Molecular phylogenetics of the species-rich genus Habenaria (Orchidaceae) in the New World based on nuclear and plastid DNA sequences

Contrasting range changes of terrestrial orchids under future climate change in China

Climate change has impacted the distribution and abundance of numerous plant and animal species during the last century. Orchidaceae is one of the largest yet most threatened families of flowering plants. However, how the geographical distribution of orchids will respond to climate change is largely unknown. Habenaria and Calanthe are among the largest terrestrial orchid genera in China and around the world. In this paper, we modeled the potential distribution of eight Habenaria species and ten Calanthe species in China under the near-current period (1970-2000) and the future period (2081-2100) to test the following two hypotheses: 1) narrow-ranged species are more vulnerable to climate change than wide-ranged species; 2) niche overlap between species is positively correlated with their phylogenetic relatedness. Our results showed that most Habenaria species will expand their ranges, although the climatic space at the southern edge will be lost for most Habenaria species. In contrast, most Calanthe species will shrink their ranges dramatically. Contrasting range changes between Habenaria and Calanthe species may be explained by their differences in climate-adaptive traits such as underground storage organs and evergreen/deciduous habits. Habenaria species are predicted to generally shift northwards and to higher elevations in the future, while Calanthe species are predicted to shift westwards and to higher elevations. The mean niche overlap among Calanthe species was higher than that of Habenaria species. No significant relationship between niche overlap and phylogenetic distance was detected for both Habenaria and Calanthe species. Species range changes in the future was also not correlated with their near current range sizes for both Habenaria and Calanthe. The results of this study suggest that the current conservation status of both Habenaria and Calanthe species should be adjusted. Our study highlights the importance of considering climate-adaptive traits in understanding the responses of orchid taxa to future climate change.

Reproductive Isolation Among Three Nocturnal Moth-Pollinated Sympatric Habenaria Species (Orchidaceae)

Comparison and quantification of multiple pre- and post-pollination barriers to interspecific hybridization are important to understand the factors promoting reproductive isolation. Such isolating factors have been studied recently in many flowering plant species which seek after the general roles and relative strengths of different pre- and post-pollination barriers. In this study, we quantified six isolating factors (ecogeographic isolation, phenological isolation, pollinator isolation, pollinia-pistil interactions, fruit production, and seed development) that could possibly be acting as reproductive barriers at different stages among three sympatric Habenaria species (H. limprichtii, H. davidii, and H. delavayi). These three species overlap geographically but occupy different microhabitats varying in soil water content. They were isolated through pollinator interactions both ethologically (pollinator preference) and mechanically (pollinia attachment site), but to a variable degree for different species pairs. Interspecific crosses between H. limprichtii and H. davidii result in high fruit set, and embryo development suggested weak post-pollination barriers, whereas bidirectional crosses of H. delavayi with either of the other two species fail to produce fruits. Our results revealed that pollinators were the most important isolating barrier including both ethological and mechanical mechanisms, to maintain the boundaries among these three sympatric Habenaria species. Our study also highlights the importance of a combination of pre-and post-pollination barriers for species co-existence in Orchidaceae.

Contribution to the taxonomic revision of Brachycorythis-complex (Orchidaceae, Orchidoideae)

The aim of this paper is to present materials towards the taxonomic revision of Brachycorythis-complex (Orchidinae, Orchidaceae), which constitutes seven terrestrial genera and forty-eight species distributed in sub-Saharan Africa, Madagascar and SW Asia. The detailed morphological descriptions, together with distribution data and ecological preferences for particular taxa are provided. Artificial keys for taxa identification were prepared. A molecular timescale for Brachycorythis species on a background of the subtribe Orchidinae was reconstructed using nuclear and plastid molecular markers. The results show that representatives of Brachycorythis separated from its last common ancestor presumably ca 20 Mya and the youngest taxa within the group seem to be its Asiatic representatives.

Synopsis of Habenaria s.l. (Orchidaceae) in New Guinea and adjacent islands

A taxonomic synopsis of the orchid genus Habenaria in New Guinea and adjacent islands is presented. We confirmed the occurrence of 27 Habenaria species in study area. Sixteen of these are endemic and were not so far found outside New Guinea. Morphological characteristics and illustrations of floral segments of taxa are presented. One new species of Habenaria is described. Four neotypes are selected. An updated key to species groups and species occurring in the study area is provided. The importance of diagnostic floral characters in Habenaria is discussed.

