Andressa Cabral, Federico Luebert and Renato Mello-Silva

1. Phylogeny, biogeography and taxonomy of the
Barbacenia
inselbergs group (Velloziaceae)
Aluna: Andressa Cabral
Orientador: Prof. Dr. Renato de Mello Silva
Co-orientador: Dr. Federico Luebert
Filogenia, biogeografia e taxonomia do grupo
Barbacenia
dos inselbergues (Velloziaceae)
1Universidade de São Paulo, Departamento de
Botânica, São Paulo, SP, Brazil.
2Nees-Institut für Biodiversität der Pflanzen,
Universität Bonn, Bonn, German.
3Departamento de Silvicultura y Conservación
de la Naturaleza, Universidad de Chile,
Santiago, Chile.
Evidence for morphological evolutionary stasis in a
Middle Miocene Inselbergs clade of Barbacenia
(Velloziaceae)
Andressa Cabral1, Federico Luebert2,3 and Renato Mello-Silva1

2. Inselbergs are Precambrian granite and gneiss outcrops that occur mainly in tropical and subtropical regions. Distributed along the east coast of South
America, the Atlantic Forest Domain houses a widespread number of Inselbergs (hereafter AFI), composed by Campos de Altitude and Inselbergs “sugar
loaf lands”. These environments are dominated by shrublands, grasslands and rocky outcrops and display high levels of endemism and plant richness
(Safford and Martinelli 2000).
Among the most conspicuous elements of Inselbergs is Velloziaceae, a monocotyleon family which comprises heliophyte plants (Smith, 1962) adapted to
xeric conditions and to specific substrates (Behnke et al., 2013). According to previous phylogenetic inferences for the family (e.g., Alcantara et al. 2018),
Barbacenia was recovered as two main clades, one comprising only endemic species from AFI and its sister clade including mainly Campos Rupestres
(CR) species. Intriguingly, the diversity of Barbacenia species is quite assymetric among clades (Mello-Silva in FDB 2020) and perhaps different factors
were important drivers in the diversification of these sister clades, likely leading to different patterns of morphological diversification. However, whereas
the available phylogenetic inferences had not included all Barbacenia species that occur in AFI, the evidence for its evolutionary and biogeographical
history is still limited. Therefore, we investigated here the evolutionary relationships, biogeographic history and morphological diversity among
Barbacenia lineages.
Introduction
Figure 1. Atlantic Forest Inselbergs. a-b. Pico dos Marins (São Paulo state, SP); c. Morro do Aghá (Espírito Santo, ES); d. Águia Branca (ES); e. Niterói (Rio de Janeiro, RJ).
a b c d
a b c d e f
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a b
Figure 2. Barbacenia species from Atlantic Forest Inselbergs. a. B. irwiniana; b-c. B. pabstiana; d. B. rogieri; e-f. B. squamata. Photos: a - J. Lovo; d - L. Menini-Neto; f – G.P. Coelho.

3. PCR using the primers
atpb-rbcL, trnH-psba, trnL-
trnF and ITS.
88 new sequences + 632
Genbank sequences.DNA extractions.
Phylogenetic inferences using MrBayes
v.3.2.6 and RAxML-HPC BlackBox 8.2.12.
Estimate of the divergence times using
2 calibration points in BEAST 1.8.4.
Ancestral range estimation
analyses through
BioGeoBears v.1.1.2.
Coordinates cleaned through
CoordinateCleaner v.2.0-13.
Coordinates from GIBF, field trips
and exsiccata labels.
Biogeography
Morphology
Phylogeny
Morphological matrix
with 16 characters
(general morphology
and anatomy of leaf and
pedicel) for 50
Barbacenia species.
Morphological mapping for
each character in a ML tree
using ape v.5.3.
Material & Methods
Morphological diversity analysis
using ade4 v.1.7-13, cluster
v.2.1.0 and vegan v.2.5-6.
Sample of material 20 specimens, including all type locations, were collected during field trips in AFI areas.
Alignments using PhyDE v.0.9971.
Figure 3. Morphological data sources a.
Barbacenia mantiqueirae; b-c. B. fanniae.
a c
bb
b
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4. Results
Two major groups were recovered in Barbacenia, one including the endemic species from
AF Inselbergs (PP = 1.0, BS = 89), and the second comprising most of the Campos
Rupestres endemic species (PP = 0.68, BS = 66). Within the both groups, five well-
supported clades were recognized.
DEC analysis indicates that the diversification of Barbacenia likely took place during the
Middle Miocene, in the Atlantic Forest and Cerrado domains (AAP = AC 77,29%).
Barbacenia AFI ancestor arose during the Middle Miocene and was already distributed in
AFI areas (AAP = B 53,53% or AB 45,08%). Barbacenia CR ancestral lineage arose also
during the Middle Miocene more likely only in Campos Rupestres areas (AAP = DE
50,21% or AAP = DF 24,64%), or in Guyana Shield and Southern Espinhaço (AAP = CD
24,39%).
The first two principal coordinates of the PCo explained 25.9% and 8.6% of the total
variance, respectively. The AFI clade occupied a significantly smaller proportion of
morphospace than the CR clade in the three analyses. This was corroborated by the
pairwise permutation tests, which suggest that morphological disparity is significantly
different between both clades (P<0.001)
Figure 4. Morphospace occupancy of Barbacenia. a–c. Distribution of clades in the first two axes of the PCo
analyses: a, all characters; b, vegetative characters; c, reproductive characters; 1, AFI clade; 2, CR clade.
Figure 5. Ancestral area reconstruction of Barbacenia with DEC model,
based on the BEAST maximum clade credibility tree. Pie charts show the
relative probability of each range. Letters next to nodes are the ancestral
ranges with the greatest relative probability.
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5. Discussion & Conclusions
The results obtained in the present study also provide evidence for a diversification of Barbacenia from the Middle Miocene. This diversification coincides
with the exposure of Inselbergs surface and the spread of open habitats in the current area of the Atlantic Forest during the Miocene, which may have
caused the first expansion of the geographical range of AFI Barbacenia. Subsequently, paleovegetational dynamics during the pleistocene climatic
fluctuations may also have contributed to the dispersion and speciation process in Barbacenia AFI lineages. We suggest that stepping-stone dispersal
across mountaintops was the key for the range expansion of this group. These dispersals were possibly limited by niche conservatism and ecological
preferences for rocky environments, which together with their geographical isolation, could explain the endemism of several species to single inselbergs.
Moreover, Barbacenia AFI clade exhibits a homogeneous morphology, and provides an interesting example of long-term morphological stability or
morphological stasis. Low genetic connectivity has been repeatedly verified in different groups in the AFI, corroborating that Inselberg species are
maintained as discrete evolutionary units. We propose that the differences in morphological disparity between these lineages were influenced by
environmental heterogeneity and biome-specific paleovegetational dynamics during these periods.
Figure 6. Highlands of the Rio de Janeiro state. Photo: R. Freitas.
Figure 7. Representation of stepping-stones dispersal across mountaintops.
Figure 8. Barbacenia species, showing their preferences for rocky environments. a. B.
gounelleana; b. B. irwiniana; c. B. rogieri. Photos: a – M. Trovó; b - J. Lovo; c - L. Menini-Neto.
a b c
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