.1, EU604051.1,
GQ889070.1. Moutabea AM234169.1, JQ626362.1,
AF366966.1. Tribe Carpolobieae: Atroxima AM234175.1,
EU604049.1, GQ889057.1. Carpolobia AM234176.1,
EU604053.1, GQ889064.1. Tribe Xanthophylleae: Xan-
thophyllum AM234229.1, JN564163.1, AF367004.1.
SURIANACEAE. Cadellia L29491.1, EU604056.1,
AM234304.1. Guilfoylia L29494.1, EU604031.1,
AF367010.1. Recchia AM234270.1, EU604045.1,
AF367009.1. Stylobasium U06828.1, EU604032.1, —.
Suriana U07680.1, AY386950.1, AM234306.1. QUILLAJA-
CEAE. Quillaja U06822.1, AY386843.1, AF367008.1. OUT-
GROPUS. Zygophyllales: Bulnesia EU002275.1,
EU002172.1, AJ387947.1. Celastrales: Celastrus
KF022456.1, EU328939.1, EU328814.1. Oxalidales: Oxa-
lis JN587327.1, AF542605.1, JN620140.1. Malpighiales:
Viola JQ950611.1, JX661966.1, KU558527.1. Rosales:
Prunus AF329005.1, AF288116.1, MG773118.1. Barbeya
AJ225788.1, JF317418.1, AJ225795.1. Rhamnus L13189.2,
AF288121.1, KY193773.1. Spyridium AJ390058.1,
AF049849.1, AY998780.1. Ulmus KM361026.1,
Page 20 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
AY257536.1, MG773098.1. Morus D86319.1, AY257531.1,
KT207493.1. Ficus JQ773660.1, AY257530.1, EU191024.1.
Cannabis AF500344.1, AF345317.1, KF250352.1. Humu-
lus KM360825.1, AF345318.1, KY313870.1. Zelkova
MF706362.1, AB572497.1, MF674002.1. Fragaria
HM850009.1, AF288102.1, KU600394.1. Elaeagnus
JX848456.1, AY257529.1, HM590275.1. Hippophae
JF317488.1, JF954040.1, KU304418.1. Urtica AF500361.1,
EU002192.1, MG773116.1. Urera AF500360.1,
KF138066.1, MH358317.1. Dirachma JF317482.1,
JF317423.1, AJ225796.1. Fagales: Platycarya AY263933.1,
AF118040.1, AY147078.1. Nothofagus L13357.2,
U92860.1, AY745879.1. Gymnostoma AY033870.1,
AY191695.1, —. Casuarina AY033854.1, U92858.1,
AB817433.1. Juglans AY263932.1, MF167461.1,
MG773097.1. Morella DQ310502.1, AY491657.1,
MF503613.1. Myrica KM360891.1, AY191715.1,
GQ245143.1. Betula L01889.2, AY372027.1,
MG773096.1. Alnus NC_039930.1, AB038176.1,
MF136516.1. Ticodendron AF061197.1, U92855.1,
AY147073.1. Quercus MF044887.1, AB727873.1,
MG773106.1. Castanea AF500363.1, EF057123.1,
KF718309.1. Cucurbitales: Anisophyllea AY973487.1,
AY935923.1, AY968560.1. Combretocarpus AF127698.1,
AY968447.1, AY968561.1. Bolbostemma DQ501255.1,
DQ469139.1, DQ501264.1. Begonia U59814.1,
GU397115.1, AY238597.1. Hillebrandia U59822.1,
GU397085.1, AY968564.1. Datisca MH900512.1,
AY968449.1, AY238601.1. Octomeles L21942.1,
AY968455.1, AY968574.1. Tetrameles L21943.1,
AY968458.1, AY091831.1. Corynocarpus AF148994.1,
AY968448.1, HQ207704.1. Coriaria KF022461.1,
AB016460.1, AY091825.1. Cucumis L21937.1,
DQ785841.1, HM597059.1.
Appendix2
e Papilionoideae clades which evolved between ~ 49
and 45Ma and their descendants.
