Displaying publications 1 - 20 of 318 in total

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  1. Assessing the spatial scale of synchrony in forest tree population dynamics
    Chisholm RA, Fung T, Anderson-Teixeira KJ, Bourg NA, Brockelman WY, Bunyavejchewin S, et al.
    Proc Biol Sci, 2024 Nov;291(2035):20240486.
    PMID: 39564678 DOI: 10.1098/rspb.2024.0486
    Populations of forest trees exhibit large temporal fluctuations, but little is known about the synchrony of these fluctuations across space, including their sign, magnitude, causes and characteristic scales. These have important implications for metapopulation persistence and theoretical community ecology. Using data from permanent forest plots spanning local, regional and global spatial scales, we measured spatial synchrony in tree population growth rates over sub-decadal and decadal timescales and explored the relationship of synchrony to geographical distance. Synchrony was high at local scales of less than 1 km, with estimated Pearson correlations of approximately 0.6-0.8 between species' population growth rates across pairs of quadrats. Synchrony decayed by approximately 17-44% with each order of magnitude increase in distance but was still detectably positive at distances of 100 km and beyond. Dispersal cannot explain observed large-scale synchrony because typical seed dispersal distances (<100 m) are far too short to couple the dynamics of distant forests on decadal timescales. We attribute the observed synchrony in forest dynamics primarily to the effect of spatially synchronous environmental drivers (the Moran effect), in particular climate, although pests, pathogens and anthropogenic drivers may play a role for some species.
    Matched MeSH terms: Population Dynamics*
  2. Population dynamics and ranging behaviours of provisioned silvered langur (Trachypithecus cristatus) in Peninsular Malaysia
    Mohd-Daut N, Matsuda I, Abidin KZ, Md-Zain BM
    Primates, 2021 Nov;62(6):1019-1029.
    PMID: 34486090 DOI: 10.1007/s10329-021-00934-6
    Tourists are attracted to the Bukit Melawati Kuala Selangor (BMKS) of Peninsular Malaysia, a small hill park, for both its status as a historical site and the free-ranging silvered langurs (Trachypithecus cristatus) that come for provisioning. We assessed the population trends and group sizes of T. cristatus over 10 years in the BMKS and examined their ranging patterns. Comparisons of observed populations between 2005 (190 individuals) and 2017 (193 individuals) revealed the stable demography and group sizes of the six T. cristatus groups in the BMKS. Based on a total of 185 location points of the six groups in 2017, their mean ranging area was 3.6 ha with a range of 0.86-6.93 ha with extensive spatial overlap. We also found a significant positive relationship between the six groups' ranges and group sizes in 2017. Additionally, qualitative ecological comparisons with a previous study on T. cristatus in 1965 (before provisioning) suggest that the artificial food supply in the study area could modify the population dynamics and socioecology of T. cristatus. The modifications might alter their range size and territoriality in the BMKS. Overall, we found that provisioning had negative effects on the ecology of T. cristatus in the BMKS. Therefore, modifying management policies, such as banning feeding and implementing educational programs, may contribute to their proper conservation.
    Matched MeSH terms: Population Dynamics
  3. Water and wastewater in developing countries: present reality and strategy for the future
    Ujang Z, Buckley C
    Water Sci Technol, 2002;46(9):1-9.
    PMID: 12448446
    This paper summarises the paper presentation sessions at the Conference, as well giving insights on the issues related to developing countries. It also discusses the present status of practice and research on water and wastewater management, and projected future scenario based not only on the papers presented in the Conference, but also on other sources. The strategy is presented to overcome many problems in developing countries such as rapid urbanization, industrialization, population growth, financial and institutional problems and, depleting water resources. The strategy consists of Integrated Urban Water Management (IUWM), cleaner industrial production, waste minimisation and financial arrangements.
    Matched MeSH terms: Population Dynamics*
  4. Fulltext Seasonal abundance of Aedes albopictus in selected urban and suburban areas in Penang, Malaysia
    Rozilawati H, Zairi J, Adanan CR
    Trop Biomed, 2007 Jun;24(1):83-94.
