Displaying publications 121 - 137 of 137 in total

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  1. Ab Wahab SZ, Nik Hussain NH, Zakaria R, Abdul Kadir A, Mohamed N, Tohit NM, et al.
    Complement Ther Med, 2018 Dec;41:154-160.
    PMID: 30477832 DOI: 10.1016/j.ctim.2018.08.015
    OBJECTIVE: To investigate the long-term effects of Tualang Honey versus Honey Cocktail (mixture of honey, bee bread, and royal jelly) on cardiovascular markers and anthropometric measurements of postmenopausal women.

    METHODS: We conducted a randomised, double blinded, two-armed parallel study comparing 20 g/day of Tualang Honey versus 20 g/day Honey Cocktail among postmenopausal women aged 45-65 years. The cardiovascular parameters and anthropometrics measurements were assessed at baseline, 6 months, and 12 months of the intervention.

    RESULTS: 100 subjects were successfully randomised into the groups. There was a significant decrease in the diastolic blood pressure from 77.92 mmHg at baseline to 73.45 mmHg at 12 months (F-statistic = 2.55, p-value = 0.047) in the Tualang Honey group compared to Honey Cocktail. There was also a significant decrease in the fasting blood sugar from 6.11 mmol/L at baseline to 5.71 mmol/L at 12 months (F-statistic = 4.03, p-value = 0.021) in the Tualang Honey group compared to the Honey Cocktail group. The body mass index remained unchanged at 27 kg/m2 (F-statistic = 1.60, p-value = 0.010) throughout 12 months of the intervention in the Honey Cocktail group.

    CONCLUSION: Subjects who received Honey Cocktail showed remarkable effects on body mass index. However, Tualang Honey supplementation showed superior effect in lowering diastolic blood pressure and fasting blood sugar compared to Honey Cocktail. Further studies are required to ascertain the underlying mechanism(s) of Tualang Honey and Honey Cocktail on each observed parameter.

  2. Che Ya SN, Muhamad R, Zakaria R, Mohd Zain N, Ishak A, Hassan II, et al.
    Arch Sex Behav, 2021 Nov 08.
    PMID: 34750771 DOI: 10.1007/s10508-021-02051-3
    Sexuality is currently neglected in the medical care of cancer patients although female sexual dysfunction (FSD) and sexual problems are highly prevalent among breast cancer patients in Malaysia. This paper explores the consequences of breast cancer and its treatment on the sexuality and sexual health of women with breast cancer using a qualitative design and a phenomenological methodology. Fourteen married women with breast cancer who fulfill the criteria for FSD from Kelantan, Malaysia participated in two interviews: in-depth interview and followed by photo-elicitation interview after two weeks duration. The interviews were audio-recorded, transcribed verbatim, and analyzed using thematic analysis. We identified overlapping themes that can be explained by sexual script theory. Breast cancer treatments disturb the sex response cycle, leading to changes in sexuality, from intimacy in marriage to women preferring physical affection to intercourse. The women struggled with a perceived imperfection about symbol of femininity after noticing changes in their husbands' sexual performance and after experiencing their own sentiments of inadequacy as a wife. Fear and guilt surfaced as part of the journey, accompanied by frustration on the part of the spouse, or him becoming more attentive. This study highlights the problem of breast cancer and its treatment as regards the sexual well-being of patients and their spouses. Hence, recognizing and addressing sexual health will improve the overall experience for survivors.
  3. Zakaria WNA, Sasongko TH, Al-Rahbi B, Al-Sowayan N, Ahmad AH, Zakaria R, et al.
    Psychiatr Genet, 2023 Apr 01;33(2):37-49.
    PMID: 36825838 DOI: 10.1097/YPG.0000000000000336
    This study aimed to perform a bibliometric analysis on genetic studies in schizophrenia in the pregenome-wide association studies (GWAS) and post-GWAS era. We searched the literature on genes and schizophrenia using the Scopus database. The documents increased with time, especially after the human genome project and International HapMap Project, with the highest citation in 2008. The top occurrence author keywords were discovered to be different in the pre-GWAS and post-GWAS eras, reflecting the progress of genetic studies connected to schizophrenia. Emerging keywords highlighted a trend towards an application of precision medicine, showing an interplay of environmental exposures as well as genetic factors in schizophrenia pathogenesis, progression, and response to therapy. In conclusion, the gene and schizophrenia literature has grown rapidly after the human genome project, and the temporal variation in the author keywords pattern reflects the trend of genetic studies related to schizophrenia in the pre-GWAS and post-GWAS era.
  4. Othman Z, Abdul Halim AS, Azman KF, Ahmad AH, Zakaria R, Sirajudeen KNS, et al.
    Front Aging Neurosci, 2022;14:876159.
    PMID: 35572132 DOI: 10.3389/fnagi.2022.876159
    OBJECTIVES: This study aimed to profile the cognitive aging research landscape from 1956 to 2021.

