Conservation of Madagascar’s granite outcrop orchids: the influence of fire and moisture

Whitman, Melissa; Medler, Michael J.; Randriamanindry, Jean Jacques; Rabakonandrianina, Elisabeth

doi:10.15517/lank.v11i1.18315

Cited by 15 publications

(12 citation statements)

References 20 publications

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“…One of the principal threats in the CHM habitats is fire (Hermans et al 2007 ; Whitman et al 2011 ) and a number of lithophytic orchids may be more prone to threats of extinction from the studied habitats than terrestrial orchids. This group of vulnerable taxa from the CHM should be prioritised and targeted for ex situ collections with IVC as a potential tool to complement conventional seed collecting.…”

Section: Discussionmentioning

confidence: 99%

Collecting near mature and immature orchid seeds for ex situ conservation: ‘in vitro collecting’ as a case study

et al. 2017

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BackgroundLack of phenological information and efficient collecting methods are considered impediments for orchid seed collecting. This leads to opportunistic collecting as part of general seed collecting schedules that may last few weeks especially in remote areas. The study explored the feasibility of collecting near mature and immature seeds to support conservation action plans. Mature, near mature and immature seeds of orchids were collected from the wild in the Central Highlands of Madagascar (CHM). Seed capsules were collected in sterile culture medium in the wild, to prevent deterioration of seeds inside the capsule after collecting, later to be cultured under laboratory conditions.ResultsSeed capsules collected by the in vitro collecting (IVC) method were kept in very good condition for up to 4 weeks before germination under in vitro conditions. Significantly faster and higher germination rate (p < 0.001) than mature seeds was observed in a number of taxa collected during a 3 year-long study. In some taxa even immature seeds, with no apparent sign of testa covering the embryo, germinated following IVC where mature seeds failed to germinate.ConclusionsWe propose that IVC method has potential to complement conventional seed collecting by increasing the germplasm that can be used in integrated conservation action plans. Improvements can be made in developing collections for taxa from biodiversity hotspots and remote areas where collecting requires considerable resources. This method can further be used on a wider selection of plants from different geographic areas and on embryo rescue programmes for economically important plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-017-0187-5) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Collecting near mature and immature orchid seeds for ex situ conservation: ‘in vitro collecting’ as a case study

et al. 2017

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“…Whitman et al . [ 98 ] reported that lithophytic Angraecinae are tolerant to limited moisture availability, and chronic bushfire did not kill the population of Angraecum sororium and Jumellea rigida but only reduced their expansion. But diversification slowdown could be also the result of ecological limitation, competition, access to pollinators, species carrying capacity [ 99 , 100 ], or maintenance of niche similarity [ 101 ].…”

Section: Discussionmentioning

confidence: 99%

Diversification of Angraecum (Orchidaceae, Vandeae) in Madagascar: Revised Phylogeny Reveals Species Accumulation through Time Rather than Rapid Radiation

Andriananjamanantsoa

Engberg²,

Louis³

et al. 2016

PLoS ONE

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Angraecum is the largest genus of subtribe Angraecinae (Orchidaceae) with about 221 species. Madagascar is the center of the diversity for the genus with ca. 142 species, of which 90% are endemic. The great morphological diversity associated with species diversification in the genus on the island of Madagascar offers valuable insights for macroevolutionary studies. Phylogenies of the Angraecinae have been published but a lack of taxon and character sampling and their limited taxonomic resolution limit their uses for macroevolutionary studies. We present a new phylogeny of Angraecum based on chloroplast sequence data (matk, rps16, trnL), nuclear ribosomal (ITS2) and 39 morphological characters from 194 Angraecinae species of which 69 were newly sampled. Using this phylogeny, we evaluated the monophyly of the sections of Angraecum as defined by Garay and investigated the patterns of species diversification within the genus. We used maximum parsimony and bayesian analyses to generate phylogenetic trees and dated divergence times of the phylogeny. We analyzed diversification patterns within Angraecinae and Angraecum with an emphasis on four floral characters (flower color, flower size, labellum position, spur length) using macroevolutionary models to evaluate which characters or character states are associated with speciation rates, and inferred ancestral states of these characters. The phylogenetic analysis showed the polyphyly of Angraecum sensu lato and of all Angraecum sections except sect. Hadrangis, and that morphology can be consistent with the phylogeny. It appeared that the characters (flower color, flower size, spur length) formerly used by many authors to delineate Angraecum groups were insufficient to do so. However, the newly described character, position of the labellum (uppermost and lowermost), was the main character delimiting clades within a monophyletic Angraecum sensu stricto. This character also appeared to be associated with speciation rates in Angraecum. The macroevolutionary model-based phylogeny failed to detect shifts in diversification that could be associated directly with morphological diversification. Diversification in Angraecum resulted from gradual species accumulation through time rather than from rapid radiation, a diversification pattern often encountered in tropical rain forests.