    PMID: 17568381 MyJurnal
    Ovitrap surveillance was conducted in a selected urban area and suburban area, ie. Taman Permai Indah(TPI) and Kampung Pasir Gebu (KPG) in Penang for 14 months. It was found that Aedes albopictus was the most abundant Aedes species in both study areas, even though a small percentage of Aedes aegypti and Culex quinquefasciatus were found to breed simultaneously in the same ovitrap. This study indicated that the main dengue vector was Ae. albopictus. A strong correlation was found between rainfall and egg population in both of the study sites (r = 0.982 and r = 0.918).
    Matched MeSH terms: Population Dynamics*
  5. A note on internal migration and regional growth trends in Peninsular Malaysia, 1957-1970
    Narayanan S
    Malay Econ Rev, 1978;23(2):53-60.
    PMID: 12262802
    Matched MeSH terms: Population Dynamics*
  6. Migrant-native socioeconomic differences in a major metropolitan area of Peninsular Malaysia: its implications on migration policy in a multiethnic society
    Soon L
    J Dev Areas, 1978;13(1):35-48.
    PMID: 12310729
    Matched MeSH terms: Population Dynamics*
  7. Internal migrants in Peninsular Malaysia
    Pryor RJ
    J Trop Geogr, 1978;46:61-75.
    PMID: 12262749
    Matched MeSH terms: Population Dynamics*
  8. A comparison of urban migration in Sarawak and the Philippines
    Sutlive V
    Urban anthropol, 1977;6(4):355-69.
    PMID: 12310786
    Matched MeSH terms: Population Dynamics*
  9. Dynamical behaviors and optimal harvesting of an intraguild prey-predator fishery model with Michaelis-Menten type predator harvesting
    Ang TK, Safuan HM
    Biosystems, 2021 Apr;202:104357.
    PMID: 33486091 DOI: 10.1016/j.biosystems.2021.104357
    The present paper discusses the dynamics and optimal harvesting of an intraguild prey-predator fishery model by incorporating the nonlinear Michaelis-Menten type of harvesting in predator. To our knowledge, there is limited literature working on Michaelis-Menten type of harvesting in a three species intraguild model with variable carrying capacity. The carrying capacity is proportional to the density of biotic resource. The existence of the possible equilibria has been studied along with the stability criteria. We consider the impact of predator fish harvesting as the bifurcation parameter to analyze the long time behavior of the proposed system. From the economic perspective, bionomic equilibrium of the system is studied and optimal harvesting policy is derived with the assistance of Pontryagin Maximum Principle. Finally, numerical results are presented to verify our analytical results. It is shown that in the bifurcation diagrams, the system can exhibit transcritical and Hopf bifurcations in the neighborhood of coexistence equilibrium at low and relatively high level of predator harvesting respectively. Interestingly, the system enters to a bistable region where both the coexistence and predator-free equilibria can be stable depending on the initial values. This bistable behavior might be novel to the existing literature that studied intraguild models with variable carrying capacity. The objective of this study is to derive the optimal threshold for the predator harvesting that gives maximum financial profit while sustaining the fishery resources.
    Matched MeSH terms: Population Dynamics*
  10. Fulltext Hunter-gatherer residential mobility and the marginal value of rainforest patches
    Venkataraman VV, Kraft TS, Dominy NJ, Endicott KM
    Proc Natl Acad Sci U S A, 2017 03 21;114(12):3097-3102.
    PMID: 28265058 DOI: 10.1073/pnas.1617542114
    The residential mobility patterns of modern hunter-gatherers broadly reflect local resource availability, but the proximate ecological and social forces that determine the timing of camp movements are poorly known. We tested the hypothesis that the timing of such moves maximizes foraging efficiency as hunter-gatherers move across the landscape. The marginal value theorem predicts when a group should depart a camp and its associated foraging area and move to another based on declining marginal return rates. This influential model has yet to be directly applied in a population of hunter-gatherers, primarily because the shape of gain curves (cumulative resource acquisition through time) and travel times between patches have been difficult to estimate in ethnographic settings. We tested the predictions of the marginal value theorem in the context of hunter-gatherer residential mobility using historical foraging data from nomadic, socially egalitarian Batek hunter-gatherers (n = 93 d across 11 residential camps) living in the tropical rainforests of Peninsular Malaysia. We characterized the gain functions for all resources acquired by the Batek at daily timescales and examined how patterns of individual foraging related to the emergent property of residential movements. Patterns of camp residence times conformed well with the predictions of the marginal value theorem, indicating that communal perceptions of resource depletion are closely linked to collective movement decisions. Despite (and perhaps because of) a protracted process of deliberation and argument about when to depart camps, Batek residential mobility seems to maximize group-level foraging efficiency.