    METHODS: A total of 3,779 documents were retrieved from the Scopus database for the bibliometric analysis and network visualization. By comparing each keyword's overall connection strength (centrality), frequency (density), and average year of publication (novelty) to the calculated median values acquired from the overlay view of the VOSviewer map, the enhanced strategic diagrams (ESDs) were constructed.

    RESULTS: The findings showed an increasing trend in the number of publications. The United States leads the contributing countries in cognitive aging research. The scientific productivity pattern obeyed Lotka's law. The most productive researcher was Deary, I. J., with the highest number of publications. The collaborative index showed an increasing trend from 1980 onwards. Frontiers in Aging Neuroscience is the most prestigious journal in the field of cognitive aging research. In Bradford core journals zone 1, the top 10 core journals of cognitive aging research provided more than half of the total articles (697, or 55.36 percent).

    CONCLUSIONS: For the next decades, the trending topics in cognitive aging research include neuropsychological assessment, functional connectivity, human immunodeficiency virus (HIV), decision-making, gender, compensation, default mode network, learning and memory, brain-derived neurotrophic factor (BDNF), obesity, D-galactose, epigenetics, frailty, mortality, mini-mental state examination (MMSE), anxiety, and gait speed.

  5. Vit P, van der Meulen J, Diaz M, Pedro SRM, Esperança I, Zakaria R, et al.
    Curr Res Food Sci, 2023;6:100386.
    PMID: 36846470 DOI: 10.1016/j.crfs.2022.11.005
    The biodiversity of Ecuadorian stingless bees is almost 200 species. Traditional pot-honey harvest in Ecuador is mostly done from nests of the three genera selected here Geotrigona Moure, 1943, Melipona Illiger, 1806, and Scaptotrigona Moure, 1942. The 20 pot-honey samples collected from cerumen pots and three ethnic honeys "abeja de tierra", "bermejo", and "cushillomishki" were analyzed for qualitative and quantitative targeted 1H-NMR honey profiling, and for the Honey Authenticity Test by Interphase Emulsion (HATIE). Extensive data of targeted organic compounds (41 parameters) were identified, quantified, and described. The three honey types were compared by ANOVA. Amino acids, ethanol, hydroxymethylfurfural, aliphatic organic acids, sugars, and markers of botanical origin. The number of phases observed with the HATIE were one in Scaptotrigona and three in Geotrigona and Melipona honeys. Acetic acid (19.60 ± 1.45 g/kg) and lactic acid (24.30 ± 1.65 g/kg) were particularly high in Geotrigona honey (in contrast to 1.3 g/kg acetic acid and 1.6 g/kg lactic acid in Melipona and Scaptotrigona), and with the lowest fructose + glucose (18.39 ± 1.68) g/100g honey compared to Melipona (52.87 ± 1.75) and Scaptotrigona (52.17 ± 0.60). Three local honeys were tested using PCA (Principal Component Analysis), two were assigned with a correct declared bee origin, but "bermejo" was not a Melipona and grouped with the Scaptotrigona cluster. However after HCA (Hierarchical Cluster Analysis) the three honeys were positioned in the Melipona-Scaptotrigona cluster. This research supports targeted 1H-NMR-based profiling of pot-honey metabolomics approach for multi-parameter visualization of organic compounds, as well as descriptive and pertained multivariate statistics (HCA and PCA) to discriminate the stingless bee genus in a set of Geotrigona, Melipona and Scaptotrigona honey types. The NMR characterization of Ecuadorian honey produced by stingless bees emphasizes the need for regulatory norms. A final note on stingless bee markers in pot-honey metabolites which should be screened for those that may extract phylogenetic signals from nutritional traits of honey. Scaptotrigona vitorum honey revealed biosurfactant activity in the HATIE, originating a fingerprint Honey Biosurfactant Test (HBT) for the genus in this set of pot-honeys.
  6. Ab Aziz S, Mohd Nasir MH, Jusoh AR, Azman KF, Ismail CAN, Ahmad AH, et al.
    Heliyon, 2024 Feb 29;10(4):e26106.
    PMID: 38390049 DOI: 10.1016/j.heliyon.2024.e26106
    Olfactory marker protein (OMP) is extensively studied in mature olfactory receptor neurons (ORNs) for understanding olfaction physiology. However, no bibliometric analysis on this topic exists. We conducted a bibliometric analysis of OMP research articles, wherein the publication count was assessed by year, country, journal, and author, collaboration by country, and productivity of the authors. Additionally, key terms and research themes were identified. Using the search phrase "olfactory marker protein" in Scopus, we retrieved 691 original research articles by 2487 authors since 1974. Publications showed an increasing trend, with the United States leading in quantity and collaboration. Our thematic map highlights "Olfactory bulb, regeneration, olfactory" as the primary research domain, while "olfaction, olfactory sensory neuron, glomerulus" and "olfactory receptor neurons, apoptosis, olfactory dysfunction" emerge as essential future research topics. These bibliometric findings offer insights into the global OMP research landscape, guiding researchers in potential collaborations and intriguing future research fields.
  7. Samsir S, Zakaria R, Razak SA, Ismail MS, Rahim MZA, Lin CS, et al.
    Malays J Med Sci, 2018 Sep;25(5):68-78.
    PMID: 30914864 MyJurnal DOI: 10.21315/mjms2018.25.5.7
    Background: Neuroimaging is increasingly used to locate the lesion that causes cerebral palsy (CP) and its extent in the brains of CP patients. Conventional structural magnetic resonance imaging (MRI) does not indicate the connectional pattern of white matter; however, with the help of diffusion MRI, fibre tracking of white matter can be done.

