New evidence on the origin of mangosteen (Garcinia mangostana L.) based on morphology and ITS sequence

Mangosteen (Garcinia mangostana L.), known as one of the most desirable tropical fruits of Southeast Asia, has been considered as an obligate agamospermous hybrid, thought to have arisen from two wild species, G. celebica L. (syn. G. hombroniana Pierre) and G. malaccensis Hook. f. However, this putative origin was based on a misidentification of G. malaccensis, which was confused for G. penangiana Pierre. Intensive field studies and molecular investigations based on internal transcribed spacer (ITS) sequence data of 22 samples were conducted, which included six samples of true G. malaccensis. Morphological observation shows that mangosteen highly resembles G. malaccensis, particularly in its vegetative and fruit characters, even sharing similar taste of ripe fruits. ITS data revealed that mangosteen shared more than 99 % of its sequence with G. malaccensis with a few accessions identical with wild populations in Peninsular Malaysia. Phylogenetic analysis revealed that clades of mangosteen are paraphyletic per se, but monophyletic if both mangosteen and G. malaccensis are grouped together. This show that mangosteen and G. malaccensis are so closely related that they should be combined together as one species. I propose two theories on the origin of mangosteen, first, that it is a hybrid of different varieties of G. malaccensis, and second, that it may be a product of multiple, superior selections from different populations of female trees of G. malaccensis originating in Peninsular Malaysia

Taxonomic Revision and Molecular Studies of Garcinia Section Garcinia (Guttiferae)

Garcinia section Garcinia is one of 14 sections of the species-rich pantropical genus Garcinia (Guttiferae/Clusiaceae). In its most recent circumscription the section comprised 43 species, mostly of rain forest understorey trees, distributed from eastern India to Fiji, and in Madagascar (Jones, 1980: unpublished Phd. Thesis, University of Leicester). Its most famous member is the fruit tree, mangosteen (G. mangostana). Taxonomic revision of section Garcinia reduces the number of species from 43 to 16 with five varieties, with distribution from eastern India to Malesia. A total of nine species are excluded, 19 species are reduced to synonyms and five species are insufficiently known to be classified. Within sect. Garcinia, G. acuticosta, G. discoidea, G. exiguous, G. ochraceus and G. sangudsangud are newly described, G. diospyrifolia var. arborea, G. diospyrifolia var. minor and G. malaccensis var. pseudomangostana are new varieties, and G. cataractalis, previously unassigned to any section by Jones (1980) is newly included. Species limits are defined on the basis of combinations of characters such as shape of stamens and presence of pistillode, fruit type, and leaf characters such as shape, size, venation pattern and type of glandular lines. A total of 83 accessions representing 42 Garcinia species were sequenced for the nuclear ribosomal internal transcribed spacer (ITS) region, while 50 accessions (30 spp.) and 24 accessions (16 spp.) were sequenced for the chloroplast non-coding regions trnS-G and trnD-T respectively. Of these, 30 accessions or ten spp. (ITS), 23 accessions or nine spp. (trnS-G) and 17 accessions or nine spp. (trnD-T) belong to sect. Garcinia. Parsimony and Bayesian analyses show that the ITS data are more phylogenetically informative and provide better resolution for sectional and species relationships compared to trnS-G and trnD-T. Most of the sections delimited by Jones (1980) proved to be monophyletic but sect. Garcinia is not. Garcinia maingayi, G. trianii and G. costata, assigned to sect. Garcinia by Jones, are in a separate clade that is strongly supported as sister to sect. Brindonia. These species have significantly different morphological characters from sect. Garcinia, and should be excluded from it. Characters that are important for sectional delimitation are inflorescences that are simple cymes, stamen bundles that are 4-angled or 4-lobed, and fruits with a smooth surface. Four major clades in sect. Garcinia are supported by the shape of the stamen bundles, the shape of the fruit and the stigma, and fruit wall characters. ITS trees are significantly incongruent with plastid trees because of the placement of G. rigida, which could reflect a hybrid origin. Another hybrid species, the cultivated mangosteen, could be the product of hybridisation events between varieties of G. malaccensis if mangosteen is proven to be an obligate agamosperm. However, if mangosteen is a facultative agamosperm, G. malaccensis is likely to be the female parent, but any other Garcinia species could be the putative paternal species. Phylogenetic trees of ITS show that most Garcinia species from east of Wallace’s Line are nested within species from the west. This might reflect dispersal of species across this biogeographic division from west to east when the Sahul and Sunda shelves converged (c. 20 MY).This hypothesis is supported by the estimated divergence of accessions of G. rigida from the east of Wallace’s Line, from their most recent common ancestor to the west of the line, not later than 21.58+/-2.90 MY

