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Rediscovery of the mistletoe Bakerella hoyifolia subsp. bojeri (Loranthaceae) on Reunion Island: population status assessment for its conservation

  • Conservatoire Botanique National de Mascarin, La Réunion, France

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The mistletoe Bakerella hoyifolia subsp. bojeri (Baker) Balle was presumed extinct from Reunion Island, where it is native, for over 50 years. We recently found B. hoyifolia plants in a well-preserved forest stand in the southeastern part of the island. The small population consists of six individuals, distributed in two groups, ca. 50 m apart, growing on five host plant species from different families, suggesting a low host specificity. Each group is structured vertically with a large mistletoe established on an emerging tree while smaller mistletoes are seen on the trees below. Moreover, we observed the Reunion grey white-eye, Zosterops borbonicus (J. R. Forster, 1781) visiting flowers of these mistletoes found on Reunion. Further investigations are required in order to clarify the genetic isolation and taxonomic position of this population relative to those in Mauritius and Madagascar, and the mechanisms that have caused its decline on Reunion. Two possible mechanisms are discussed. The loss of most frugivorous vertebrates on Reunion Island soon after human settlement, may have driven this mistletoe to extinction. Among rapid conservation actions, propagation from seeds should be carried out in order to prevent the extinction of this native plant population.
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Botany Letters
ISSN: 2381-8107 (Print) 2381-8115 (Online) Journal homepage:
Rediscovery of the mistletoe Bakerella hoyifolia
subsp. bojeri (Loranthaceae) on Reunion Island:
population status assessment for its conservation
S. Albert, A. Rhumeur, J. L. Rivière, A. Chauvrat, S. Sauroy-Toucouère, F.
Martos & D. Strasberg
To cite this article: S. Albert, A. Rhumeur, J. L. Rivière, A. Chauvrat, S. Sauroy-Toucouère,
F. Martos & D. Strasberg (2017): Rediscovery of the mistletoe Bakerella hoyifolia subsp. bojeri
(Loranthaceae) on Reunion Island: population status assessment for its conservation, Botany
Letters, DOI: 10.1080/23818107.2017.1340191
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Published online: 12 Jul 2017.
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Mistletoe; Loranthaceae;
Bakerella; seed dispersal;
bird pollination; Island
conservation; Mascarene
Islands; extinction
Received 23 March 2017
Accepted6 June 2017
© 2017 Société botanique de France
Rediscovery of the mistletoe Bakerella hoyifolia subsp. bojeri (Loranthaceae) on
Reunion Island: population status assessment for its conservation
S. Alberta, A. Rhumeurb, J. L. Rivièrec, A. Chauvratd, S. Sauroy-Toucouèrea, F. Martose and D. Strasberga
aUniversité de La Réunion, UMR PVBMT, Saint-Denis, France; bConservatoire Botanique National de Mascarin, Saint-Leu, France; cSaint-Denis,
France; dSaint-Leu, France; eCIRAD, UMR PVBMT, Saint-Pierre, France
The mistletoe Bakerella hoyifolia subsp. bojeri (Baker) Balle was presumed extinct from Reunion
Island, where it is native, for over 50years. We recently found B. hoyifolia plants in a well-
preserved forest stand in the southeastern part of the island. The small population consists of
six individuals, distributed in two groups, ca. 50m apart, growing on ve host plant species
from dierent families, suggesting a low host specicity. Each group is structured vertically
with a large mistletoe established on an emerging tree while smaller mistletoes are seen on
the trees below. Moreover, we observed the Reunion grey white-eye, Zosterops borbonicus (J.
R. Forster, 1781) visiting owers of these mistletoes found on Reunion. Further investigations
are required in order to clarify the genetic isolation and taxonomic position of this population
relative to those in Mauritius and Madagascar, and the mechanisms that have caused its decline
on Reunion. Two possible mechanisms are discussed. The loss of most frugivorous vertebrates
on Reunion Island soon after human settlement, may have driven this mistletoe to extinction.
Among rapid conservation actions, propagation from seeds should be carried out in order to
prevent the extinction of this native plant population.
