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This study presents preliminary results on the pollination strategy and re-productive success of the tertiary relict and endemic species Haberlea rhodopen-sis Friv., Gesneriaceae in a highly fragmented habitat in Bulgaria and Greece. The flowers of the species receive very scarce insect visits, mainly from non-specialized insects. The species is obviously not attractive to honeybees and bumblebees and we could not find a specific pollinator. Flowers offer pollen and scarce nectar as a reward. Pollination success is characterized by high seed production and rate of pollination.
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Доклади на Българската академия на науките
Comptes rendus de l’Acad´emie bulgare des Sciences
Tome 66, No 10, 2013
Katerina Bogacheva-Milkoteva, Ekaterina Kozuharova,
Regine Claßen-Bockhoff, Andrej Gogala∗∗
(Submitted by Academician V. Golemansky on May 28, 2013)
This study presents preliminary results on the pollination strategy and re-
productive success of the tertiary relict and endemic species Haberlea rhodopen-
sis Friv., Gesneriaceae in a highly fragmented habitat in Bulgaria and Greece.
The flowers of the species receive very scarce insect visits, mainly from
non-specialized insects. The species is obviously not attractive to honeybees
and bumblebees and we could not find a specific pollinator. Flowers offer pollen
and scarce nectar as a reward. Pollination success is characterized by high seed
production and rate of pollination.
Key words: Haberlea rhodopensis, pollination, nectar, seed set
The study was conducted with the financial support of a project of Deutsche Bundesstiftung
Umwelt, Medical University of Sofia and Johannes Guthenberg University of Mainz, 2011.
Introduction. Haberlea rhodopensis is an endemic species of the Balkans.
It is a resurrection plant, belonging to the tropical family Gesneriaceae. In Eu-
rope there are only three genera of the family: Haberlea (in Bulgaria and Greece),
Ramonda (Balkan Peninsula and Pyrenees) and Jankaea (in Greece) [1]. All of
them are tertiary relicts, having evolved under climatic conditions, which differ
strongly from the recent ones. The flora of Southeastern Europe, the Early to
Middle Miocene flora, was rich, diverse in thermophilous elements, consisting of
polydominant mesophytic to hygromesophytic forests. Climatic changes after the
Miocene climatic optimum caused changes in the floristic composition and veg-
etation structure, characterized by a decrease in the abundance of palaeotropic
and thermophilous elements, a reduction of macrothermic elements, and the dis-
appearance of evergreen laurel forests. Together with these changes, the role of
arctotertiary species in plant communities in the mesophytic forests increased.
Major vegetation changes occurred in the late Miocene, under more diverse cli-
matic conditions [2].
The flowers of H. rhodopensis have a prominent entomophilous syndrome,
namely of a “gullet” type with pollen transferred nototribically [3–5] (Figs 1, 2)
and our previous studies show that they are incapable of self-pollination. Obser-
vations on actual pollination in the Gesneriaceae are scanty [3]. With regard to
the European representatives, there are studies on the pollination biology of the
related species Jankaea heldreichii [6], some observations on honeybee influence
on Haberlea rhodopensis [7] and on Ramonda myconi [8]. Therefore, it is of great
interest for the development of conservation strategies for the species to study its
pollination characteristics in the context of its relict nature, fragmented habitat
and the challenges of the changing environment.
Molecular analysis with nuclear and plastid markers for molecular analysis
of five actinomorphic genera in the Old World Gesneriaceae shows that floral
actinomorphy in the family has evolved convergently in different alliances. The
authors hypothesize that the evolution from zygomorphy to actinomorphy, with
novel combinations of characters, is possibly due to shifts in pollination strate-
gies, such as a switch from nectar to pollen rewards and a switch to generalist
pollinators. It is suggested that Haberlea rhodopensis might be a relict of the
stock from which the actinomorphic flowers of Ramonda evolved [9].
It has been argued that many of the ways in which humans disturb natural
habitats are likely to disrupt plant-pollinator interactions, with consequent out-
cross pollen limitation, and that the ecological context of anthropogenic pollen
Fig. 1. Flower visitors of Haberlea rhodopensis. Left to right, first row: Pollinating
Lasioglossum morio.L. morio with pollen load. Left to right, second row: Syrphids
were frequent flower visitors. Evidence for predation on the flowers
1428 K. Bogacheva-Milkoteva, E. Kozuharova , R. Claßen-Bockhoff et al.
limitation can generate diverse selective forces on plant mating systems. In
many cases, we expect an evolutionary shift towards higher frequencies of self-
fertilization, although the selective forces and traits involved are likely to vary
with the nature of the disturbance. It will be particularly important to deter-
mine whether human disturbance is qualitatively different from natural factors
that cause PL and whether plant populations have the demographic and genetic
capacity for evolutionary responses adequate to ensure persistence in changing
environments [10 ].