Clade 1: Candolleodendron, Swartzia; Clade 2: Peri-
copsis, Camoensia, Diplotropis, Bowdichia; Clade
3: Amicia, Zornia, Poiretia, Chaetocalyx, Nissolia,
Adesmia; Clade 4: Kotschya, Humularia, Smithia,
Cyclocarpa, Soemmeringia, Bryaspis, Aeschynomene,
Ormocarpopsis, Peltiera, Ormocarpum, Pictetia,
Diphysa, Dalbergia, Machaerium, Weberbauerella;
Clade 5: Kotschya, Humularia, Smithia, Cyclocarpa,
Soemmeringia, Bryaspis, Aeschynomene, Ormocarpop-
sis, Peltiera, Ormocarpum, Pictetia, Diphysa, Dalbergia,
Machaerium; Clade 6: Kotschya, Humularia, Smithia,
Cyclocarpa, Soemmeringia, Bryaspis, Aeschynomene,
Ormocarpopsis, Peltiera, Ormocarpum, Pictetia,
Diphysa; Clade 7: Centrosema, Clitoria, Dalbergiella;
Clade 8: Ptycholobium, Mundulea, Chadsia, Tephrosia,
Apurimacia, Lonchocarpus, Muellera, Derris, Parader-
ris, Fordia, Hesperothamnus, Piscidia, Gompholobium,
Pongamiopsis, Erichsenia, Viminaria, Philenoptera, Lep-
toderris, Deguelia, Millettia, Galactia, Rhodopis, Dio-
clea, Canavalia, Aganope, Ostryocarpus.
Supplementary Information
The online version contains supplementary material available at https:// doi.
org/ 10. 1186/ s12862- 022- 02003-y.
Additional le1. S1. Chronogram of Fabales.
Additional le2. S2. Lagrange results of ancestral area reconstructions.
Additional le3. S3. Input matrix for ancestral area analysis.
Additional le4. S4. Input matrix for flower type analyses.
Additional le5. S5. Input matrix for presence or absence of a pentamer-
ous corolla analysis.
Additional le6. S6. Input matrix for presence or absence of three types
of petals analysis.
Additional le7. S7. Input matrix for presence or absence of enclosed
reproductive organs analysis.
Additional le8. S8. Input matrix for presence or absence of a bilateral
symmetry analysis.
Additional le9. S9. Input matrix for androecium type analysis.
Additional le10. S10. Input matrix for inflorescence type analysis.
Additional le11. S11. Input matrix for the smallest flower size analysis.
Additional le12. S12. Input matrix for the largest flower size analysis.
Additional le13. S13. Input matrix for the smallest height analysis.
Additional le14. S14. Input matrix for the largest height analysis.
Additional le15. S15. Input matrix for habit analysis.
Additional le16. S16. Sources used to construct ancestral state analy-
ses of Fabales.
Acknowledgements
We are grateful to Dr. Colin Hughes and Dr. Chris Venditti for their constructive
suggestions, and Dr. Patrick S. Herendeen for valuable fossil clarifications.
Author contributions
JAH conceived and designed the research. DAU performed the research, ana-
lyzed the data, and wrote the manuscript. JAH, FF and SA advised on methods
and project design. JAH and FF provided the materials. All authors interpreted
the results. All authors read and approved the final manuscript.
Funding
The first author is funded by Republic of Turkey Ministry of National Education.
The funding body played no role in the design of the study and sample collec-
tion, analysis, and interpretation and in writing the manuscript.
Availability of data and materials
All data generated or analysed during this study are included in the Additional
files 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16.
Declarations
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Page 21 of 24
Ulueretal. BMC Ecology and Evolution (2022) 22:45
Competing interests
The authors declare that they have no competing interests.
Author details
1 School of Biological Sciences, Lyle Building, University of Reading, Whitek-
nights, Reading, Berkshire RG6 6BX, UK. 2 Royal Botanic Gardens, Kew, Rich-
mond, Surrey TW9 3DS, UK. 3 School of Biological Science, University of Ports-
mouth, King Henry Building, King Henry I Street, Portsmouth PO1 2DY, UK.
Received: 14 October 2020 Accepted: 5 April 2022
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... The data presented in this paper is supporting the research article "Reconstructing an historical pollination syndrome: keel flowers" (Aygören Uluer et al., 2022). We present a dataset containing information on number of species, geographic distribution, floral type (keeled or not), presence or absence of fused petals, floral symmetry, presence or absence of a pentamerous corolla (petals + petaloid sepals in Polygalaceae), androecium type, presence or absence of enclosed reproductive organs, presence or absence of three distinct petal types (petals + petaloid sepals in Polygalaceae), flower size, corolla size (i.e., in open flower) and/or filament size (i.e., entire filament size particularly in subfamily Caesalpinioideae), flower colour, UV reflectance, habit, height, inflorescence type and inflorescence size for 758 Fabales genera. ...
