Demography and Socio-Economic Aspects on Irrigated Smallholder Agricultural Enterprises and Their Association with the Cultivation of Maize (Zea mays L.) as a Selected Field Crop

The purpose of this study is to correlate demography and socio-economic aspects at Irrigated Smallholder Agricultural Enterprises and their association with the Cultivation of Maize in order to determine its positive impacts at irrigated smallholders’ agricultural entrepreneurs’ household. Chi-square test was used as descriptive analysis method. The Fischer Exact tests were employed to test demography (gender, age, education, and income) in winter and summer production season of irrigated smallholder agricultural enterprises and their association with the cultivation of selected field crop (i.e. maize). The results show that gender results were not being statistically significant, as measured by the Phi measure of effect size, φ = 0.149, p = 0.011, and φ = 0.05, p = 0.392 in summer. As far as age is concern, it appears to be a statistically significant association between cultivating maize and age in winter, φ = 0.046, p = 0.730 in winter and φ = 0.172, p = 0.013. Education winter result not being statistically significant, the effect size showed a weak association, as measured by the Phi measure of effect size, φ = 0.112, p = 0.305 and φ = 0.035, p = 0.948 in summer. Income result not being statistically significant, as measured by the Phi measure of effect size, φ = 0.049, p = 0.399 and φ = 0.081, p = 0.166 in summer. In conclusion, the study shows that the development of best management practices must be based on a comprehensive analysis of the livelihoods and irrigated smallholder agricultural enterprise farming styles of participating irrigated smallholder agricultural entrepreneurs.

Demography of the threatened endemic shrub, Arbutus pavarii,in the Al-Akhdar mountainous landscape of Libya

We sampled twenty populations of the vulnera- ble endemic shrub or tree, Arbutus pavarii Pampan., at different elevations and aspects within the A1-Akhdar mountainous region of Libya. Our sampling sites were at elevations ranging from 285 to 738 m above sea level, and several different habitats： vallies （locally known as wadis）, north- and south-facing slopes, and mountaintops. All individuals within each quadrat were studied. Population size and structure, and plant functional traits were assessed. None of the populations had a stable distribution of size classes. Some consisted mostly of small plants, with little or no fruit production; others consisted only of mid-sized and large plants, with high fruit production, but no juvenile recruitment. There was a significant increase in percent cover with increasing elevation; reproductive output （the number of fruits per branch and total number of fruits per individual） also generally increased with elevation. In some of these populations the lack of recruitment, and in others the failure to produce fruit, together constituted serious demographic threats. In light of these results, recommen- dations are made for conservation of this vulnerable endemic species.

Landscape alteration affects the demography of an endangered avian predator by reducing the habitat quality

Habitat transformation is identified as major threat to biodiversity loss globally,affecting threatened raptors.Changes in land use can alter the abundance and distribution of birds of prey by affecting habitat availability and quality.In this study,we used multivariate analyses to investigate the effect of habitat alteration on the demography of a declining Eastern Imperial Eagle(Aqufla heliaca),making assumptions for future population trajectories.We used the Generalized Linear Mixed Models with Poisson distribution and Log link function,searching a relationship between the demographic parameters and the landscape structure and possible effects of fragmentation.In our study area,habitat change affected dramatically permanent grasslands,shrinking their availability.As we expected,the share of grasslands in eagles’territories significantly affected occupancy rate,but not productivity and breeding frequency.We found that occupancy rate decreased significantly,while productivity and breeding frequency showed no trend.Modeling the effect of habitat alteration on Eastern Imperial Eagle demography,we found out that territory quality was a more powerful factor driving the response of a top predator to the alteration of favorite foraging habitats.Only the habitat quality in source territories had a significant positive effect on eagle productivity.We found that simple rules to predict adverse agricultural impact on territory abandonment or breeding productivity of a top predator were not reliable.Our results could be used for planning conservation of other large territorial raptors,facing the same type of threat.

Expected adult lifespan in tropical trees: Long-term matrix demography in a large plot