Phylogeography of the neotropical epiphytic orchid, genus Dracula

The tropical Andes constitute a natural barrier between the Pacific Ocean and the Atlantic; in these mountains, are a great variety of Ecosystems, defined by factors such as orography, winds, humidity, temperature, among others. Some of these Ecosystems have different environmental conditions from tropical ones. In them, there is a great Biodiversity, in some cases endemic and associated with relatively small geographic areas. An example of this biodiversity is the orchids of the genus Dracula, about which discussions are currently generated due to the difficulty in classifying their members. The present work shows a study where DNA was isolated and sequenced from plant samples obtained from 52 species of orchids of the genus Dracula, which were analyzed using the MEGA7 software. Phylogenetic analysis of the DNA sequences showed a well-resolved topology that reflects a geographical pattern of several major clades of the Pacific and Atlantic watersheds. Geophysical conditions of the Andes have generated greater biodiversity of the genus Dracula on the side of the Pacific. Although the species Dracula cordobae and alessandroi reported on both sides of the study site belong to the same clade and show limited mobility through the drier area to the South of the mountain range.

Taxonomic revision of Habenaria josephi group (sect. Diphyllae s.l.) in the Pan-Himalaya

Species of the Habenaria josephi group in the Pan-Himalaya region are revised, based on their morphological characters and results of previous molecular phylogenetics. Eight distinctive species are recognised; key to the species, taxonomic descriptions, illustrations and distribution maps are provided. Habenaria josephi is re-instated, based on morphological and molecular evidence; H. wolongensis is synonymised with H. aitchisonii, a neotype for H. tibetica and the lectotypes for H. balfouriana, H. fargesii, H. glaucifolia and H. clarkei are designated.

Evidence for Middle Miocene origin and morphological evolutionary stasis in a Barbacenia Inselberg clade (Velloziaceae)

Atlantic Forest Inselbergs (AFI) and Campos Rupestres (CR) are mountains and highlands of eastern South America, relatively poorly studied and highly threatened, which display extraordinary levels of plant endemism and richness. In spite of their geographical and environmental differences, the origin of the flora of CR and AFI are likely linked to each other, because several plant clades are distributed across both ecosystems. In addition to these studies, little has been investigated about the historical biogeographical connections between AFI and CR and most evolutionary studies are restricted to CR. Barbacenia (Velloziaceae) is widely spread and nearly endemic to the AFI and CR outcrops and thus represent an ideal system to study the biogeographical connections between CR and AFI. Besides, given the remarkable diversity of Barbacenia in CR compared to AFI, it appears that different factors were important drivers in the diversification of Barbacenia lineages, likely leading to different patterns of morphological diversification. Here, we integrate phylogenetic, biogeographic and morphological approaches to: (i) address whether AFI species of Barbacenia are monophyletic and thus a single colonization of AFI can be inferred; (ii) understand the timing and geographical origin of CR and AFI clades; (iii) compare morphological diversity between Barbacenia from AFI and CR under the hypothesis that these two systems have experienced similar levels of morphological diversification during their evolutionary history. To this end, we presented a phylogeny inferred using plastid (atpB-rbcL, trnH-psbA and trnL-trnF) and nuclear (ITS) markers and a complete sampling of AFI Barbacenia, estimated divergence times, reconstructed the ancestral areas of Barbacenia clades and compared their morphological diversity based on a dataset of 16 characters. Our results provided evidence for a diversification of Barbacenia from the Middle Miocene to Pleistocene, as suggested in previous studies. We suggest that stepping-stone dispersal across mountaintops in interplay with paleovegetation dynamics during the global Miocene cooling and Pleistocene climatic oscillations may played an important role in the range expansion of modern AFI Barbacenia lineages. Finally, our results also showed a significant differences in morphological diversity between AFI and CR clades, suggesting a long-term morphological stasis in AFI species.