Pollination systems are often more generalized and dynamic than the con-
cept of “pollination syndromes” suggests. Moderate to substantial generalization
often occurs. Plant generalization is predicted by a simple model: as long as tem-
poral and spatial variance in pollinator quality is appreciable, different pollinator
species do not fluctuate in unison and they are similar in their pollinator effec-
tiveness. In conservation biology, generalized pollination systems imply resilience
to linked extinctions, but also the possibility that introduced generalists might
displace natives with a net loss of diversity [11].
Flowers in six communities from three continents were scored for expression
of floral traits used in published descriptions of the pollination syndromes, and
simultaneously the pollinators of as many species as possible were characterized.
Ordination of flowers in a multivariate “phenotype space”, defined by the syn-
dromes, showed that almost no plant species fell within the discrete syndrome
clusters. Furthermore, in approximately two-thirds of the plant species, the most
common pollinator could not be successfully predicted by assuming that each
plant species belongs to the syndrome closest to it in the phenotype space. A
fresh look at how traits of flowers and pollinators relate to visitation and pollen
transfer is recommended [12].
In our study, we compared native populations and plants grown ex situ in
the Botanical Garden of Mainz University. We tested: 1) the identity of the pol-
linator agent; 2) the nature of the reward; 3) the extent to which the abundance
of the fruit and seed set could be used as estimators of pollination success.
Materials and methods. The study sites. The population at Ustovo
district is situated in the Central Rhodope Mts, at 800 m. a.s.l., along Cherna
River, on limestone rocks in broadleaf forest with meadows nearby. Co-flowering
genera during the observation time in the range of 30 m were: Taraxacum offici-
nale L., Geranium sp., Alliaria sp., Lamium sp., Veronica sp., Crataegus monog-
yna Jacq., Syringa vulgaris L., Apium sp., Rhinantus sp., Sambucus nigra L. The
weather during the observation period was mostly cloudy, with rain and storms
Fig. 2. Flower visitors of Haberlea rhodopensis – small size generalist insects
Compt. rend. Acad. bulg. Sci., 66, No 10, 2013 1429
in the afternoon with temperatures at noon between 11.5 C and 22 C. In the
period between 8.06. and 10.06.2012, the weather was sunny with temperatures
22–30 C.
The population in the village of Nenkovo is situated in the Eastern Rhodope
Mts, at 400 m a.s.l., along Borovitsa River, on limestone rocks in an open area
near meadows. Co-flowering genera during the observation time in the range of
30 m were: Malus sp., Prunus sp., Salix sp., Alnus sp., Muscari sp., Veronica
sp., Viola sp., Geranium sp. The weather was sunny, with temperatures of about
18.5 C.
The cultivated population in the Botanical Garden of Mainz University is
in the alpinum of the garden at about 90 m a.s.l. A bumblebee nest was near
the stand of Haberlea rhodopensis. The weather was rainy, with temperatures of
about 14 C between 26 and 29.04.2012, and in the period 29.04.2012–06.05.2012
there was warm (23 C) and sunny weather.
Pollinators/visitors. The tests were performed according to standard
methods [13]. Most observations were conducted in 2010–2012, during the flow-
ering period from April to July. For in situ observations we chose two natural lo-
calities in Central and Eastern Rhodope Mts Bulgaria, and a population from the
Botanical Garden at Johannes–Gutenberg University in Mainz, Germany. The
total observation time of 52 h was adjusted according to the peak of flowering
of the populations and distributed during the periods 16.05.2010–20.05.2010 and
01.06.2012–10.06.2012 at Ustovo district, 24.04.2010–26.04.2010 in the village of
Nenkovo and 26.04.2012–06.05.2012 in the Botanical garden of Mainz from 08.00
till 22.00 h. We used the transect method [9]. Previous sporadic observations in
four more localities in Rhodope Mts in 2008 and 2009 (villages of Beden, Trigrad
and Yagodina) supplied additional information for the study.
Reward – nectar presence and concentration. We obtained preliminary
results on nectar presence in the flowers of H. rhodopensis, using glucose test
strips. In the second phase of the study, nectar concentration was measured at
different times of the day on bagged and free flowers with hand refractometer
Eclipse 0–50% Sucrose. For estimating nectar quantity, we used glass capillaries
of 1 µl, 2 µl, 5 µl and 10µl.
Pollination success. Pollination success was evaluated by: a) free pollina-
tion fruit set of a random sample; we collected randomly 36 inflorescences with
177 flowers from four sampling sites at the village of Yagodina and the village
of Trigrad in Rhodope Mts; b) seed set per fruit of a random sample on plants
of different sampling sites; we counted the seeds, non-developed ovules and dam-
aged seeds from a total of 27 capsules from four different sampling sites. For each
sampling site, we calculated the average for each category.