    Methods: We used diffusion MRI and probabilistic tractography to identify the putative white matter connectivity in the brains of 10 CP patients. We tracked the corticospinal tract (CST) of the patients' upper and lower limbs and calculated the white matter connectivity, as indexed by streamlines representing the probability of connection of the CST.

    Results: Our results show that diffusion MRI with probabilistic tractography, while having some relation with the clinical diagnosis of CP, reveals a high degree of individual variation in the streamlines representing the CST for upper and lower limbs.

    Conclusion: Diffusion MRI with probabilistic tractography provides the state of connectivity from lesioned areas to other parts of the brain and is potentially beneficial to be used as an adjunct to the clinical management of CP, providing a means to monitor intervention outcomes.

  8. Teridi MA, Sookhakian M, Basirun WJ, Zakaria R, Schneider FK, da Silva WJ, et al.
    Nanoscale, 2015 Apr 28;7(16):7091-100.
    PMID: 25640454 DOI: 10.1039/c4nr05874g
    High performance organic devices including polymer solar cells (PSCs) and light emitting diodes (PLEDs) were successfully demonstrated with the presence of highly ordered nanoimprinted Au nanodisks (Au NDs) in their solution-processed active/emissive layers, respectively. PSCs and PLEDs were fabricated using a low bandgap polymer and acceptor, nitrogen doped multiwalled carbon nanotubes poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]-thiophenediyl] (n-MWCNTs:PTB7), and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) and (4,4-N,N-dicarbazole) biphenyl (CBP) doped with tris(2-phenylpyridine) iridium(iii) (Ir(ppy)3) as active/emissive layers, respectively. We synthesized nitrogen doped graphene and used it as anodic buffer layer in both devices. The localized surface plasmon resonance (LSPR) effect from Au NDs clearly contributed to the increase in light absorption/emission in the active layers from electromagnetic field enhancement, which originated from the excited LSPR in PSCs and PLEDs. In addition to the high density of LSPR and strong exciton-SP coupling, the electroluminescent (EL) enhancement is ascribed to enhanced spontaneous emission rates. This is due to the plasmonic near-field effect induced by Au NDs. The PSCs and PLEDs exhibited 14.98% (8.08% to 9.29%) under one sun of simulated air mass 1.5 global (AM1.5G) illumination (100 mW cm(-2)) and 19.18% (8.24 to 9.82 lm W(-1)) enhancement in the power conversion efficiencies (PCEs) compared to the control devices without Au NDs.
  9. Teik CK, Basri NI, Abdul Karim AK, Azrai Abu M, Ahmad MF, Abdul Ghani NA, et al.
    Arch Iran Med, 2019 06 01;22(6):340-343.
    PMID: 31356101
    Cerebral arteriovenous malformation (AVM) is a rare entity with an estimated prevalence of 0.01-0.05% in the general population. We reviewed hospital obstetric records during 2010-2017 and reported a case series of six patients with cerebral AVM in pregnancy, of which five patients had successful pregnancy, and one maternal mortality.
  10. Che Ya SN, Muhamad R, Mohd Zain N, Zakaria R, Ishak A, Hassan II, et al.
    Sex Med, 2021 Jun;9(3):100336.
    PMID: 33794448 DOI: 10.1016/j.esxm.2021.100336
    INTRODUCTION: Women' sexuality becomes complex after breast cancer diagnosis and sexual health is highly neglected in the management of the illness.