The pollination of Habenaria rhodocheila (Orchidaceae) in South China: When butterflies take sides

Habenaria is one of the largest terrestrial genera in the family Orchidaceae. Most field studies on Habenaria species with greenish-white and nocturnal scented flowers are pollinated by nocturnal hawkmoths and settling moths. However, H. rhodocheila presents reddish flowers lacking a detectable scent and fails to fit the moth pollination syndrome. We investigated the pollinators, breeding system, and functional traits of H. rhodocheila in South China and found that two diurnal swallowtail butterflies Papilio helenus and Papilio nephelus (Papilionidae) were the effective pollinators. When butterflies foraged for nectar in the spur, the pollinia became attached between the palpi. A triangular projected median rostellar lobe was found at the entrance (sinus) of the spur of H. rhodocheila. This lobe divided the spur opening into two entrances forcing butterflies to enter their proboscides through the left or right side. When the projection of median rostellar lobe was removed, the site of pollinium attachment changed to the eyes of the butterflies, leading to a higher rate of pollinium removal but lower rate of pollinium deposition. Our quartz glass cylinder choice experiment suggested that visual rather than olfactory cues provided the major stimuli for butterflies to locate these flowers. Hand pollination experiments suggested this species was self-compatible but pollinator-dependent. However, the proportion of seeds with large embryos produced in self-pollinated fruits was significantly lower than in cross-pollinated fruits, indicating a significant inbreeding depression. Unlike many other orchid species, fruit set was higher than rates of pollinium removal, indicating a high level of pollination efficiency in a species with friable pollinia. Shifts from moth to butterfly pollination in the genus Habenaria parallel other orchid lineages providing insights into the potential for pollinator-mediated floral trait selection.

Morphological and Genetic Diversities of Habenaria radiata (Orchidaceae) in the Kinki Area, Japan

Floral organs have evolved from leaves for reproduction, and the morphological analyses help to understand the plant diversity and evolution. Habenaria radiata (syn. Pecteilis radiata) is a terrestrial orchid living in wetlands in Japan, Russia, South Korea, and China. The habitats of this plant in Japan have been reduced because of environmental destruction and overexploitation, and thus it is on the Red List of Japan as a Near Threatened species. One of the three petals of the H. radiata flower is called a lip or labellum, which resembles a flying white bird, egret, or white heron, with its proposed function being to attract pollinators. To understand the diversity of H. radiata plants in different areas, we examined the lip morphology and phylogeny of populations from eight habitats in the Kinki area, Japan. The complex shapes of the lips were quantified and presented as a radar chart, enabling characterization of the morphological difference among populations. Phylogenetic analysis with microsatellite markers that we generated showed the variation of genetic diversity among populations, suggesting the different degrees of inbreeding, outbreeding, and vegetative propagation. Our approach offers a basic method to characterize the morphological and genetic diversity in natural populations.

Diel scent and nectar rhythms of an African orchid in relation to bimodal activity patterns of hawkmoth pollinators

BACKGROUND AND AIMS

The temporal dimensions of floral adaptation to pollinators are not yet well understood, partly because we lack accurate information on the diel rhythms of flower visitation for many pollinators. We investigated whether diel patterns of pollinator visitation to flowers of the African woodland orchid Bonatea polypodantha are synchronized with rhythms of floral anthesis, scent emission and nectar availability.

METHODS

Direct observations and motion-activated cameras were used to identify pollinators of B. polypodantha and to document their activity periods. The timing of pollinaria removal from flowers, emission of scent and availability of nectar was also measured.

RESULTS

We found that B. polypodantha is pollinated exclusively by short-tongued hawkmoths. Pollinaria of the orchid are affixed between the labial palps of the moths and brush over the protruding stigmatic arms. The flowers also receive visits by long-tongued hawkmoths, but these act as nectar thieves. Tracking of pollinaria removal from flowers confirmed that pollination occurs only at night. Camera footage revealed a striking crepuscular pattern of foraging by short-tongued hawkmoths with peaks of activity during the twilight periods at dusk and at dawn. In contrast, long-tongued hawkmoths were found to visit flowers throughout the night. Flowers of B. polypodantha exhibit unimodal peaks of anthesis, scent emission (dominated by nitrogenous aromatics) and nectar availability before or around dusk.

CONCLUSIONS

Flowers of B. polypodantha are pollinated exclusively by short-tongued hawkmoths, which show crepuscular foraging activity at dusk and dawn. Floral phenophases of the orchid are closely synchronized with the peak of pollinator activity at dusk.