Results and discussion. Pollinating agents. Our observation showed
very scarce insect visits, even at the peak of flowering of the population and at
a time of high insect activity. Honeybees and bumblebees avoid the flowers of
1430 K. Bogacheva-Milkoteva, E. Kozuharova , R. Claßen-Bockhoff et al.
Fig. 3. Pollination rate of a random sample of H. rhodopensis
Haberlea rhodopensis and visit other co-flowering species. They rarely approach
the flower and do not try to reach pollen or nectar. We compared the populations
of H. rhodopensis and Veronica sp. in Ustovo district, a distance of 1 meter apart,
undertaking 40 min observation in conditions of high insect activity. Veronica sp.
received 18 visits by Apis meliffera, while H. rhodopensis received 3 visits with
duration of no more than two seconds. Many insects approach the flowers without
trying to get inside. In the Botanical Garden of Mainz, a bumblebee nest was
near the site, but the bumblebees did not visit the flowers of H. rhodopensis.
In both natural habitats, we found many small-size visitors, probably us-
ing the flowers as shelter or feeding on pollen – ants, caterpillars, beetles, flies
(Formicidae, Coleoptera, Diptera, larvae, Fig. 2). We found evidence for preda-
tion, pollen or nectar robbing. In the Botanical Garden in warm and dry weather
(temperatures above 23 C), in addition to the above-mentioned, we noted reg-
ular pollination visits by Lasioglossum morio (Fabricius 1793), collecting pollen,
storing it and moving from flower to flower. A group of five H. rhodopensis indi-
vidual flowers received 20 visits in 20 min. Similarly high activity was observed
during four days of warm weather between 10 a.m. and 12 at noon. Additionally,
syrphids were active flower visitors (Fig. 1).
Compt. rend. Acad. bulg. Sci., 66, No 10, 2013 1431
Fig. 4. Seed set per fruit of H. rhodopensis
Flowers do not close at night, but by observations after sunset between 6
p.m. and 10 p.m. we could not find any insects at any of the experimental sites.
Despite its typical bee flower characteristics – corolla blue (rarely white) with
yellow spots in the mouth, tube widening above, limb bilabiate, nectary annu-
lar (Weber) – Haberlea rhodopensis is obviously not attractive to bumblebees or
honeybees, as our observations in situ revealed. Our previous studies on the pol-
linators of this plant species show that honeybees do not visit its flowers. The
species receives no insect visits except single nectar-collecting Bombus terrestris
Linnaeus queen and we suggested that pollination is accomplished by nectar-
collecting bumblebee queens with long proboscises [7]. This corresponds with
studies on the closely related species Jankaea heldreichii. The plant is an insect-
pollinated generalist without any particular relationship with its insect partners.
J. heldreichii receives scarce visits only from bumblebee queens – Bombus lu-
corum, Pyrobombus soroeensis and P. pratorum [6]. Ramonda myconi, another
sister species to Haberlea rhodopensis, is mainly visited by bumblebees and syr-
phids (M. Riba and F.X. Pic´o, unpublished result). Insects involved in the pol-
lination of the Gesneriacese include bees (Apiidae, Euglossini in the neotropics,
Anthophoridae, Xylocopinae, etc.), rare butterflies and very rare moths. Wasps,
dipterans, gnats, etc. are not so far definitely known as pollinators; they probably
1432 K. Bogacheva-Milkoteva, E. Kozuharova , R. Claßen-Bockhoff et al.
play an insignificant role, if any at all [3]. In the recent climatic conditions the
plants exist as clone-populations. That is why geitonogamy is probable.
Reward. Haberlea rhodopensis has a strikingly orange-coloured nectar disc,
but we noted a very low quantity of nectar <1µl per flower. Nectar concentration
varied between 10 and 42% sucrose, but concentrations above 15% were noted only
in sunny weather with temperatures of above 23 C. We suppose that nectar is
produced in the morning, since the highest concentrations are measured between
9 a.m. and 12 at noon. There was no difference between bagged and free flowers.
The flowers had a very weak scent.
Flowers of Gesneriaceae are primarily nectar flowers. Lack of nectar (rather
rare) is a phylogenetically secondary condition. There are taxa in which the
nectary is non-functional or completely reduced – deceptive nectar flowers and
pollen flowers. Attraction of pollinators is primarily by visual cues. Most of
the flowers are devoid of any floral scent [3]. The genera Ramonda and Jankaea
do not have nectaries [3, 6]. Possibly Haberlea rhodopensis is on the way to lose
its nectar, due to changes in the pollinator complex. Haberlea rhodopensis flow-
ers are self-compatible but do not self-pollinate spontaneously. This plant pos-
sesses the ability for vegetative propagation by sending thin, horizontal rhizomes
(Bogacheva-Milkoteva, Kozuharova, in press).