Bakerella Tiegh. is a genus in the family Loranthaceae,
which comprises 16 species of hemiparasitic plants.
ese plants are photosynthetic but obtain all water
and minerals from their host plant, onto which they
form haustoria (Heide-Jørgensen 2008). Bakerella is
endemic to the Western Indian Ocean Islands, with
species found in Madagascar, the Comoros, Seychelles
and Mascarene islands. From a taxonomic perspec-
tive, the genus was revised by Balle (1964a). is
author recognized three subspecies within the species
B. hoyifolia that shows a wide distribution among the
Western Indian Ocean islands: B. hoyifolia (Baker) Balle
subsp. hoyifolia, B. hoyifolia (Baker) Balle subsp. boïnensis
Balle (both endemic to Madagascar), and B. hoyifolia
(Baker) Balle subsp. bojeri (Baker) Balle (endemic to
Mauritius and Reunion). e latter is the only mem-
ber of the Loranthaceae on the Mascarene archipelago.
While B. hoyifolia subsp. bojeri is an endangered plant in
Mauritius (Atkinson and Sevathian 2005), it is presumed
extinct on Reunion (Fontaine and Lavergne 2010; Staub
1988). According to the rst red list established for native
plants that are threatened on Reunion, B. hoyifolia subsp.
bojeri should be the object of conservation actions and
eld prospection priorities (Dupont, Girard, and Guinet
Bakerella hoyifolia subsp. bojeri was rst collected on
Reunion by Commerson in 1770 in Saint-Joseph (see
collection P04956421, MNHN, Paris) (Figure 1(A)).
Frappier then collected several specimens between
1853 and 1863, including the collection Frappier no. 985
(P04956424, MNHN, Paris), but unfortunately did not
specify the exact geographical origin of his collection.
According to Jacob de Cordemoy (1895), this mistle-
toe was rare at the end of the nineteenth century, but
was previously common on the windward and leeward
sides of the island, where he had collected several sam-
ples. According to Cadet (1984), Rivals collected this
mistletoe in the highlands of Saint-Paul in the 1950s.
erefore, B. hoyifolia subsp. bojeri would have been
common on Reunion, in rain forest habitat at any ele-
vations. Similarly, B. hoyifolia subsp. hoyifolia is found
from the lowest rainforests to the treeline in Madagascar
(Balle 1964b).
e conservation status of B. hoyifolia subsp. bojeri on
Reunion in contrast to Mauritius is puzzling. It has been
so rarely observed on Reunion over the past century that
its common name, le gluet (Audouin et al. 1825; Cuvier
1821; Lamarck and Poiret 1811) has been forgotten
there. Reunion Island still has 30% of its native habitats
(Strasberg et al. 2005), some of which are well preserved
and protected in a national park. e protected areas
are classied as a UNESCO World Heritage Site. In
comparison, less than 5% of native habitats remain in
Mauritius, which moreover are highly fragmented and
highly invaded by alien plants (Florens 2013; Florens
etal. 2012). In Mauritius, B. hoyifolia subsp. bojeri, which
is locally called Bois er, undergoes overharvesting since
it is used as a medicinal plant (Rouillard and Guého
1999; Tatayah 2011). e same kind of use and threat
has been reported in closely related species from the
Seychelles, B.clavata (Desr.) Balle (Friedmann 1994).
e rapid transformation of native habitats is certainly
the main driver of biodiversity loss on oceanic islands
(Caujapé-Castells et al. 2010). However, it alone can
hardly explain why B. hoyifolia subsp. bojeri has gone
extinct on Reunion but not in Mauritius.
e reproductive biology of B. hoyifolia subsp. bojeri
is poorly documented. e brightly colored owers
with long corolla tubes in B. hoyifolia must be bird
pollinated, as are all Afro-Asiatic Loranthaceae (Vidal-
Russell and Nickrent 2008). According to Staub (1988)
and Gill (1971), the owers of B. hoyifolia subsp. bojeri
in Mauritius are visited by white-eyes (Zosteropidae).
e fruits of B. hoyifolia must be zoochorous, as are all
mistletoe species, and the seeds must be dispersed to
establish on a likely tree (Benzing 2012). e dispersal
strategies have been widely studied among mistletoes
(McKey 1975; Watson 2001), but not in the species
that occur in the Western Indian Ocean Islands with
no frugivorous specialist (Watson and Rawsthorne
2013). In Madagascar, Bakerella fruits are highly val-
ued by lemurs (Atsalis 1999; Hemingway 1998), ying
foxes (Bollen and Van Elsacker 2002), and various birds
(Bollen 2003; Razandratsita 1995). In Mauritius, the
fruit of B. hoyifolia subsp. bojeri is apparently attractive
to birds (Staub 1988) and bats (von Bethlenfalvy 2006).