Phylogenetic relationships amongst the African genera of subtribe Orchidinae s.l. (Orchidaceae; Orchideae): Implications for subtribal and generic delimitations

Phylogenetic relationships within the Orchideae sensu Pridgeon et al, remain one of the biggest unresolved issues in our understanding of the taxonomy of the orchids. Members of the Orchideae are numerous and widespread in Africa but remain poorly represented in phylogenetic research. In this study we included a broad sampling of African taxa for which we sequenced three plastid (rbcl, matK and trnL + trnL-F) and two nuclear regions (ITS and 18S). We used 368 sequences representing 278 species and 49 genera to infer relationships using the Bayesian Inference and Maximum Likelihood method. Our results show strong support for three clades, two of which almost entirely match the historical circumscription of Orchidinae and Habenariinae, and the third, Bartholininae, sister to the former two, includes the genera Holothrix and Bartholina. Stenoglottis should be assigned to Orchidinae and not to Habenariinae. Several genera such as Habenaria, Cynorkis and Benthamia are shown to be para- or polyphyletic: Bonatea, Centrostigma, Platycoryne and Roeperocharis are all embedded in Habenaria; Physoceras, Arnottia and part of Benthamia are embedded in Cynorkis. We propose a subdivision of Orchideae sensu lato into nine subtribes, but refrain from making generic re-arrangements until more extensive or more in-depth studies have been done.

Hawkmoth pollination of the orchid Habenaria clavata: mechanical wing guides, floral scent and electroantennography

Floral morphology can play a key role in mechanically guiding pollinators towards reproductive structures, particularly when visibility is limited at night, but the functional significance of morphological traits has seldom been considered in this context. Here we describe a remarkably intricate pollination mechanism in the hawkmoth-pollinated African grassland orchid Habenaria clavata, and also document aspects of the reproductive success and chemical ecology of this pollination system. The flowers are pollinated by several short-tongued hawkmoths, particularly Basiothia schenki, which was the most frequent visitor and occurred at all sites. Moths are probably attracted by the strong scent, which was dominated by several oxygenated aromatics that also elicited strong electrophysiological responses from antennae of B. schenki. Apart from the white rostellum lobes and stigma, which serve as a visual guide to the spur entrance, the flower parts are entirely green and indistinguishable from leaves in terms of spectral information. Using motion-activated video cameras we established that the leading edges of the forewings of foraging hawkmoths contact the two upwardly curving petal lobes, and that hawkmoths are then apparently mechanically guided down onto the reproductive structures. Pollinaria are attached in an unusual place – among hairs on the ventral surface of the thorax, between the middle legs – and are brushed over the protruding stigma lobes when the proboscis is fully inserted in the 41-mm-long spur. These results highlight how multiple traits (morphology, spectral reflectance and scent) can act synergistically to ensure transfer of pollen among flowers.

Molecular phylogeny and morphology reveal a new epiphytic species of Habenaria (Orchidaceae; Orchideae; Orchidinae) from Nepal

Habenaria is almost cosmopolitan in distribution having predominantly terrestrial orchids, however; a remarkable epiphytic species with some unique morphological characters was collected from Nepal. We conducted a molecular phylogeny of this unusual Habenaria species using nuclear (ITS) and chloroplast (matK, rbcl) DNA sequence regions to infer its systematic position. Our molecular analyses and morphological treatment recognized this newly collected plant as an undescribed species. This species is described here which is closely related to Habenaria plurifoliata but can be distinguished by having its multiple growing callus-shaped tuber, smaller stature with short stem, longer and wider oblanceolate leaves, peduncle with a foliaceous bract and only one sterile bract, lateral sepals oblong, obtuse, petal apex obtuse, lateral lobes of lip spreading upwards, spur not exceeding the ovary and pedicel.

The genus Bilabrella Lindl. (Orchidaceae, Habenariinae): materials to the taxonomic revision

The aim of the paper is to present materials to the taxonomic revision of the African orchid genus Bilabrella Lindl., based on herbarium materials, specimens conserved in FAA as well as literature. It was compiled using classical taxonomic methods. The research involved determining differences between Bilabrella and other genera of Habenariinae in Africa. Its morphological structure was analysed and key features for the generic taxonomy defined. An infrageneric classification is proposed. A full description of each species and distribution data are provided. The ecological requirements and phenology of all species have been assembled and systematized.