Pollination success. From the 177 flowers tested for pollination rate, 141
(79.6%) had fruits, 29 (16.4%) were not pollinated and 7 (4%) were predated.
We recorded an average of 768 (Ncapsules = 27) ovules per fruit. An average
of 458 (59.8%) of them matured to seeds. An average of 232 (30.3%) unset ovules
per fruit were counted. An average of 76 (9.9%) predated or damaged ovules
per fruit were counted. Generally in Gesneriaceae seeds are produced in great
numbers, are small and have little nutrition storage [3]. R. myconi fruits contain
many small seeds (on average 500 seedsper capsule; M. Riba, unpublished result).
In Jankaea heldreichii, the number of seeds per capsule varies between 134 and
613. Just 50% of the flowers of J. heldreichii survive to fruiting stage [6].
Conclusion. The hypothesis for the pollination syndromes [4, 5] predicts
that flowers with a definite complex of flower traits are linked to definite type of
pollinators. According to this hypothesis, Haberlea rhodopensis flowers should be
pollinated by bees. However, we could not observe such a relationship. In situ
practically no visitors were observed, except a sporadic one by a nectar-collecting
queen Bombus terrestris Linnaeus [6]. However, the pollination is effective, if we
take into account the results from reproductive success. Ex situ we found only
non-specialized visitors and the only bee species we observed was Lasioglossum
morio, Fig. 1. This social bee is a polylectic [14], widely distributed species [15].
It was a frequent visitor to all flowers in the Botanic Garden.
Our hypothesis. Haberlea rhodopensis is a Tertiary relict which, due to its
desiccation tolerance and abilities for vegetative propagation, survived dramatic
climate changes. During these climatic changes, the local flora changed. This
Compt. rend. Acad. bulg. Sci., 66, No 10, 2013 1433
is probably connected with shifts in the pollinator complexes. In many cases,
when there was a specialization to a particular pollinator, because of the climatic
changes, the flowers had to switch to more generalized pollination system. Rarely
has the path of adaptation to mainly pollen-feeding insects been taken. In the
Balkans, Gesneriaceae relicts are such an example of adaptation traits. Haberlea
rhodopensis has small nectar quantity and lacks specialized visitors in spite of
the zygomorphic flower. Jankaea could be regarded as the “missing link” in the
evolution of the European Gesneriaceae (zygomorphic but without nectary) and
Ramonda is the next stage – a typical pollen flower.
A similar evolutionary trend is observed in Dalechampia (Euphorbiaceae)
vines. There is molecular phylogenetic evidence for an evolutionary shift in
Dalechampia from a highly specialized relationship with resin-collecting bees to
generalized pollination by a variety of pollen-feeding insects. This shift was associ-
ated with dispersal from Africa to Madagascar, where the specific resin-collecting
pollinators are absent. These results show that plants dispersing beyond the
range of their specific pollinators may succeed by evolving more generalized pol-
lination systems. Recent fieldwork in Madagascar has shown that the species
of Dalechampia found there offer only pollen as a reward for pollinators, and
that most are pollinated by a variety of pollen-feeding insects, including beetles
(Cerambycidae, Scarabidae), muscoid flies (Diptera) and several bees (Halictidae,
Anthophoridae, Apidae). It seems that resin-collecting megachilid bees, which are
the only pollinators of Dalechampia in Africa, failed to colonize Madagascar. The
ancestral Dalechampia colonists of Madagascar were probably pollinated inciden-
tally by other pollen-feeding insects. They subsequently adapted to the absence
of their specific pollinators by losing the gland that secretes the resin reward and
by effectively using diverse pollen-feeding insects as pollinators. These changes
were sufficiently successful to allow secondary diversification on the isolated is-
land of Madagascar [16]. Historical climate change influences the modularity
and nestedness of pollination networks, although this possibility remains poorly
tested. This lack of research is in sharp contrast to the considerable efforts to
disentangle the role of historical climate change and contemporary climate on
species distributions, richness and community composition patterns. On the ba-
sis of a global database of pollination networks, it is shown that historical climate
change is at least as important as contemporary climate in shaping modularity
and nestedness of pollination networks. Specifically, on the mainland is found
a relatively strong negative association between Quaternary climate change and
modularity, whereas nestedness is most prominent in areas having experienced
high Quaternary climate change [17].