    Matched MeSH terms: Population Dynamics*
  11. Fulltext Discrete-time predator-prey model with flip bifurcation and chaos control
    Khan AQ, Ahmad I, Alayachi HS, M Noorani MS, Khaliq A
    Math Biosci Eng, 2020 09 09;17(5):5944-5960.
    PMID: 33120584 DOI: 10.3934/mbe.2020317
    We explore the local dynamics, flip bifurcation, chaos control and existence of periodic point of the predator-prey model with Allee effect on the prey population in the interior of $\mathbb{R}^*{_+^2}$. Nu-merical simulations not only exhibit our results with the theoretical analysis but also show the complex dynamical behaviors, such as the period-2, 8, 11, 17, 20 and 22 orbits. Further, maximum Lyapunov exponents as well as fractal dimensions are also computed numerically to show the presence of chaotic behavior in the model under consideration.
    Matched MeSH terms: Population Dynamics
  12. Species description and distribution of Strombus (Mollusca, Strombidae) in Johor Straits and its surrounding areas
    Zaidi Che Cob, Aziz Arshad, Japar Sidik Bujang, Mazlan Abdul Ghaffar
    Sains Malaysiana, 2009;38.
    A total of 230 individuals of Strombus were sampled at various locations along the Johor Straits, Malaysia. There were four species of Strombus present in the study areas i.e. Strombus canarium Linnaeus, 1758; Strombus urceus Linnaeus, 1758; Strombus marginatus subspecies succinctus Linnaeus, 1767; Strombus marginatus subspecies robustus Sowerby, 1874; and Strombus vittatus subspecies vittatus Linnaeus, 1758. Strombus canarium was the most common, widely distributed and most abundant, followed by S. urceus, while the others were only rarely found. Among the species Strombus marginatus and Strombus vittatus were two new distribution records for the Johor Straits. Since all Strombus were traditionally harvested and consumed by the locals since long ago, further studies are needed particularly regarding the population dynamics and fishery of the harvested species.
    Matched MeSH terms: Population Dynamics
  13. Mathematical modeling and analysis of anemia during pregnancy and postpartum
    Mat Daud AA, Toh CQ, Saidun S
    Theory Biosci, 2021 Feb;140(1):87-95.
    PMID: 33590451 DOI: 10.1007/s12064-020-00334-2
    Anemia is a significant public health problem worldwide especially among pregnant women in low- and middle-income countries. In this study, a mathematical model of the population dynamics of anemia during pregnancy and postpartum is constructed. In the modeling process, four independent variables have been considered: (1) the numbers of nonpregnant nonanemic women, (2) anemic nonpregnant women, (3) anemic pregnant or postpartum women and (4) anemic pregnant or postpartum women with complications. The mathematical model is governed by a system of first-order ordinary differential equations. The stability analysis of the model is conducted using Routh-Hurwitz criteria. There is one nonnegative equilibrium point which is asymptotically stable. The equilibrium point obtained indicates the influential parameters that can be controlled to minimize the number of patients at each stage. The proposed model can be employed to forecast the future incidence and prevalence of the disease and appraise intervention programs.
    Matched MeSH terms: Population Dynamics
  14. Fulltext Out of Borneo: biogeography, phylogeny and divergence date estimates of Artocarpus (Moraceae)
    Williams EW, Gardner EM, Harris R, Chaveerach A, Pereira JT, Zerega NJ
    Ann Bot, 2017 03 01;119(4):611-627.