Composição florística e distribuição de Orchidaceae em uma mata ciliar no Rio Grande do Sul

Resumo Matas ciliares são ambientes que apresentam condições favoráveis para o estabelecimento de Orchidaceae, no entanto, diferenças no gradiente altitudinal e alterações na conservação destes ambientes podem influenciar as espécies presentes. Objetivou-se verificar a composição florística e distribuição de Orchidaceae ocorrentes na mata ciliar do Arroio Canhada Funda em Pouso Novo, Rio Grande do Sul. Cinco pontos foram marcados ao longo do arroio em diferentes altitudes para a realização das coletas, as quais foram efetuadas utilizando-se o Método do Caminhamento. Com medidas de dissimilaridade e análise de agrupamento verificou-se a similaridade florística entre os pontos, e a relação entre riqueza e altitude foi analisada por correlação linear de Pearson. Foram inventariadas 36 espécies e 23 gêneros, sendo Gomesa (5), Acianthera (4) e Cyclopogon (4) os mais representativos. A maior diversidade foi observada em altitudes inferiores a 300 m e onde a vegetação estava mais preservada. Acredita-se que a composição e distribuição de Orchidaceae no local foi influenciada principalmente pelo gradiente altitudinal e pelas condições de conservação da mata ciliar.

Phylogenetics of subtribe Orchidinae s.l. (Orchidaceae; Orchidoideae) based on seven markers (plastid matK, psaB, rbcL, trnL-F, trnH-psba, and nuclear nrITS, Xdh): implications for generic delimitation

BACKGROUND

Subtribe Orchidinae (Orchidaceae, Orchidoideae) are a nearly cosmopolitan taxon of terrestrial orchids, comprising about 1800 species in 47 to 60 genera. Although much progress has been made in recent years of phylogenetics of Orchidinae, considerable problems remain to be addressed. Based on molecular phylogenetics, we attempt to illustrate the phylogenetic relationships and discuss generic delimitation within Orchidinae. Seven DNA markers (five plastid and two nuclear), a broad sampling of Orchidinae (400 species in 52 genera) and three methods of phylogenetic analysis (maximum likelihood, maximum parsimony and Bayesian inference) were used.

RESULTS

Orchidinae s.l. are monophyletic. Satyrium is sister to the rest of Orchidinae s.l. Brachycorythis and Schizochilus are successive sister to Asian-European Orchidinae s.s. Sirindhornia and Shizhenia are successive sister to clade formed by Tsaiorchis-Hemipilia-Ponerorchis alliance. Stenoglottis is sister to the Habenaria-Herminium-Peristylus alliance. Habenaria, currently the largest genus in Orchidinae, is polyphyletic and split into two distant clades: one Asian-Australian and the other African-American-Asian. Diplomeris is sister to Herminium s.l. plus Asian-Australian Habenaria.

CONCLUSIONS

We propose to recognize five genera in the Ponerorchis alliance: Hemipilia, Ponerorchis s.l., Sirindhornia, Shizhenia and Tsaiorchis. Splitting Habenaria into two genera based on morphological characters and geographical distribution may be the least disruptive approach, and it is reasonable to keep Satyrium in Orchidinae.

Phylogenetics of tribe Collabieae (Orchidaceae, Epidendroideae) based on four chloroplast genes with morphological appraisal

Collabieae (Orchidaceae) is a long neglected tribe with confusing tribal and generic delimitation and little-understood phylogenetic relationships. Using plastid matK, psaB, rbcL, and trnH-psbA DNA sequences and morphological evidence, the phylogenetic relationships within the tribe Collabieae were assessed as a basis for revising their tribal and generic delimitation. Collabieae (including the previously misplaced mycoheterotrophic Risleya) is supported as monophyletic and nested within a superclade that also includes Epidendreae, Podochileae, Cymbidieae and Vandeae. Risleya is nested in Collabiinae and sister to Chrysoglossum, a relationship which, despite their great vegetative differences, is supported by floral characters. Ania is a distinct genus supported by both morphological and molecular evidence, while redefined Tainia includes Nephelaphyllum and Mischobulbum. Calanthe is paraphyletic and consists four clades; the genera Gastrorchis, Phaius and Cephalantheropsis should be subsumed within Calanthe. Calanthe sect. Ghiesbreghtia is nested within sect. Calanthe, to which the disputed Calanthe delavayi belongs as well. Our results indicate that, in Collabieae, habit evolved from being epiphytic to terrestrial.