Background: Documenting the entire lifetime of long-lived organisms requires splicing together short-term observations. Matrix demography provides a tool to calculate lifetime statistics, but large samples from juvenile to adult are needed, and few such studies have been done in tropical trees because high species diversity limits sample sizes. The 50-ha plot at Barro Colorado in Panama was designed to provide large samples, and with 30years of censuses, accurate population matrices can be constructed.Methods: In 31 abundant species, I divided all individuals≥1 cm dbh into 4 or 5 size class in each of seven censuses. Movements of stems between size classes over two censuses are termed transitions, and I constructed complete transition matrices for each species. From the matrices, I derived analytic solutions for lifetime demographic statistics. Expected adult lifespan from the sapling stage was the key statistic.Results: Expected adult lifespan from the sapling stage varied 100-fold over the 31 species, from 0.5 to 50 years,and maturation time varied from 19 to nearly 200 years. Species with the highest growth rates also had high death rates, and theoretical calculations of reproductive lifespan show that the fast-growing pioneer species have short expected adult lifespans relative to the average slow-growing, shade-tolerant species. Within the slowgrowth category, however, there was high variation in expected adult lifespan, and several shade-tolerant species under-performed the pioneers in terms of adult lifespan.Conclusions: Analytical solutions from population matrices allow theoretical analyses that integrate short-term growth records into lifespans of tropical trees. The analyses suggest that pioneer species must reproduce more successfully than shade-tolerant species to persist in the Barro Colorado forest. My next goal is to incorporate seed production and germination into lifetime matrix demography to test this hypothesis.

Demography and Conflicts in the Context of Israel/Palestine： Forecasts for the Future

In the context of historical Palestine, the Palestinian and Jewish demography are deeply embedded （Goldsheider, 1991; Freidlander, 2002）. The growth and structure of the populations are one of the most important tools for the control of the territory （Dahlan, 1989）. Jewish immigration was and is still considered as the single most important mean for the conquest of the land （Courbage, 2005）. Yet this is only a partial truth （Fargues, 2000）. Fertility, especially when it is natural at its peak or still very high is also a very significant asset, which is likely to reverse internal equilibrium among the different forces shaping the two societies （Courbage ＆ Todd, 2011; Ettinger, 2011）. Hence, Jews and Palestinians have embarked since decades into a demographic competition （Faraoune, personal communication, December 19, 1992; Anson ＆ Avinoam, 1996）, with this extraordinary result, that in a matter of a century （1948-2048） this small piece of land will have undergone the highest population growth on earth, equivalent to sub Saharan Africa （Faitelson, 2008; Courbage ＆ Fargues, 1997）. It is likely output is not less important to define the future nature of historical Palestine： one or two states （Baskin, 2005; Courbage, 2008）？ And if the two states solution is in effect, what kind of states would it be？ After presenting the recent trends of Palestinian demography in the context of historical Palestine since the first intifada and the aftermath of the second intifada, this essay will focus on future developments, i.e. the likely population dynamics of the Palestinian territory from 2011 until 2048, and of its different components, namely fertility. Palestinian population growth during the next four decades will be compared to that of the future Israeli population and the policy components of this differential population growth will be evaluated both in the context of historical Palestine and in the context of the Jewish State in its 1948 borders （Jews and Palestinians of 1948）. The most serious demographic challenges, （which are not those of an overall ＂equilibrium＂ between Palestinian and Jewish populations as very often claimed）, are very precisely delineated in the ground. These are, first, the question of the peopling of the settlements （Be-Tselem, 2002）. their population is likely to explode from 560,000 settlers now to 1.7 million in 2048, thanks to their extremely high fertility, low mortality, high immigration and ＂population momentum＂ （Central Bureau of Statistics, 2013; Courbage, 2006）. From 18% of the overall population of the West Bank they could reach 29% in 2048, a clear defiance to the possibility of statehood in Palestine. Besides, statehood in Palestine is also threatened by the fact that East-Jerusalem, the likely capital of the Palestinian state is also threatened by the expansionist demography of the Jewish settlers, both in the so-called ＂neighborhoods＂, those settlements close to Jerusalem but which are according to international law an integral part of the West Bank （annexed by Israel in 1967）, and inside the Old city. In Jerusalem, besides Jewish immigration to the neighborhoods from the densely and poor areas of West Jerusalem, fertility trends have now been reversed to advantage of the Jews as compared to the Palestinians in the Holy city （Della Pergola, 2001）. This presentation will deal also with the population trends of the Palestinian population from now on until 2048 （Dalen ＆ Petersen, 2004; Courbage, 1999）. Under the impact of a higher fertility, and a population momentum clearly to its benefit, the population of Gaza （all Palestinians） could approach the Palestinian population of the West Bank： 4.0 in Gaza, 4.3 in the WB （Clarens, 2011）. Yet, the slight majority in the West Bank comes from the Palestinians in Jerusalem, whose political status is still vague. A larger share of the Palestinian population living in the Gaza strip rather than in the West bank is probably not devoid of political implications. For the policy makers it is not easy to run against demographic trends, especially when they are largely guided and decided by the other State which shares the same land. Yet, it is of utmost importance to be fully aware of the likely evolution of the demographic landscape in Palestine and to prepare the demographic but mostly non-demographic policy measures to counterbalance their effects.