However, a breakdown of mutualistic interactions on
Reunion could explain the early decline of B. hoyifolia
subsp. bojeri on this island. is was shown, for instance,
in the pollination (Murphy and Kelly 2001; Robertson
et al. 1999) and seed dispersal (Ladley and Kelly 1996)
of some mistletoe species in New Zealand.
In this paper, we report the discovery of a small pop-
ulation of B. hoyifolia on Reunion. We rst illustrate and
discuss the morphology of the rediscovered mistletoe
relative to the descriptions of B. hoyifolia subsp. bojeri by
Philcox (1982) and Balle (1964a). We then describe the
main ecological characteristics of this population, and
its forest habitat and host specicity. Finally, we discuss
potential mechanisms that could account for the dra-
matic decline of B. hoyifolia subsp. bojeri on Reunion.
is eld study was conducted at Vallée Heureuse, in
the area of Saint-Philippe, between December 2016 and
March 2017 (Figure 1(B)). Given the conservation status
of B. hoyifolia on Reunion, we will not communicate the
GPS coordinates of the mistletoe population in this area.
Our morphological description of B. hoyifolia subsp.
bojeri was entirely based on photos taken in the eld, and
no specimens were collected during this study. Photos
were taken with an EF 70–200mm f/2.8L mounted on
a Canon EOS 7D Mark II. To monitor visitors of owers
and fruits, we also used a Bushnell Trophy Cam HD.
is digital video camera was set to operate during the
day and night with a movement trigger, and put up in
the forest understory at ca. two meters from owers and
fruits over a period of four months.
Description of B. hoyifolia subsp. bojeri at Vallée
e mistletoe population, which was found at Vallée
Heureuse in December 2006, consists of six individu-
als. e largest mistletoe is around 1m high and has a
large number of stems (Figure 2(A)). B. hoyifolia subsp.
bojeri can grow on layering branches of small diameter,
or directly on the trunk, even when it exceeds 20cm in
diameter. e main sucker causes a globular swelling, and
the stem emits a series of regularly distributed second-
ary suckers (Figure 2(B)). e globular swelling reaches
around 10cm in diameter. e twigs have lenticels, and
the leaves are generally opposite or sometimes subopposite
(Figure 2(C)). e leaves are distinctly petiolate, and the
blade is entire with a secondary basal eucamptodromous
nerve (Figure 2(D)). e blade is highly variable in shape
and size depending on twigs and shrubs (Figure 2(E)).
e plant is cauliorous, and the inorescence is a (2)
3–5 ower fascicle. e ower buds are more or less clav-
iform, red to pinkish (Figure 3(A)). e calyx shows ve
short lobes (Figure 3(B)). e corolla is arched, red to
pinkish, with ve reexed white lobes (Figure 3(C)); it is
Figure 1. (A) Historical record of Bakerella hoyifolia subsp. bojeri
on Reunion Island by naturalists (a. Commerson, b: d. Jacob de
Cordemoy, e. Rivals) (white crosses). (B) Rediscovery record of
B. h. subsp. bojeri at Vallée Heureuse on the slopes of the Piton
de La Fournaise volcano. For both maps, the area of the Parc
national de La Réunion which covers around 30% of the island
is shown.
23–26mm long and deciduous (Figure 3(D)). Fruiting is
particularly abundant, with ca. 400 fruits on a few twigs
on the largest mistletoe (Figure3(E)). e fruit is bacci-
form, pedicellate, obovoid, ca. 10–12mm (Figure3(F)).
It generally carries an accrescent calyx and a persistent
(sub-) unilateral bract (Figure3(G)). e fruits observed at
Vallée Heureuse are all green colored, and no color change
was observed between December 2016 and March 2017.
Forest habitat and host trees
Bakerella hoyifolia subsp. bojeri was rediscovered at
around 1000 m in submontane windward rainfor-
est, according to Dupouey and Cadet (1986). is
forest habitat was studied in the 1970s by the French
botanist T. Cadet, who recorded in an 800m² plot 48
woody species, half of which are endemic to Reunion
(unpublished data). e canopy structure is irregular,
with trees rarely exceeding 15m but reaching diame-
ters at breast height of 1m. e canopy is composed of
native plant species only, and the forest understory is
barely disturbed, with very few exotic invasive plants.