    PMID: 28073771 DOI: 10.1093/aob/mcw249
    Background and Aims: The breadfruit genus ( Artocarpus , Moraceae) includes valuable underutilized fruit tree crops with a centre of diversity in Southeast Asia. It belongs to the monophyletic tribe Artocarpeae, whose only other members include two small neotropical genera. This study aimed to reconstruct the phylogeny, estimate divergence dates and infer ancestral ranges of Artocarpeae, especially Artocarpus , to better understand spatial and temporal evolutionary relationships and dispersal patterns in a geologically complex region.

    Methods: To investigate the phylogeny and biogeography of Artocarpeae, this study used Bayesian and maximum likelihood approaches to analyze DNA sequences from six plastid and two nuclear regions from 75% of Artocarpus species, both neotropical Artocarpeae genera, and members of all other Moraceae tribes. Six fossil-based calibrations within the Moraceae family were used to infer divergence times. Ancestral areas and estimated dispersal events were also inferred.

    Key Results: Artocarpeae, Artocarpus and four monophyletic Artocarpus subgenera were well supported. A late Cretaceous origin of the Artocarpeae tribe in the Americas is inferred, followed by Eocene radiation of Artocarpus in Asia, with the greatest diversification occurring during the Miocene. Borneo is reconstructed as the ancestral range of Artocarpus , with dozens of independent in situ diversification events inferred there, as well as dispersal events to other regions of Southeast Asia. Dispersal pathways of Artocarpus and its ancestors are proposed.

    Conclusions: Borneo was central in the diversification of the genus Artocarpus and probably served as the centre from which species dispersed and diversified in several directions. The greatest amount of diversification is inferred to have occurred during the Miocene, when sea levels fluctuated and land connections frequently existed between Borneo, mainland Asia, Sumatra and Java. Many species found in these areas have extant overlapping ranges, suggesting that sympatric speciation may have occurred. By contrast, Artocarpus diversity east of Borneo (where many of the islands have no historical connections to the landmasses of the Sunda and Sahul shelves) is unique and probably the product of over water long-distance dispersal events and subsequent diversification in allopatry. This work represents the most comprehensive Artocarpus phylogeny and biogeography study to date and supports Borneo as an evolutionary biodiversity hotspot.

    Matched MeSH terms: Population Dynamics
  15. Fulltext Population genetics and demography of the coral-killing cyanobacteriosponge, Terpios hoshinota, in the Indo-West Pacific
    Chow SW, Keshavmurthy S, Reimer JD, de Voogd N, Huang H, Wang JT, et al.
    PeerJ, 2022;10:e13451.
    PMID: 35669953 DOI: 10.7717/peerj.13451
    The first occurrence of the cyanobacteriosponge Terpios hoshinota was reported from coral reefs in Guam in 1973, but was only formally described in 1993. Since then, the invasive behavior of this encrusting, coral-killing sponge has been observed in many coral reefs in the West Pacific. From 2015, its occurrence has expanded westward to the Indian Ocean. Although many studies have investigated the morphology, ecology, and symbiotic cyanobacteria of this sponge, little is known of its population genetics and demography. In this study, a mitochondrial cytochrome oxidase I (COI) fragment and nuclear ribosomal internal transcribed spacer 2 (ITS2) were sequenced to reveal the genetic variation of T. hoshinota collected from 11 marine ecoregions throughout the Indo-West Pacific. Both of the statistical parsimony networks based on the COI and nuclear ITS2 were dominated by a common haplotype. Pairwise F ST and Isolation-by-distance by Mantel test of ITS2 showed moderate gene flow existed among most populations in the marine ecoregions of West Pacific, Coral Triangle, and Eastern Indian Ocean, but with a restricted gene flow between these regions and Maldives in the Central Indian Ocean. Demographic analyses of most T. hoshinota populations were consistent with the mutation-drift equilibrium, except for the Sulawesi Sea and Maldives, which showed bottlenecks following recent expansion. Our results suggest that while long-range dispersal might explain the capability of T. hoshinota to spread in the IWP, stable population demography might account for the long-term persistence of T. hoshinota outbreaks on local reefs.