An annotated checklist of higher plants in Ayer Hitam Forest Reserve, Puchong, Selangor

Ayer Hitam Forest Reserve is a Kelat-Kedondong subtype of the lowland dipterocarp forest situated in the Klang Valley which is currently undergoing a tremendous pace of socio-economic and physical development. The forest had been logged many times in the last 60 years or so and most vegetation niches are beginning to recover to their climax again. Our expedition, from 2-5 May 2000 involved a few botanists who observed and collected specimens of higher plants. The enumeration provided here is based only on the specimens collected during the expedition, includes 262 species of vascular plants belonging to 142 genera and 56 families: The Myrtaceae, with 22 species is the largest family in the checklist, followed by Euphorbiaceae, Dipterocarpaceae and Annonaceae with 21, 17 and 14 species, respectively. Species-wise the genus Knema, is the largest with 13 species, followed by Memecylon, Syzygium and Diospyros with 9, 7, and 7 species, respectively

Tree taxa inventory at Ayer Hitam Forest base-camp

An inventory at the base camp along 6 new trails recorded a total of 86 species of seed plant taxa in 68 genera and 32 families. Of this number 22 timber species, 9 fruit tree species, 3 species with medicinal values and 8 species producing dye and tannins were identified. 6 Peninsular Malaysian endemics are also found here, two being new records for Selangor. This area is useful for teaching and practical training for forestry related and environmental courses

Anthropological interference on the vegetation of Wassaniya Forest Reserve of Sokoto State Nigeria

A participatory rural appraisal study was conducted using inclusion and exclusion criteria within twelve communities residing around Wassaniya Forest Reserve in Sokoto State Northern Nigeria, in order to ascertain the anthropological interference on the forest reserve. A multistage random sampling technique was adopted for selecting 120 respondents, from 3 villages out of 2 district each in two local government areas of Sokoto State. The results reveals different means of forest exploitation that were largely due to anthropological (human) interference. These includes collection of fuel wood, illegal hunting, sales of Non-timber forest products, over-grazing, uncontrolled bushburning, carving of local farm implements, thatching and collection of charcoal for black smith. Other means of forest exploitation found includes but not limited to collection of fruits and food from the forest, collection of herbs for medicinal purposes, Tannings, Gums and resins. The overall dependency of all the communities on forest for their daily needs shows that there is urgent needs for actions to be taken so as to diversify their income, increase their awareness on the sustainable forest management in order to reduce the risk of deforestation and desertification and the adverse effects of global warming within the area

Impacts of Recreation Activities on Growth and Physiological Characteristics of Upper Mountain Vegetation

This study examines the impacts of recreation activities on Mount Tahan (2187 m a.s.l); the highest mountain in Peninsular Malaysia by assessing tree diameter, height, leaf area, sapwood area, and chlorophyll fluorescence (CF) of selected species. Vegetation cover was also determined by counting the number of species. Two most dominant tree species in the study plots, i.e., Tristaniopsis fruticosa and Baeckea frutescens were selected as representative to assess the impacts on the vegetation growth. Both tree species dominated over 50% of total vegetation in both areas. Meanwhile, CF was determined on T. fruticosa since this species was the only broadleaf species found in both areas. Four plots sized 20 m X 20 m representing each disturbed and undisturbed were established in camping and trampling areas. The total number of plant species recorded was 29 in both camping and trampling areas but was found less in disturbed plots. Impacts of trampling and camping on all the parameters at higher altitude in disturbed plots were significantly different from those in the undisturbed plots. For trampling, all growth parameters taken in disturbed plots were found lower than in undisturbed plots. For camping, however, the mean values of vegetation cover were found lower in disturbed plots compared to undisturbed plots but the mean values of tree diameter, height, leaf area and sapwood area were found greater in disturbed than in undisturbed plots. In contrast, all CF parameters were found higher in disturbed plots for both trampling and camping areas

Genetic structures across a biogeographical barrier reflect dispersal potential of four Southeast Asian mangrove plant species