Five of the six native forest songbirds were observed in
the studied area, including both species of white-eyes,
Zosterops olivaceus (Linnaeus, 1766) and Z. borbonicus
(J. R. Forster, 1781), and the Reunion Bulbul, Hypsipetes
borbonicus (J. R. Forster, 1781), despite some poaching
evidence in the area.
e small population of B. hoyifolia subsp. bojeri
includes two groups 50 m apart (Table 1). In each
group, larger mistletoes growing on emerging trees
are well visible, and others were observed on smaller
neighboring trees. e host trees in this population of
B. hoyifolia subsp. bojeri are all common and endemic to
the Mascarenes, except Aphloia theiformis (Vahl) Benn.
(Aphloiaceae), which is also found in Madagascar and
East Africa.
Phenology and ower visitors
Flowering was observed in February and March 2017
and was massive in the canopy plants. e fact that some
ower buds were observed in March suggests that ow-
ering may still occur in April. In March, we observed the
Reunion grey white-eye, Zosterops borbonicus, on owers
of B. hoyifolia subsp. bojeri in the tree canopy (Figure 4).
Figure 2. Bakerella hoyifolia subsp. bojeri, vegetative features. (A) Large mistletoe with large haustorium (arrow) on Homalium
paniculatum. (B) Haustoria structure on Weinmannia tinctoria. (C) Opposite leaves. (D) Basal eucamptodromous secondary nervation.
(E) Narrow limb. Photos. J. L. Rivière.
Taxonomic revision of the various subspecies of
e mistletoes found at Vallée Heureuse overall conform
to the description of B. hoyifolia in Balle (1964b). Based
on their geographic origin (i.e. Reunion), we assume
that these plants belong to the subspecies bojeri. Since
there is no key to the various subspecies of B. hoyifolia,
During one hour of observation, birds of what could be
the same species were visiting the owers. We observed
two plumage color variants of Z. borbonicus in the popu-
lation (Cornuault et al. 2015). At the very end of March,
we were also able to observe interactions between the
Reunion grey white-eye and owers of B.hoyifolia subsp.
bojeri in the forest understory (photos not presented).
To date, we have not detected any interaction with the
fruits using the Bushnell video camera.
Figure 3.Bakerella hoyifolia subsp. bojeri, reproductive features. (A) Flower buds more or less claviform on naked twigs. (B) Calyx with
short lobes (arrows). (C) Arched corolla with 5 reflexed white lobes. (D) Deciduous corolla. (E) Massive fructification (red arrows) on
the canopy. (F) Bacciform fruits carrying an accrescent calyx. (G) Persistent unilateral bract. Photos. J. L. Rivière.
Table 1.Characteristics of the two groups including the six mistletoes discovered at Vallée Heureuse. For each mistletoe, the height
to which it grew and the taxonomy of the host are given.
Group Mistletoe Height (m) Host species Host family
1 1 11 Homalium paniculatum (Lam.)
1 2 6 Monimia ovalifolia Thouars Monimiaceae
1 3 4 Weinmannia tinctoria Sm. Cunoniaceae
2 4 9 Weinmannia tinctoria Sm. Cunoniaceae
2 5 6 Molinaea alternifolia Willd. Sapindaceae
2 6 6 Aphloia theiformis (Vahl) Benn. Aphloiaceae
A very rare plant despite low host specicity
Although numerous vegetation surveys have taken place
on Reunion since the 1970s, starting with the French bot-
anist T. Cadet, it is striking that this mistletoe species has
not been seen again for such a long time. According to
Staub (1988), it is quite dicult to distinguish B. hoyifolia
subsp. bojeri from its host when it is not owering, but the
bright pink corollas are highly visible, especially on the
forest oor. is is why we think that the probability of
detecting other populations on Reunion Island is very low.
B. hoyifolia subsp. bojeri shows a low host specicity
on Reunion. e host trees at Vallée Heureuse belong
to the Rosids (e.g. Oxalidales, Malpighiales, Sapindales)
and to the Magnoliids (e.g. Laurales). is low host spec-
icity has already been reported by Philcox (1982) and
Staub (1988) in Mauritius. According to these authors,
B. hoyifolia subsp. bojeri can grow on the Asterids (e.g.
Asterales, Ericales) and the Rosids (e.g. Malpighiales,
Myrtales) in Mauritius. Similarly, Balle (1964b) reported
host trees belonging to the Asterids (e.g. Ericales,
Gentianales) and the Rosids (e.g. Malvales, Malpighiales,
Myrtales) for B. hoyifolia in Madagascar.