What we have to take into account is how viable the seedlings are. Our
observations show that in nature very few seedlings survive. Possibly the seedlings
cannot compete effectively with the other vegetation. Alternatively, perhaps, they
have specialized to mycorrhiza, like the orchids, which are well known for their
1434 K. Bogacheva-Milkoteva, E. Kozuharova , R. Claßen-Bockhoff et al.
symbiosis requirements [18]. The seeds of Haberlea rhodopensis are also numerous
and tiny. These are implications for our further research.
Jankaea heldreichii occurs only in Mt. Olympus, Haberlea rhodopensis
reaches further, more to the north in the Rhodope and Stara Planina Mts and
Ramonda serbica, being least specialised with regard to pollinators, is found on
northernmost sites. One possible explanation for the distribution pattern of Ges-
neriaceae members on the Balkans could be their pollination adaptations, together
with other environmental requirements.
Acknowledgements. We express our gratitude to Frank O’Reilly, B.A.,
Ph.D (Uni. London) for the correction of the English language.
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Department of Pharmacognosy
Faculty of Pharmacy
Medical University of Sofia
2, Dunav Str.
1000 Sofia, Bulgaria
Johannes Gutenberg-University
Institut f¨ur Spezielle Botanik
55099 Mainz, Germany
∗∗Slovenian Museum of Natural History
Preˇsernova 20, p.p. 290
SI-1001 Ljubljana, Slovenia
1436 K. Bogacheva-Milkoteva, E. Kozuharova , R. Claßen-Bockhoff et al.
... These herbaceous genera appear to have survived in cliffs, screes and crevices of the southern European mountain chains (Pyrenees, Balkan and South-western Alps): Ramonda, Haberlea and Jankaea (Gesneriaceae); Borderea (Dioscoreaceae); Xatartia and Endressia (Apiaceae) and Berardia (Asteraceae-Ozenda 2009). These taxa are considered paleo-endemics based on several lines of evidence: fruit features in Xatardia (Sáenz de Rivas 1977) and distinctive vegetative and reproductive life history (andromonoecism in Endressia-Schlessmann 2010; monocarpism in Xatardia -Dajoz 1989; long-lived life cycle in Borderea- García et al. 1995; desiccation tolerance in Ramonda and Haberlea- Rakić et al. 2013;Bogacheva-Milkoteva et al. 2013b). The relictual nature of Berardia subacaulis Vill. ...
... pyrenaica Miégev.-García et al. 1995, 2012), while the Gesneriaceae genera Haberlea, Jankaea and Ramonda are mainly visited by Hymenoptera (Bogacheva-Milkoteva et al. 2013b;Picó and Riba 2002;Vokou et al. 1990). These paleo-endemics show a low pollinator frequency as detected in Berardia subacaulis. ...
... Haberlea rhodopensis Friv. (Bogacheva-Milkoteva et al. 2013b) and Jankaea heldreichii Boiss. (Vokou et al. 1990) are characterized by zygomorphic flowers, pollinated only from bumblebee queens but without any particular relationship with their insect partners. ...
Climate change is known to have a profound influence on plant reproduction, mainly because it affects plant/pollinator interactions, sometimes driving plants to extinction. Starting from the Neogene, the European climate was subjected to severe alterations. Nevertheless, several genera, including Berardia, survived these climatic changes. Despite the numerous studies performed about the relationship between climate change and plant reproductive biology, equivalent studies on ancient species are lacking, even though they may furnish crucial information on the strategies that allowed them to survive drastic climatic fluctuations. We investigated floral and reproductive features in Berardia subacaulis (Asteraceae), describing pollen vectors, capitulum and florets phenology, evaluating reproductive efficiency and defining the reproductive mode of the plant with bagging experiments and test of apomixis. B. subacaulis grows in habitats with low pollination services; it is self-compatible, but many typical features favouring cross-pollination are still present: florets are characterized by incomplete protandry, capitulum protogyny and high pollen-ovule ratio. The plant is not apomictic and self-fertilization is allowed within each capitulum. Similarly to other European Alpine endemics supposed to belong to the Mediterranean ancient tropical flora, the reproductive mode observed in the monospecific genus Berardia assured reproduction also under a pollinator decline. Differently from the other endemics, it took advantage of its spontaneous self-pollination and compatibility and its generalist pollination service, common both among high altitude plants and in the Asteraceae.
... The species is a perennial rosette herb and grows in damp, shady, calcareous rock crevices at altitudes of 150-1950 m (Strid 1991;Szelag and Somlyay 2009;Petrova and Vladimirov 2010). Its flower morphology suggests entomophily, similar to other European Gesneriaceae such as R. myconi and J. heldreichii (Vokou et al. 1990;Dubreuil et al. 2008), though they are seemingly not visited frequently by honeybees or bumblebees (Kozuharova 2008;Bogacheva-Milkoteva et al. 2013). It has been described as a resurrection plant long ago (Ganchev 1950) and was extensively studied in this respect (e.g., Djilianov et al. 2011 and references therein). ...