    AIMS: To explore the coping and strategies to overcome sexuality problems and sexual dysfunction among women with breast cancer.

    MATERIAL AND METHODS: Using the in-depth and photo-elicitation interview methods, this qualitative study following phenomenological analysis was conducted on fourteen married female respondents with breast cancer and had the positive result for female sexual dysfunction (FSD) screened by Female Sexual Function Index (FSFI-6 items) from Kelantan, Malaysia. The interviews data were audio-recorded, transcribed verbatim and managed in analytic computer software NVivo11 Pro. The transcriptions were analyzed using thematic analysis by referring to the meaning-making theory.

    MAIN OUTCOME MEASURES: We identified overlapping themes of coping and strategies among women with breast cancer to overcome sexual problems and sexual dysfunction which correspond with meaning-making theory.

    RESULTS: Three themes have emerged. Women with breast cancer that developed sexuality problem and sexual dysfunction strived to accept the illness using religious belief and conform by altering sexual practices. These individuals positively look for a solution by seeking formal healthcare advice, modify their physical appearance, active discussion with the husband and support from other survivors. A few of them passively struggle with the subject by averting the intimacy and receptive toward polygamy.

    CONCLUSION: This study highlighted the various mechanisms that emphasized the pivotal role of religious belief and relationship context as key factors in the coping strategies among women with breast cancer in Malaysia. The finding may not be generalized to other countries. Che Ya SN, Muhamad R, Zain NM, et al. Coping Strategies for Sexual Problems and Sexual Dysfunction Amongst Malay Women With Breast Cancer. A Qualitative Study. Sex Med 2021;9:100336.

  11. Abg Abd Wahab DY, Gau CH, Zakaria R, Muthu Karuppan MK, A-Rahbi BS, Abdullah Z, et al.
    Biomed Res Int, 2019;2019:1767203.
    PMID: 31815123 DOI: 10.1155/2019/1767203
    Neurological diseases particularly Alzheimer's disease (AD), Parkinson's disease (PD), stroke, and epilepsy are on the rise all around the world causing morbidity and mortality globally with a common symptom of gradual loss or impairment of motor behaviour. Striatum, which is a component of the basal ganglia, is involved in facilitating voluntary movement while the cerebellum is involved in the maintenance of balance and coordination of voluntary movements. Dopamine, serotonin, gamma-aminobutyric acid (GABA), and glutamate, to name a few, interact in regulating the excitation and inhibition of motor neurons. In another hand, interestingly, the motor loss associated with neurological diseases is possibly resulted from neuroinflammation induced by the neuroimmune system. Toll-like receptors (TLRs) are present in the central nervous system (CNS), specifically and primarily expressed in microglia and are also found on neurons and astrocytes, functioning mainly in the regulation of proinflammatory cytokine production. TLRs are always found to be associated or involved in the induction of neuroinflammation in neurodegenerative diseases. Activation of toll-like receptor 4 (TLR4) through TLR4 agonist, lipopolysaccharide (LPS), stimulation initiate a signaling cascade whereby the TLR4-LPS interaction has been found to result in physiological and behavioural changes including retardation of motor activity in the mouse model. TLR4 inhibitor TAK-242 was reflected in the reduction of the spinal cord pathology along with the motor improvement in ALS mouse. There is cross talk with neuroinflammation and neurochemicals. For example, TLR4 activation by LPS is noted to release proinflammatory cytokines, IL-1β, from microglia that subsequently suppresses GABA receptor activities at the postsynaptic site and reduces GABA synthesis at the presynaptic site. Glial glutamate transporter activities are also found to be suppressed, showing the association between TLR4 activation and the related neurotransmitters and corresponding receptors and transporters in the event of neuroinflammation. This review is helpful to understand the connection between neurotransmitter and neuroinflammation in striatum- and cerebellum-mediated motor behaviour.
  12. Ahmad AH, Zabri SH, Roslan SM, Ayob NA, Abd Hamid AI, Mohd Taib NH, et al.
    Malays J Med Sci, 2024 Aug;31(4):111-125.
    PMID: 39247106 DOI: 10.21315/mjms2024.31.4.9
    BACKGROUND: The human reward system has been extensively studied using neuroimaging. This bibliometric analysis aimed to determine the global trend in diffusion magnetic resonance imaging (dMRI) and human reward research in terms of the number of documents, the most active countries and their collaborating countries, the top journals and institutions, the most prominent authors and most cited articles, and research hotspots.