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“…The spatial distribution patterns of P. stachyodes (clustered occurrence at short spatial scales shifting to random occurrence with distance, combined with clumped abundance) are not surprising, given models of orchid seed dispersal patterns (Kindlmann et al 2014), and field observations reported in both temperate and tropical habitats (e.g., Jacquemyn et al 2007, Whitman et al 2011. These spatial patterns are also common with tropical tree species (Condit et al 2000) and may reflect either dispersal limitation or highly specific niche requirements (Brown et al 1995).…”

Section: Discussionmentioning

confidence: 84%

“…Habitat characteristics that promote larger sized P. stachyodes, and thus greater reproductive effort and eventual seed output, are not necessarily the same conditions needed for seedling establishment or the maintenance of subpopulations. Disjunction between habitat needs at different life stages is feasible, given the overall ecological complexity attributed to this taxonomic group (Givnish 1982, Jacquemyn et al 2007, Whitman et al 2011, Bunch et al 2013. For instance, specificity of tree host substrate was not linked to adult orchid fitness or probability of flowering, but may be attributed to conditions necessary for early life stages (Gowland et al 2011).…”

Section: Linking Habitat Characteristics With Possible Life History Smentioning

confidence: 99%

Terrestrial orchids in a tropical forest: best sites for abundance differ from those for reproduction

Whitman

Ackerman

2015

Ecology

Self Cite

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Abstract. Suitable habitat for a species is often modeled by linking its distribution patterns with landscape characteristics. However, modeling the relationship between fitness and landscape characteristics is less common. In this study we take a novel approach towards species distribution modeling (SDM) by investigating factors important not only for species occurrence, but also abundance and physical size, as well as fitness measures. We used the Neotropical terrestrial orchid Prescottia stachyodes as our focal species, and compiled geospatial information on habitat and neighboring plants for use in a two-part conditional SDM that accounted for zero inflation and reduced spatial autocorrelation bias. First, we modeled orchid occurrence, and then within suitable sites we contrasted habitat characteristics important for orchid abundance as compared to plant size. We then tested possible fitness implications, informed by analyses of allometric scaling of reproductive effort and lamina area, as well as size-density relationships in areas of P. stachyodes co-occurrence. We determined that orchid presence was based on a combination of biotic and abiotic factors (indicator species, diffuse solar radiation). Within these sites, P. stachyodes abundance was higher on flat terrain, with fine, moderately well-drained soil, and areas without other native orchids, whereas plant size was greater in less rocky areas. In turn, plant size determined reproductive effort, with floral display height proportionate to lamina area (more photosynthates); however, allometric scaling of flower quantity suggests a higher energy cost for production, or maintenance, of flowers. Overall, habitat factors most important for abundance differed from those for size (and thus reproductive effort), suggesting that sites optimal for either recruitment or survival may not be the primary source of seeds. For plots with multiple P. stachyodes plants, size-density relationships differed depending on the size class examined, which may reflect context-dependent population dynamics. Thus, ecological resolution provided by SDM can be enhanced by incorporating abundance and fitness measures.

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Conservation of Madagascar’s granite outcrop orchids: the influence of fire and moisture

Cited by 15 publications

References 20 publications

Collecting near mature and immature orchid seeds for ex situ conservation: ‘in vitro collecting’ as a case study

Collecting near mature and immature orchid seeds for ex situ conservation: ‘in vitro collecting’ as a case study

Diversification of Angraecum (Orchidaceae, Vandeae) in Madagascar: Revised Phylogeny Reveals Species Accumulation through Time Rather than Rapid Radiation

Terrestrial orchids in a tropical forest: best sites for abundance differ from those for reproduction

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