... The distribution of genetic diversity depends on several factors, such as gene flow, genetic drift, breeding system, seed dispersal ability, and geographic distribution range (Hogbin and Peakall 1999). Haberlea is entomophilous (Fritsch 1893(Fritsch -1894Kozuharova 2008;Bogacheva-Milkoteva et al. 2013), and its seeds have no obvious morphological traits favoring long-distance dispersal (Beaufort-Murphy 1983, pl. 15F). ...
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Premise of research. Even though the Balkan Peninsula is a biodiversity hot spot in southeastern Europe harboring many endemic plants, very little is known about the temporal extent of the phylogeographic history and the contemporary genetic diversity of the endemics there. Haberlea rhodopensis is one of the European Gesneriaceae species occurring in this region and represents appropriate study material to address these questions. Methodology. We generated fossil-dated molecular phylogenies (atpB-rbcL, trnH-psbA, trnLF, ITS) across the Lamiales to determine the origin and age of H. rhodopensis and conducted phylogeographic (trnH-psbA, ITS) and population genetic (ISSRs) analyses on 17 populations from Bulgaria and Greece, covering the entire distribution range of the species, to investigate their biogeographic history, present-day genetic diversity, and differentiation levels. Pivotal results. The European Gesneriaceae genera have a Tertiary origin in the early Oligocene, while the Haberlea lineage emerged in the late Oligocene. Extinctions appear to have marked the history of the genus for a long period of time, and the extant populations diverged in the late Pleistocene. A significant differentiation was apparent between populations from Bulgaria, that is, the Balkan Mountains in the north and the Bulgarian side of the Rhodopi massif in the south, but there was an even stronger differentiation between the latter and populations from Greece. This might be explained by the Rhodopi massif representing a barrier to gene flow, enforced during the Last Glacial Maximum, during which populations descended on opposing north- and south-facing mountain slopes. Conclusions. Haberlea represents an ancient lineage with recent diversification. The extant populations are of recent origin and indicate glacial refugial areas in Bulgaria and Greece. This study sheds light on historic and current phylogenetic and phylogeographic events that shaped the flora of the Balkan Peninsula, an area that has long been recognized for its species diversity and richness. Our data suggest that it may have acted as a persistent refugial area in southeast Europe since the mid-Tertiary.
... The plant flowers in May-June, when normally it is collected. It has been found that the flowers have low nectar content and weak floral scent, therefore the herb is not attractive for honeybees (Bogacheva-Milkoteva et al., 2013). ...
Ethnopharmacological relevance: Haberlea rhodopensis (HR) use dates back to the Thracian and Roman periods. Bulgarians call it Orpheus flower and exploit its leaves for making tea and extracts with detoxifying, tonic, restorative and rejuvenating effects. HR was traditionally applied in wound healing and treatment of cattle diseases. Aim of the study: The general aim of the review was to analyze the progress of phytochemical and pharmacological studies on HR, focusing on its radioprotective and immunomodulating effects. Materials and methods: The main source material for the review was collected using several global search engines with the phrase: Haberlea rhodopensis, as well as Bulgarian books and dissertations. Results: HR metabolite profile includes large amounts of free sugars, polyols, polysaccharides (PS), flavonoids, phenolic acids and carotenoids. The radioprotective effect of 70% ethanolic leaf extract (70HREE) is explained by preservation of lymphocytes, other blood cells and testicular tissue from aberration under γ-radiation via stimulation of antioxidant enzymes and neutralization of free radicals. The extract immunomodulating activity results from raised antibody response, stem and neutrophil cell count, complement system activation, anti-tumour and anti-inflammatory effects. The detoxifying, restorative, rejuvenating and wound healing plant properties known to ethnomedicine were supported by radioprotective and immunomodulating studies. Conclusions: Metabolites of phenolic origin involved in HR resurrection are supposed to contribute to its radioprotective, immunomodulatory, anti-mutagenic and anti-aging effects. However, there is no chemical characterization of 70HREE in the investigations with humans and animals. Structure-activity relationship studies on HR immunomodulating and radioprotective compounds, and on their mode of action are required. They should include not only phenols but PS and other unexplored molecules. The metabolic activity of phagocytes, platelets and lymphocytes triggered by HR extracts has to be examined to elucidate their immunostimulatory potential. HR formulations can be tested in cosmetic, food and medical products as adjuvants to treat infectious, chronic inflammatory and tumour diseases, and especially in patients undergoing radiotherapy.
... This is in contrast with previous reports of "more intensive" vegetative reproduction in R. serbica (Velčev et al. 1973). Perhaps, With regard to the European representatives of Gesneriaceae, a few studies report pollination observations on J. heldreichii (Vokou et al. 1990), H. rhodopensis (Bogacheva-Milkoteva et al. 2013) and R. myconi (Picó and Riba 2002). ...