    METHODS: The research datasets were acquired from the Scopus database. The search terms used were 'reward' AND 'human' AND 'diffusion imaging' OR 'diffusion tensor imaging' OR 'diffusion MRI' OR 'diffusion-weighted imaging' OR 'tractography' in the abstract, article title and keywords. A total of 336 publications were analysed using Harzing's Publish or Perish and VOSviewer software.

    RESULTS: The results revealed an upward trend in the number of publications with the highest number of articles in 2020 and 2022. Most publications were limited to countries, authors, and institutions in the USA, China and Europe. Bracht, Coenen, Wiest, Federspiel and Feng were among the top authors from Switzerland, Germany and the UK. Neuroimage, Neuroimage Clinical, Frontiers in Human Neuroscience, Human Brain Mapping, and the Journal of Neuroscience were the top journals. Among the top articles, six were reviews and four were original articles, while the top keywords in human reward research were 'diffusion MRI', 'adolescence', 'depression' and 'reward-related brain areas'.

    CONCLUSION: These findings may serve as researchers' references to find collaborative authors, relevant journals, cooperative countries/institutions, and hot topics related to dMRI and reward research.

  13. Law ZK, Tan HJ, Chin SP, Wong CY, Wan Yahya WNN, Muda AS, et al.
    Cytotherapy, 2021 Sep;23(9):833-840.
    PMID: 33992536 DOI: 10.1016/j.jcyt.2021.03.005
    BACKGROUND AIMS: Mesenchymal stromal cells (MSCs) are characterized by paracrine and immunomodulatory functions capable of changing the microenvironment of damaged brain tissue toward a more regenerative and less inflammatory milieu. The authors conducted a phase 2, single-center, assessor-blinded randomized controlled trial to investigate the safety and efficacy of intravenous autologous bone marrow-derived MSCs (BMMSCs) in patients with subacute middle cerebral artery (MCA) infarct.

    METHODS: Patients aged 30-75 years who had severe ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score of 10-35) involving the MCA territory were recruited within 2 months of stroke onset. Using permuted block randomization, patients were assigned to receive 2 million BMMSCs per kilogram of body weight (treatment group) or standard medical care (control group). The primary outcomes were the NIHSS, modified Rankin Scale (mRS), Barthel Index (BI) and total infarct volume on brain magnetic resonance imaging (MRI) at 12 months. All outcome assessments were performed by blinded assessors. Per protocol, analyses were performed for between-group comparisons.

    RESULTS: Seventeen patients were recruited. Nine were assigned to the treatment group, and eight were controls. All patients were severely disabled following their MCA infarct (median mRS = 4.0 [4.0-5.0], BI = 5.0 [5.0-25.0], NIHSS = 16.0 [11.5-21.0]). The baseline infarct volume on the MRI was larger in the treatment group (median, 71.7 [30.5-101.7] mL versus 26.7 [12.9-75.3] mL, P = 0.10). There were no between-group differences in median NIHSS score (7.0 versus 6.0, P = 0.96), mRS (2.0 versus 3.0, P = 0.38) or BI (95.0 versus 67.5, P = 0.33) at 12 months. At 12 months, there was significant improvement in absolute change in median infarct volume, but not in total infarct volume, from baseline in the treatment group (P = 0.027). No treatment-related adverse effects occurred in the BMMSC group.

    CONCLUSIONS: Intravenous infusion of BMMSCs in patients with subacute MCA infarct was safe and well tolerated. Although there was no neurological recovery or functional outcome improvement at 12 months, there was improvement in absolute change in median infarct volume in the treatment group. Larger, well-designed studies are warranted to confirm this and the efficacy of BMMSCs in ischemic stroke.