... • The dataset we present contains information of the 15 morphological traits were selected as potentially the most important from the point of view of a pollinator: floral type (keeled or not), presence or absence of fused petals, floral symmetry, presence or absence of a pentamerous corolla (petals + petaloid sepals in Polygalaceae), androecium type, presence or absence of enclosed reproductive organs, presence or absence of three distinct petal types (petals + petaloid sepals in Polygalaceae), flower size, corolla size (i.e., in open flower) and/or filament size(i.e., entire filament size particularly in subfamily Caesalpinioideae), flower colour, UV reflectance (e.g., FReD: the floral reflectance database) [8] , habit, height, inflorescence type and inflorescence size. • Some parts of the data presented in this paper was used for analyses in Aygören Uluer et al. [1] . However, other parts, such as, flower colour, UV reflectance, number of species, corolla/filament size are newly added. ...
... The information was obtained from every appropriate, previously published source, and the list of publications used here can be found at the end of the dataset table. Further details about the experimental design, materials and methods related to data are described at Aygören Uluer et al. [1] . ...
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The consequences of the Cretaceous-Paleogene (K-Pg) boundary (KPB) mass extinction for the evolution of plant diversity are poorly understood, even although evolutionary turnover of plant lineages at the KPB is central to understanding the assembly of the Cenozoic biota. One aspect that has received considerable attention is the apparent concentration of whole genome duplication (WGD) events around the KPB, which may have played a role in survival and subsequent diversification of plant lineages. In order to gain new insights into the origins of Cenozoic biodiversity, we examine the origin and early evolution of the legume family, one of the most important angiosperm clades that rose to prominence after the KPB and for which multiple WGD events are found to have occurred early in its evolution. The legume family (Leguminosae or Fabaceae), with c. 20.000 species, is the third largest family of Angiospermae, and is globally widespread and second only to the grasses (Poaceae) in economic importance. Accordingly, it has been intensively studied in botanical, systematic and agronomic research, but a robust phylogenetic framework and timescale for legume evolution based on large-scale genomic sequence data is lacking, and key questions about the origin and early evolution of the family remain unresolved. We extend previous phylogenetic knowledge to gain insights into the early evolution of the family, analysing an alignment of 72 protein-coding chloroplast genes and a large set of nuclear genomic sequence data, sampling thousands of genes. We use a concatenation approach with heterogeneous models of sequence evolution to minimize inference artefacts, and evaluate support and conflict among individual nuclear gene trees with internode certainty calculations, a multi-species coalescent method, and phylogenetic supernetwork reconstruction. Using a set of 20 fossil calibrations we estimate a revised timeline of legume evolution based on a selection of genes that are both informative and evolving in an approximately clock-like fashion. We find that the root of the family is particularly difficult to resolve, with strong conflict among gene trees suggesting incomplete lineage sorting and/or reticulation. Mapping of duplications in gene family trees suggest that a WGD event occurred along the stem of the family and is shared by all legumes, with additional nested WGDs subtending subfamilies Papilionoideae and Detarioideae. We propose that the difficulty of resolving the root of the family is caused by a combination of ancient polyploidy and an alternation of long and very short internodes, shaped respectively by extinction and rapid divergence. Our results show that the crown age of the legumes dates back to the Maastrichtian or Paleocene and suggests that it is most likely close to the KPB. We conclude that the origin and early evolution of the legumes followed a complex history, in which multiple nested polyploidy events coupled with rapid diversification are associated with the mass extinction event at the KPB, ultimately underpinning the evolutionary success of the Leguminosae in the Cenozoic.
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The adaptive significance of different types of inflorescences in flowering plants has been largely ignored. The few published studies investigating adaptive aspects of floral displays suggest that numbers of flowers and their arrangement in space and time determine levels of pollination and fruit-set in natural populations. The frequently conflicting demands placed on inflorescence architecture have led to an evolutionary compromise that maximizes the genetic contribution of an individual plant to the next generation. These conflicting demands include pollinator attraction vs. ovary competition, fruit dispersal vs. fruit predation, and reproductive vs. vegetative resource allocation. In most cases, the inflorescence size most successful in fruit production is also the most frequent in natural populations. In addition to quantity of offspring, inflorescence architecture affects, and in turn is affected by, the quality of offspring that result from selfing vs. outcrossing.