... Melittophilous (Apidae) flowers were purple, white, yellow, or orange, campanulate or funnelform, and zygomorphic or actinomorphic. Scattered reports of the observed pollinators in gesneriads displaying some combination of floral characters were also used to score the possible pollinator (Snow and Teixeira 1982;Steiner 1985;Feinsinger et al. 1986;Stiles and Freeman 1993;Kastinger and Weber 2000;SanMartin-Gajardo and Sazima 2004;2005a;2005b;Gao et al. 2006;Martén-Rodríguez and Fenster 2008;Tang et al. 2009;Camargo et al. 2011;Bogacheva-Milkoteva et al. 2013;Guo and Wang 2014;Rodrigues and Rodrigues 2014). Potential pollinators in different geographic regions were considered if that pollinator was native or naturalized to a specific region where the gesneriad species occurred. ...
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Using a time-calibrated phylogenetic hypothesis including 768 Gesneriaceae species (out of ~ 3300 species) and more than 29,000 aligned bases from 26 gene regions, we test Gesneriaceae for diversification rate shifts and the possible proximal drivers of these shifts: geographic distributions, growth forms, and pollination syndromes. Bayesian Analysis of Macroevolutionary Mixtures analyses found five significant rate shifts in Beslerieae, core Nematanthus , core Columneinae, core Streptocarpus , and Pacific Cyrtandra . These rate shifts correspond with shifts in diversification rates, as inferred by Binary State Speciation and Extinction Model and Geographic State Speciation and Extinction model, associated with hummingbird pollination, epiphytism, unifoliate growth, and geographic area. Our results suggest that diversification processes are extremely variable across Gesneriaceae clades with different combinations of characters influencing diversification rates in different clades. Diversification patterns between New and Old World lineages show dramatic differences, suggesting that the processes of diversification in Gesneriaceae are very different in these two geographic regions.
Most people are aware that pollinators are in trouble, and with them agricultural products worth more than $200 billion annually (FAO. Pollinators vital to our food supply under threat., 2017). Pollinators are fundamental to maintaining both biodiversity and agricultural productivity, but habitat destruction, loss of flower resources, and increased use of pesticides (particularly neonicotinoids) are causing declines in their abundance and diversity.
This is a pre-print of an article that is now In Press in American Journal of Botany
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The architectural complexity of flower structures (hereafter referred to as floral complexity) may be linked to pollination by specialized pollinators that can increase the probability of successful seed set. As plant-pollinator systems become fragile, a loss of such specialized pollinators could presumably result in an increased likelihood of pollination failure. This is an issue likely to be particularly evident in plants that are currently rare. Using a novel index describing floral complexity we explored whether this aspect of the structure of flowers could be used to predict vulnerability of plant species to extinction. To do this we defined plant vulnerability using the Red Data Book of Rare and Threatened Plants of Greece, a Mediterranean biodiversity hotspot. We also tested whether other intrinsic (e.g. life form, asexual reproduction) or extrinsic (e.g. habitat, altitude, range-restrictedness) factors could affect plant vulnerability. We found that plants with high floral complexity scores were significantly more likely to be vulnerable to extinction. Among all the floral complexity components only floral symmetry was found to have a significant effect, with radial-flower plants appearing to be less vulnerable. Life form was also a predictor of vulnerability, with woody perennial plants having significantly lower risk of extinction. Among the extrinsic factors, both habitat and maximum range were significantly associated with plant vulnerability (coastal plants and narrow-ranged plants are more likely to face higher risk). Although extrinsic and in particular anthropogenic factors determine plant extinction risk, intrinsic traits can indicate a plant's proneness to vulnerability. This raises the potential threat of declining global pollinator diversity interacting with floral complexity to increase the vulnerability of individual plant species. There is potential scope for using plant-pollinator specializations to identify plant species particularly at risk and so target conservation efforts towards them.