  14. Markby J, Shilton S, Sem X, Chan HK, Md Said R, Siva S, et al.
    BMJ Open, 2021 Dec 24;11(12):e055142.
    PMID: 34952885 DOI: 10.1136/bmjopen-2021-055142
    INTRODUCTION: To achieve the elimination of hepatitis C virus (HCV), substantial scale-up in access to testing and treatment is needed. This will require innovation and simplification of the care pathway, through decentralisation of testing and treatment to primary care settings and task-shifting to non-specialists. The objective of this study was to evaluate the feasibility and effectiveness of decentralisation of HCV testing and treatment using rapid diagnostic tests (RDTs) in primary healthcare clinics (PHCs) among high-risk populations, with referral of seropositive patients for confirmatory viral load testing and treatment.

    METHODS: This observational study was conducted between December 2018 and October 2019 at 25 PHCs in three regions in Malaysia. Each PHC was linked to one or more hospitals, for referral of seropositive participants for confirmatory testing and pretreatment evaluation. Treatment was provided in PHCs for non-cirrhotic patients and at hospitals for cirrhotic patients.

    RESULTS: During the study period, a total of 15 366 adults were screened at the 25 PHCs, using RDTs for HCV antibodies. Of the 2020 (13.2%) HCV antibody-positive participants, 1481/2020 (73.3%) had a confirmatory viral load test, 1241/1481 (83.8%) were HCV RNA-positive, 991/1241 (79.9%) completed pretreatment assessment, 632/991 (63.8%) initiated treatment, 518/632 (82.0%) completed treatment, 352/518 (68.0%) were eligible for a sustained virological response (SVR) cure assessment, 209/352 (59.4%) had an SVR cure assessment, and SVR was achieved in 202/209 (96.7%) patients. A significantly higher proportion of patients referred to PHCs initiated treatment compared with those who had treatment initiated at hospitals (71.0% vs 48.8%, p<0.001).

    CONCLUSIONS: This study demonstrated the effectiveness and feasibility of a simplified decentralised HCV testing and treatment model in primary healthcare settings, targeting high-risk groups in Malaysia. There were good outcomes across most steps of the cascade of care when treatment was provided at PHCs compared with hospitals.

  15. Slik JW, Aiba S, Bastian M, Brearley FQ, Cannon CH, Eichhorn KA, et al.
    Proc Natl Acad Sci U S A, 2011 Jul 26;108(30):12343-7.
    PMID: 21746913 DOI: 10.1073/pnas.1103353108
    The marked biogeographic difference between western (Malay Peninsula and Sumatra) and eastern (Borneo) Sundaland is surprising given the long time that these areas have formed a single landmass. A dispersal barrier in the form of a dry savanna corridor during glacial maxima has been proposed to explain this disparity. However, the short duration of these dry savanna conditions make it an unlikely sole cause for the biogeographic pattern. An additional explanation might be related to the coarse sandy soils of central Sundaland. To test these two nonexclusive hypotheses, we performed a floristic cluster analysis based on 111 tree inventories from Peninsular Malaysia, Sumatra, and Borneo. We then identified the indicator genera for clusters that crossed the central Sundaland biogeographic boundary and those that did not cross and tested whether drought and coarse-soil tolerance of the indicator genera differed between them. We found 11 terminal floristic clusters, 10 occurring in Borneo, 5 in Sumatra, and 3 in Peninsular Malaysia. Indicator taxa of clusters that occurred across Sundaland had significantly higher coarse-soil tolerance than did those from clusters that occurred east or west of central Sundaland. For drought tolerance, no such pattern was detected. These results strongly suggest that exposed sandy sea-bed soils acted as a dispersal barrier in central Sundaland. However, we could not confirm the presence of a savanna corridor. This finding makes it clear that proposed biogeographic explanations for plant and animal distributions within Sundaland, including possible migration routes for early humans, need to be reevaluated.
  16. Slik JW, Arroyo-Rodríguez V, Aiba S, Alvarez-Loayza P, Alves LF, Ashton P, et al.
    Proc Natl Acad Sci U S A, 2015 Jun 16;112(24):7472-7.
    PMID: 26034279 DOI: 10.1073/pnas.1423147112
    The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼ 19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼ 4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.
  17. Slik JWF, Franklin J, Arroyo-Rodríguez V, Field R, Aguilar S, Aguirre N, et al.
    Proc Natl Acad Sci U S A, 2018 02 20;115(8):1837-1842.
    PMID: 29432167 DOI: 10.1073/pnas.1714977115
    Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.
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