Habitat loss alone fails to explain the rapid decline of
B. hoyifolia subsp. bojeri on Reunion. Indeed, we know
from historical records that this mistletoe species was
able to colonize rainforest habitats that are still well
represented on Reunion Island (Strasberg et al. 2005).
Moreover, the ve host species at Vallée Heureuse are
common and have a wide elevational range on the island.
In Mauritius, which has been le with less than 5% of its
native forest area (Florens et al. 2012), large populations
of B. hoyifolia subsp. bojeri persist to date, sometimes in
highly disturbed environments (Staub 1988). However,
native vertebrates, especially the frugivorous, are more
diverse in Mauritius than in Reunion (Cheke 1987). We
suggest that disruption of the mutualistic interactions
must have occurred on Reunion following the extinction
of the vertebrate fauna.
it is dicult to distinguish B. hoyifolia subsp. bojeri
from the Mascarenes and B. hoyifolia subsp. hoyifolia
from Madagascar on the basis of their morphology.
According to Philcox (1982), three oral characters
should be useful to distinguish B. hoyifolia subsp. bojeri
from its Madagascan relatives: smaller and less dened
calyx lobes; distinctly claviform ower buds; and less
arched corolla tube. If the calyx conforms to Philcox’s
description, the buds are not so distinctly claviform
compared to those of B. hoyifolia subsp. hoyifolia, and
the corollas of the plants at Vallée Heureuse are distinctly
arched. Moreover, the ripe fruit color is probably green
(von Bethlenfalvy 2006; Bollen and Van Elsacker 2002)
and can turn yellow, according to Staub (1988). ese
observations, as well as our own, are incongruent with
the dark brown coloration of ripe fruits described by
Balle (1964b) and Philcox (1982). Indeed, these latter
descriptions were based on dry material.
No indication is given in the Flore des Mascareignes
(Philcox 1982) about the habit and the overall dimen-
sions of B. hoyifolia. e mistletoes growing at Vallée
Heureuse have an erect habit reaching ca. 1m. It is also
this ability to throne on its hosts above the canopy that
earned these plants the name Bois er in Mauritius (Staub
1988). ey are able to grow in a vegetative manner by
forming secondary haustoria on their hosts (Balle 1964a).
We still do not know whether these mistletoes can grow
on dierent plant species at the same time, as is the case
for the Madagascan species Bakerella grisea (Scott-Elliot)
Balle, which can reach 20m long (Balle 1964a).
As per Mathiasen and Kenaley (2016), we believe
that the taxonomic status of the various subspecies of
B. hoyifolia is uncertain. Genetic characterization of
the various forms observed on Reunion, Mauritius and
Madagascar would be highly valuable to the taxonomy of
Bakerella. In this view, a concerted eort between ourselves,
the Mauritius Herbarium, and Missouri Botanical Garden
in Madagascar, would be helpful to obtain plant specimens
and DNA material from Mauritius and Madagascar.
Figure 4.Zosterops borbonicus visiting flowers of Bakerella hoyifolia subsp. bojeri on the canopy. Photos. J. L. Rivière.
Oceanic islands usually have a high proportion of endan-
gered plant taxa, most of which are endemic. Floristic
surveys are never in vain and must be sustained in an
age of ecological restoration. We propose to switch
B.hoyifolia subsp. bojeri from the IUCN category “data
decient” to “critically endangered.” A genetic study
should be conducted in order to understand the taxon-
omy of Bakerella in its native area. Field experiments in
Mauritius and Reunion would also be helpful to resolve
the breeding system of B. hoyifolia subsp. bojeri and to
identify animals that achieve dispersal of the seeds. is
would allow us to disentangle the role of birds and ying
foxes as pollinators and/or seed dispersers. e most
urgent goal, however, is to launch a propagation pro-
gram. Such a project would be an exciting challenge for
conservationists on Reunion.
We are grateful to the Parc national de La Réunion for pro-
viding us with GIS layers. We would also like to thank N.
Wilding and M. Rouget for their critical assessment of this
manuscript, as well as the editor and two reviewers.
Disclosure statement
No potential conict of interest was reported by the authors.
Notes on contributors
S. Albert MSc. degree student in ecology and evolution,
Université de La Réunion.
Contribution: rediscovered the species and wrote the paper.
A. Rhumeur botanist, Conservatoire Botanique National de
Contribution: co-rediscovered the species.