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One view of pollination systems is that they tend toward specialization. This view is implicit in many discussions of angiosperm evolution and plant-pollinator coevolution and in the long-standing concept of "pollination syndromes." But actual pollination systems often are more generalized and dynamic than these traditions might suggest, To illustrate the range of specialization and generalization in pollinators' use of plants and vice versa, we draw on studies of two floras in the United States, and of members of several plant families and solitary bee genera, We also summarize a recent study of one local flora which suggests that, although the colors of flowers are aggregated in "phenotype space," there is no strong association with pollinator types as pollination syndromes would predict. That moderate to substantial generalization often occurs is not surprising on theoretical grounds. Plant generalization is predicted by a simple model as long as temporal and spatial variance in pollinator quality is appreciable, different pollinator species do not fluctuate in unison, and they are similar in their pollination effectiveness. Pollinator generalization is predicted when floral rewards are similar across plant species, travel is costly, constraints of behavior acid morphology are minor, and/or pollinator lifespan is long relative to flowering of individual plant species. Recognizing that pollination systems often are generalized has important implications. In ecological predictions of plant reproductive success and population dynamics it is useful to widen the focus beyond flower visitors within the "correct" pollination syndrome, and to recognize temporal and spatial fluidity of interactions. Behavioral studies of pollinator foraging choices and information-processing abilities will benefit from understanding the selective advantages of generalization. In studies of floral adaptation, microevolution, and plant speciation one should recognize that selection and gene flow vary in time and space and that the contribution of pollinators to reproductive isolation of plant species may be overstated. In conservation biology, generalized pollination systems imply resilience to linked extinctions, but also the possibility for introduced generalists to displace natives with a net loss of diversity.
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The structure of species interaction networks is important for species coexistence, community stability and exposure of species to extinctions. Two widespread structures in ecological networks are modularity, i.e. weakly connected subgroups of species that are internally highly interlinked, and nestedness, i.e. specialist species that interact with a subset of those species with which generalist species also interact. Modularity and nestedness are often interpreted as evolutionary ecological structures that may have relevance for community persistence and resilience against perturbations, such as climate-change. Therefore, historical climatic fluctuations could influence modularity and nestedness, but this possibility remains untested. This lack of research is in sharp contrast to the considerable efforts to disentangle the role of historical climate-change and contemporary climate on species distributions, richness and community composition patterns. Here, we use a global database of pollination networks to show that historical climate-change is at least as important as contemporary climate in shaping modularity and nestedness of pollination networks. Specifically, on the mainland we found a relatively strong negative association between Quaternary climate-change and modularity, whereas nestedness was most prominent in areas having experienced high Quaternary climate-change. On islands, Quaternary climate-change had weak effects on modularity and no effects on nestedness. Hence, for both modularity and nestedness, historical climate-change has left imprints on the network structure of mainland communities, but had comparably little effect on island communities. Our findings highlight a need to integrate historical climate fluctuations into eco-evolutionary hypotheses of network structures, such as modularity and nestedness, and then test these against empirical data. We propose that historical climate-change may have left imprints in the structural organisation of species interactions in an array of systems important for maintaining biological diversity.
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The once prevalent view that the evolution of extreme ecological specialization is accompanied by a loss of potential for adapting to new conditions, and thus is irreversible, has been challenged by several recent examples,,. However, we know of no modern phylogenetic studies showing reversal in pollination relationships from extreme specialization to generalization, although such reversals are theoretically expected,. Here we present molecular phylogenetic evidence for an evolutionary shift in Dalechampia (Euphorbiaceae) vines from a highly specialized relationship (pollination by one or a few animal species,) with resin-collecting bees to generalized pollination by a variety of pollen-feeding insects. This shift was associated with dispersal from Africa to Madagascar, where the specific resin-collecting pollinators are absent. These results show that plants dispersing beyond the range of their specific pollinators may succeed by evolving more generalized pollination systems.
Jankaea heldreichii, a monotypic species of the Gloxinia family and a Tertiary relict, is restricted only to Mt Olympus (Greece). Its phenology of flowering, breeding system, mode of pollination, and reproductive potential were studied. Results showed that, although confined to a small area, this important plant species is not at present seriously endangered. Its vulnerability depends mostly on tourist pressure and uncontrolled collection.
The phylogenetic placement of the Old World Gesneriaceae genera Ramonda, Conandron, Bournea, Thamnocharis, and Tengia, all characterized by actinomorphic flowers, has been the subject of much debate. Actinomorphy in Gesneriaceae is rare, with most species exhibiting zygomorphic flowers. The actinomorphic genera have historically been considered “primitive“ and lumped in the tribe Ramondeae separate from the remaining Old World Gesneriaceae. In this study, we used nuclear (ITS) and plastid (trnL-F) DNA for molecular phylogenetic analysis of these five genera along with representative species across the Cyrtandroideae. Our results show that the actinomorphic genera are scattered over several otherwise zygomorphic clades within Cyrtandroideae, and along with previous data, indicate that Ramondeae is an unnatural group. Floral actinomorphy has evolved convergently in different alliances of Old World Gesneriaceae. Ramonda is sister to Haberlea, Bournea is apparently paraphyletic, Conandron seems rather isolated, and Tengia is close to Petrocodon and sister to a group of Chirita sect. Gibbosaccus together with Calcareoboea. We hypothesize that the evolution from zygomorphy to actinomorphy with novel combinations of characters is possibly due to shifts in pollination strategies, such as a switch from nectar- to pollen-rewards.