Aim: Biogeographical barriers restrict the movement of individuals, resulting in population divergence, genetic differentiation, endemism and speciation. Yet, some barriers demonstrate unequal effect across species depending on species dispersal, which manifests in varying genetic structure. We test the hypotheses that the genetic structure of four coastal mangrove species would reflect differences in dispersal potential across the Malay Peninsula, a major biogeographical barrier in the Indo-West Pacific region. Location: East and west coasts of the Malay Peninsula. Taxon Mangrove trees Avicennia alba, Sonneratia alba, Bruguiera gymnorhiza and Rhizophora mucronata. Methods: For each species, we characterized genetic structure and gene flow using 7–12 species-specific nuclear microsatellite markers. We tested for east–west genetic differentiation across the peninsula, a stepping-stone migration pattern, and assessed the proportion of recent dispersal and direction of historical migration along the Malacca Strait. Results: Significant east–west genetic differentiation across the peninsula was observed in A. alba, S. alba and B. gymnorhiza, and the effect was most pronounced for the two species with lower dispersal potential (A. alba, S. alba). In contrast, the two species with higher dispersal potential (B. gymnorhiza and R. mucronata) exhibited much higher proportion of recent inter-population migration along the Malacca Strait. The signature of historical colonization from refugia in the Andaman Sea (north-to-south migration along the Malacca Strait) predominated for A. alba and S. alba. Historical south–north migration predominated for R. mucronata and B. gymnorhiza. Main conclusions: This study implicated dispersal potential as a cause of varying mangrove species genetic structure across a biogeographical barrier. The Malay Peninsula functions as a filter to gene flow rather than a barrier. The genetic structure in mangrove species with a higher dispersal potential is more congruent with contemporary gene flow while that of species with a lower dispersal potential reflects historical processes. Our findings hint at the role of dispersal potential as a predictor of gene flow in mangroves

Genetic Structure and Population Demographic History of a Widespread Mangrove Plant Xylocarpus granatum J. Koenig across the Indo-West Pacific Region

Xylocarpus granatum J. Koenig is one of the most widespread core component species of mangrove forests in the Indo-West Pacific (IWP) region, and as such is suitable for examining how genetic structure is generated across spatiotemporal scales. We evaluated the genetic structure of this species using maternally inherited chloroplast (cp) and bi-parentally inherited nuclear DNA markers, with samples collected across the species range. Both cp and nuclear DNA showed generally similar patterns, revealing three genetic groups in the Indian Ocean, South China Sea (with Palau), and Oceania, respectively. The genetic diversity of the Oceania group was significantly lower, and the level of population differentiation within the Oceania group was significantly higher, than in the South China Sea group. These results revealed that in addition to the Malay Peninsula—a common land barrier for mangroves—there is a genetic barrier in an oceanic region of the West Pacific that prevents gene flow among populations. Moreover, demographic inference suggested that these patterns were generated in relation to sea level changes during the last glacial period and the emergence of Sahul Shelf which lied northwest of Australia. We propose that the three genetic groups should be considered independent conservation units, and that the Oceania group has a higher conservation priority

Development of 11 polymorphic microsatellite markers for Xylocarpus granatum (Meliaceae) using next-generation sequencing technology

Human impacts have seriously damaged mangroves, and conservation of mangroves will require information on local and regional population genetic structures. Here, we report the development and polymorphism of eleven novel microsatellite markers, developed using next- generation sequencing on 56 samples of widespread man- grove species Xylocarpus granatum (Meliaceae) from nine populations across the Indo-West Pacific region. All loci were found to be polymorphic, with the number of alleles per locus ranging from four to 19. In a population from Sabah (Malaysia), the mean observed and expected heterozygosity per locus was 0.59 and 0.58, respectively. No null allele, significant linkage disequilibrium or deviation from Hardy–Weinberg equilibrium was detected among all loci. The eleven markers developed can be valuable tools to conservation genetics of this species across its distributional range

Bruguiera hainesii, a critically endangered mangrove species, is a hybrid between B. Cylindrica and B. Gymnorhiza (Rhizophoraceae)

Bruguiera hainesii (Rhizophoraceae) is one of the two Critically Endangered mangrove species listed in the IUCN Red List of Threatened Species. Although the species is vulnerable to extinction, its genetic diversity and the evolutionary relationships with other Bruguiera species are not well understood. Also, intermediate morphological characters imply that the species might be of hybrid origin. To clarify the genetic relationship between B. hainesii and other Bruguiera species, we conducted molecular analyses including all six Bruguiera species using DNA sequences of two nuclear genes (CesA and UNK) and three chloroplast regions (intergenic spacer regions of trnL-trnF, trnS-trnG and atpB-rbcL). For nuclear DNA markers, all nine B. hainesii samples from five populations were heterozygous at both loci, with one allele was shared with B. cylindrica, and the other with B. gymnorhiza. For chloroplast DNA markers, the two haplotypes found in B. hainesii were shared only by B. cylindrica. These results suggested that B. hainesii is a hybrid between B. cylindrica as the maternal parent and B. gymnorhiza as the paternal one. Furthermore, chloroplast DNA haplotypes found in B. hainesii suggest that hybridization has occurred independently in regions where the distribution ranges of the parental species meet. As the IUCN Red List of Threatened Species currently excludes hybrids (except for apomictic plant hybrids), the conservation status of B. hainesii should be reconsidered