J. L. Rivière naturalist and photographer.
Contribution: co-rediscovered the species.
A. Chauvrat naturalist.
Contribution: co-rediscovered the species.
S. Sauroy-Toucouère MSc. degree student in ecology and
evolution, Université de La Réunion.
Contribution: co-rediscovered the species.
F. Martos researcher, Peuplements Végétaux et Bioagresseurs
en Milieu Tropical Joint Research Unit.
Contribution: co-wrote the paper.
D. Strasberg professor, Université de La Réunion.
Contribution: co-wrote the paper.
Atkinson, R., and J.-C. Sevathian. 2005. A Guide to the
Plants in Mauritius. Vacoas, Mauritius: Mauritian Wildlife
Mutualism disruption hypothesis
We show that the owers of B. hoyifolia subsp. bojeri
are visited by the Reunion grey white-eye Zosterops
borbonicus on Reunion, and we believe that they might
also be visited by the Reunion olive white-eye Zosterops
olivaceus (Gill 1971). ese two songbird species are cur-
rently not threatened on Reunion. ey are ecient polli-
nators of several woody plant species, such as the endemic
Trochetia granulata Cordem. (Malvaceae) (Le Le Péchon
et al. 2013), and they also pollinate some endemic orchids.
We are not aware of any study on the breeding system of a
Bakerella species. At Vallée Heureuse, we observed a very
high fruit set on most shoots. us, we suspect that these
plants are self- compatible, and that the fruit set should be
signicantly increased via geitonogamous pollination, as
shown in New Zealand species (Robertson et al. 1999).
e clustering of individuals at Vallée Heureuse may
be the result of a preferential perching of fruit consum-
ers on previously infected plants (Ward and Paton 2007).
However, we do not know whether this phenomenon
would occur in islands that lack frugivorous specialists
and where the behavior of frugivorous animals should be
more opportunistic. e clustering of individuals at Vallée
Heureuse may simply reect a strong constraint on disper-
sal. In Mauritius, Staub (1988) stated that the Mauritius
olive white-eye, Zosterops chloronothos (Vieillot, 1817)
ensures both dispersal by epizoochory and pollination
of B. hoyifolia subsp. bojeri. However, he did not discuss
the fact that this bird species was critically endangered
in Mauritius (Nichols, Woolaver, and Jones 2004), which
may result in a possible mutualism disruption (Ladley
and Kelly 1996; McConkey and O’Farrill 2016). Its sister
species, the Reunion olive white-eye Zosterops olivaceus,
mainly feeds on nectar and secondarily on insects and
some eshy fruits (Gill 1971). If Zosterops olivaceus
was the main disperser of B. hoyifolia subsp. bojeri on
Reunion, there should not exist any dispersal limitation
because this species is still widespread and abundant in
native habitats (Saord, Skerrett, and Hawkins 2015).
One possibility is that the fruit of B. hoyifolia subsp.
bojeri was mainly dispersed by birds and ying foxes
that are extinct on Reunion. Following this hypothesis,
the remaining birds may be facultative dispersers and
much less ecient. Lemurs, ying foxes, doves, parrots,
and songbirds have been observed to consume fruits of
Bakerella spp. in Madagascar (Atsalis 1999; Bollen and
Van Elsacker 2002; Bollen, Van Elsacker, and Ganzhorn
2003; Hemingway 1998). If lemurs were absent from
Pristine Reunion, ying foxes, doves, and parrots that
were important dispersers before the begining of the
human settlement disappeared between the seventeenth
and the nineteenth centuries (Cheke and Hume 2008).
e striking dierence between Reunion and Mauritius,
which still possesses ying foxes, doves, and parrots,
may explain why B. hoyifolia subsp. bojeri collapsed on
Reunion but not in Mauritius.
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... Habitat transformation and overharvesting by humans have been reported as major drivers of decline of some mistletoe species in the Mascarene Islands and Seychelles, while the near-extinction of Bakerella hoyifolia subsp. bojeri on Reunion was attributed to the loss of its hypothetically main dispersers (flying foxes, doves, and parrots) since human colonization of the island (Albert et al., 2017). Many species of African mistletoes are being studied by ethnobotanists due to their traditional use in spiritual practices as well as increasing exploitation in officinal medicine and by herbalists as "all-healing," "bone-setting," and "fertility-boosting" drugs (Koffi et al., 2020;Oriola et al., 2020). ...