    Matched MeSH terms: Population Dynamics
  16. Prehistoric human migration between Sundaland and South Asia was driven by sea-level rise
    Kim HL, Li T, Kalsi N, Nguyen HTT, Shaw TA, Ang KC, et al.
    Commun Biol, 2023 Feb 04;6(1):150.
    PMID: 36739308 DOI: 10.1038/s42003-023-04510-0
    Rapid sea-level rise between the Last Glacial Maximum (LGM) and the mid-Holocene transformed the Southeast Asian coastal landscape, but the impact on human demography remains unclear. Here, we create a paleogeographic map, focusing on sea-level changes during the period spanning the LGM to the present-day and infer the human population history in Southeast and South Asia using 763 high-coverage whole-genome sequencing datasets from 59 ethnic groups. We show that sea-level rise, in particular meltwater pulses 1 A (MWP1A, ~14,500-14,000 years ago) and 1B (MWP1B, ~11,500-11,000 years ago), reduced land area by over 50% since the LGM, resulting in segregation of local human populations. Following periods of rapid sea-level rises, population pressure drove the migration of Malaysian Negritos into South Asia. Integrated paleogeographic and population genomic analysis demonstrates the earliest documented instance of forced human migration driven by sea-level rise.
    Matched MeSH terms: Population Dynamics
  17. Fulltext Island Biogeography Revisited: Museomics Reveals Affinities of Shelf Island Birds Determined by Bathymetry and Paleo-Rivers, Not by Distance to Mainland
    Garg KM, Chattopadhyay B, Cros E, Tomassi S, Benedick S, Edwards DP, et al.
    Mol Biol Evol, 2022 Jan 07;39(1).
    PMID: 34893875 DOI: 10.1093/molbev/msab340
    Island biogeography is one of the most powerful subdisciplines of ecology: its mathematical predictions that island size and distance to mainland determine diversity have withstood the test of time. A key question is whether these predictions follow at a population-genomic level. Using rigorous ancient-DNA protocols, we retrieved approximately 1,000 genomic markers from approximately 100 historic specimens of two Southeast Asian songbird complexes from across the Sunda Shelf archipelago collected 1893-1957. We show that the genetic affinities of populations on small shelf islands defy the predictions of geographic distance and appear governed by Earth-historic factors including the position of terrestrial barriers (paleo-rivers) and persistence of corridors (Quaternary land bridges). Our analyses suggest that classic island-biogeographic predictors may not hold well for population-genomic dynamics on the thousands of shelf islands across the globe, which are exposed to dynamic changes in land distribution during Quaternary climate change.
    Matched MeSH terms: Population Dynamics
  18. The determinants of infant mortality in Malaysia: a graphical chain modelling approach
    Mohamed WN, Diamond I, Smith PW
    J R Stat Soc Ser A Stat Soc, 1998;161(3):349-66.
    PMID: 12348725
    "A graphical chain modelling approach is used to study the determinants of neonatal and post-neonatal mortality in Malaysia. This approach provides an easily interpretable empirical description and illustrates explicitly the conditional independence structure between each pair of variables. The interpretation can be read directly from a mathematical graph. Besides examining the direct association of each determinant on mortality, we also examine the effects of socio-economic determinants on intermediate determinants to understand the pathways through which the socioeconomic determinants affect the chance of mortality. The data anlaysed come from the second Malaysian Family Life Survey, fielded between August 1988 and January 1989. "
    Matched MeSH terms: Population Dynamics*
  19. "Population is key factor in environmental degradation," Parliamentarian conference on ocean life declares
    Asian Forum Newsl, 1995 Oct-Dec.
    PMID: 12320069
    Matched MeSH terms: Population Dynamics*
  20. Internal migration in a rapidly developing country: the case of Peninsular Malaysia
    Chan KE
    Malays J Trop Geogr, 1994 Dec;25(2):69-77.
    PMID: 12291229
    "This paper discusses the patterns and trends in internal territorial mobility in Peninsular Malaysia from 1957 [to] the 1980s, focussing specially on the period of the 1980s." Data are from Peninsular Malaysian Labour Force Migration Sample Surveys.
    Matched MeSH terms: Population Dynamics*
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