... Following the last comprehensive assessment of host associations in African mistletoes by Polhill and Wiens (1998, 1999a, 1999b) and a number of regional studies (see Table S1 for the reference list), Grímsson et al. (2018) have recently compiled the continent-wide published host species records for the African Loranthaceae. In contrast, the island mistletoe taxa (from the Madagascar and neighboring islands) have remained virtually unaddressed in terms of host associations since Balle (1964aBalle ( , 1964b and Philcox (1982), except for occasional studies dealing with individual mistletoe taxa (Albert et al., 2017). Here, we discuss host diversity and patterns of host use in the African mainland and island mistletoes based on historical and recently published data supplemented with herbarium specimen records retrieved from various online databases and digitized herbarium specimens. ...
... endemic to Reunion and Mauritius, respectively, have been observed visiting the flowers of local Bakerella mistletoe species (Albert et al., 2017;Gill, 1971). Of other birds endemic to Madagascar, the Forest Fody (Foudia omiss, Ploceidae) and Velvet Asity (Philepitta castanea, Philepittidae) have also been observed as nectar feeders on Bakerella, and two species of Neodrepanis are known to suck nectar from the elongated flowers with their curved long beak (Craig, 2014;Raherilalao & Goodman, 2011;Rakotomanana & Rene de Roland, 2004). ...
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Mistletoes, as perennial hemiparasitic angiosperms that parasitize woody plants, are an important component of the highly diverse, endemically rich and mosaic African flora, which is attributed to the Holarctic, Paleotropical, and Cape Floristic kingdoms. The richness of African mistletoes from the Loranthaceae and Viscaceae, along with many aspects of their biology and ecology, was covered in the comprehensive monograph of Polhill and Wiens (1998, Mistletoes of Africa, Royal Botanic Gardens). The present review is devoted to the taxonomic and functional diversity of symbionts associated with mistletoes in Africa and adjacent islands that contribute to the major biological functions of mistletoes, such as establishment and growth, nutrition and fitness , resistance to external stresses, as well as pollination and dispersal. These functions are favored by more or less distinct sets of associated bionts, including host plants, animal herbivores, frugivorous birds, nectar-and pollen-feeding insects, and endophytic microorganisms. A separate section is devoted to mistletoe epiparasitism as a special case of host selection. All these organisms, which are components of the mistletoe-associated community and multitrophic network, define the role of mistle-toes as keystone species. Some aspects of the symbiont communities are compared here with patterns reported for mistletoes from other continents, particularly to identify potential relationships that remain to be explored for the African species. In addition , properties of endophytic mistletoe associates that contribute to the plant's communication with coexisting organisms are considered. We also highlight the important gaps of knowledge of the functioning of mistletoe-associated communities in Africa and indicate some applied issues that need future attention. Abstract in French is available with online material.
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Thousands of plant species worldwide are dependent on birds for pollination. While the ecology and evolution of interactions between specialist nectarivorous birds and the plants they pollinate is relatively well understood, very little is known on pollination by generalist birds. The flower characters of this pollination syndrome are clearly defined but the geographical distribution patterns, habitat preferences and ecological factors driving the evolution of generalist‐bird‐pollinated plant species have never been analysed. Herein I provide an overview, compare the distribution of character states for plants growing on continents with those occurring on oceanic islands and discuss the environmental factors driving the evolution of both groups. The ecological niches of generalist‐bird‐pollinated plant species differ: on continents these plants mainly occur in habitats with pronounced climatic seasonality whereas on islands generalist‐bird‐pollinated plant species mainly occur in evergreen forests. Further, on continents generalist‐bird‐pollinated plant species are mostly shrubs and other large woody species producing numerous flowers with a self‐incompatible reproductive system, while on islands they are mostly small shrubs producing fewer flowers and are self‐compatible. This difference in character states indicates that diverging ecological factors are likely to have driven the evolution of these groups: on continents, plants that evolved generalist bird pollination escape from pollinator groups that tend to maintain self‐pollination by installing feeding territories in single flowering trees or shrubs, such as social bees or specialist nectarivorous birds. This pattern is more pronounced in the New compared to the Old World. By contrast, on islands, plants evolved generalist bird pollination as an adaptation to birds as a reliable pollinator group, a pattern previously known from plants pollinated by specialist nectarivorous birds in tropical mountain ranges. Additionally, I discuss the evolutionary origins of bird pollination systems in comparison to systems involving specialist nectarivorous birds and reconstruct the bird pollination system of Hawaii, which may represent an intermediate between a specialist and generalist bird pollination system. I also discuss the interesting case of Australia, where it is difficult to distinguish between specialist and generalist bird pollination systems.
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The classification of Viscaceae in the second edition of the Jepson Manual (TJM2) differs radically from that in the first edition of the Jepson Manual (TJM1). The number of species of Arceuthobium M. Bieb. was reduced from 12 in TJM1 to three in TJM2, and for Phoradendron Nutt. reduced from seven species to four. The TJM2 treatment is conservative in regards to these taxa, and disregards many morphological, phenological, and other physiological discontinuities (e.g., host preferences) among the Viscaceae of California that have been consistently reported in the scientific literature since the 1960s. The species accepted in TJM2 have widespread geographical distributions containing distinct lineages, some of which we consider different species, and other lineages that may be considered cryptic taxa. These taxa are distinct enough, based on differences in morphology, phenology, host specificity, and geographic isolation, to warrant classification as species or subspecies. The taxonomic recognition...
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Detailed exploration of how the islands' steady invasion by humans and their escaped animals, with concomitant forest destruction, has caused the extinction of dozens of endemic species of bird, bats & reptiles since 1598, including the iconic dodo.
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Mauritius and Rodrigues are renowned for the unique biodiversity that evolved on these islands, and are conversely notorious for some of the highest global extinction records. Much of the extant plants and animals are seriously threatened, and programmes have attempted to restore biodiversity at both species and ecosystems levels. Plant and habitat restoration programmes have been motivated by biodiversity conservation solely and almost never for ethnobotanic reasons. However, up to 61 per cent of native and endemic plants used in species and habitat restoration have documented medicinal use. Therefore, the plant biodiversity conservation has the added advantage of saving native and endemic medicinal plants.
The late Navjot Sodhi conceived this book as a way of bringing to the forefront of our conservation planning for the tropics the views of people who were actually working and living there. In its 31 chapters, 55 authors present their views on the conservation problems they face and how they deal with them. Effective long term conservation in the tropics requires the full participation of local people, organizations and governments. The human population of tropical countries is expected to grow by more than 2.5 billion people over the next several decades, with expectations of increased consumption levels growing even more rapidly than population levels; clearly there will be a need for more trained conservationists and biologists. Significant levels of local involvement are essential to conservation success, with the rights of local people fully recognized, protected and fostered by governmental and international assistance. Overarching conservation plans are necessary, but cannot in themselves lead to success. The individual experiences presented in the pages of this book will provide useful models that may serve to build better and more sustainable lives for the people who live in the tropics and lead to the continued survival of as many species and functioning ecosystems as possible.
Parasitic flowering plants are of great general and scientific interest besides their economic importance when attacking crop plants. This beautifully illustrated book covers all parasitic families and most of the genera and discusses all main aspects of their biology. © 2008 by Koninklijke Brill NV, Leiden, The Netherlands, All rights reserved.
The dispersal, germination and establishment of the New Zealand Loranthaceae (Alepis flavida, Peraxilla colensoi, P. tetrapetala, Ileostylus micranthus and Tupeia antarctica) were investigated. The most important bird dispersers were tui, bellbirds and silvereyes. These birds appear to provide reasonably good quality dispersal: fruits were swallowed whole and the seeds later defecated in germinable condition; birds tended to visit plants for only 1-2 minutes and eat a few mistletoe fruits each time. Germinability of seeds ranged between species from moderate to high (17-96%). None of the study species of mistletoe germinated successfully unless the fruit skin (exocarp) was removed, by hand or by passage through a bird gut. While hand removal of the exocarp gave the same or higher percentage germination as bird removal, in the field bird dispersal is the only effective method of exocarp removal and is therefore essential. Dispersal was limiting at one of three sites studied (Craigieburn), suggesting that reductions in bellbird densities by introduced carnivores or competition for honeydew food sources may be indirectly affecting mistletoe reproduction. Establishment and survival of seedlings on host branches was low (15-28% depending on species to production of first independent leaves, 0-14% after two years). Survival of adults over one year of the study was 80% for Tupeia and 91-95% in the other species, showing that frequent establishment of seedlings is necessary for population maintenance. While disperser limitation does not seem to currently be a major threat to mistletoe survival, it must be considered as a possible factor both historically and in the future.