Incidence and Survivability of Acute Lymphocytic Leukemia Patients in the United States: Analysis of SEER Data Set from 2000-2019

The main goal of this research is to assess the impact of race, age at diagnosis, sex, and phenotype on the incidence and survivability of acute lymphocytic leukemia (ALL) among patients in the United States. By taking these factors into account, the study aims to explore how existing cancer registry data can aid in the early detection and effective treatment of ALL in patients. Our hypothesis was that statistically significant correlations exist between race, age at which patients were diagnosed, sex, and phenotype of the ALL patients, and their rate of incidence and survivability data were evaluated using SEER*Stat statistical software from National Cancer Institute. Analysis of the incidence data revealed that a higher prevalence of ALL was among the Caucasian population. The majority of ALL cases (59%) occurred in patients aged between 0 to 19 years at the time of diagnosis, and 56% of the affected individuals were male. The B-cell phenotype was predominantly associated with ALL cases (73%). When analyzing survivability data, it was observed that the 5-year survival rates slightly exceeded the 10-year survival rates for the respective demographics. Survivability rates of African Americans patients were the lowest compared to Caucasian, Asian, Pacific Islanders, Alaskan Native, Native Americans and others. Survivability rates progressively decreased for older patients. Moreover, this study investigated the typical treatment methods applied to ALL patients, mainly comprising chemotherapy, with occasional supplementation of radiation therapy as required. The study demonstrated the considerable efficacy of chemotherapy in enhancing patients’ chances of survival, while those who remained untreated faced a less favorable prognosis from the disease. Although a significant amount of data and information exists, this study can help doctors in the future by diagnosing patients with certain characteristics. It will further assist the health care professionals in screening potential patients and early detection of cases. This could also save the lives of elderly patients who have a higher mortality rate from this disease.

Effect of temperature on the demography of Galerucella birmanica （Coleoptera： Chrysomelidae）

Studies on the effect of temperature on the development of the water chestnut beetle, Galerucella birmanica Jacoby were carried out in the laboratory at seven different temperatures： 16 ℃, 19 ℃, 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃. The developmental time decreased with increase in temperature. The developmental time at 16 ℃, 19℃, 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃ was 96.60, 80.68, 58.96, 43.48, 35.03, 30.08 and 28.02 days for the period from egg hatching to adult emergence, respectively. The developmental threshold estimated for a generation by linear regression was 10.36℃. The fecundity per female at 22 ℃, 25 ℃, 28 ℃, 31 ℃ and 34 ℃ was 102.3, 134.5, 141.2, 130.1 and 116.2 eggs, respectively. Oviposition period ranged from 15.6 days at 22 ℃ to 8.6 days at 34 ℃. Hatchability of eggs was highest at 31 ℃ with 76.9% and lowest at 34 ℃ with 57.1%. The highest generation survival rate was 65.3% at 31 ℃, and the intrinsic rate of natural increase （rm） for G. birmanica was the highest at 34 ℃.

Comparative demography of Liriomyza sativae Blanchard （Diptera： Agromyzidae） on cucumber at seven constant temperatures

Reproduction and population parameters of vegetable leafminer, Liriomyza sativae Blanchard were measured on cucumber （Cucumis sativus L.） at seven constant temperatures （10, 15, 20, 25, 30, 35 and 40℃）. No eggs were found at 10℃ and flies died after exposure to 40℃. The significantly highest intrinsic rate of natural increase （rm）, net reproductive rate （R0） and finite rate of increase （λ） ofL. sativae were obtained at 25℃ as 0.196, 52.452, and 1.216, respectively. The above-mentioned parameters decreased at 15℃ and 135℃ and this reduction at 35℃ was strong. Doubling time （DT） varied significantly with temperature. The shortest doubling time was obtained at 25℃. Mean generation time （T） decreased significantly with increasing temperature between 15℃ and 35℃. Percentage of immature ages in the stable age distribution was more than 95% at all temperatures. Female longevity was greater than male at all temperatures. Liriomyza sativae lived for a long time at 15℃, whereas at 35℃ had lower survival rates. The effect of temperature on reproduction, especially the intrinsic rate of increase of L. sativae would be useful for predicting its longterm population fluctuation over several generations.

The Multistate Evolution Equation of Family Population and Some Family Demography Indexes

In this paper we build the multi-state evolution equation of family population to describe the women’s marital statuses, fertility statuses, parity statuses, the number of surviving children statuses, family marker statuses, etc. and the women statuses dynamic transition between different statuses is computed from age-specific transition probabilities. Also we build some family demography indexes.This work is supported by the Management Decision & Information System Research Laboratory.

Influence of CEO Demography on Entrepreneurial Orientation： The Moderating Role of Competitive Intensity

Although entrepreneurial orientation has been identified as a key facilitator of a firm＇s innovative behaviors, its antecedents, especially the determinant role of the business leader, have yet to be explored. Drawing on strategic leadership theory, which posits the role of CEO in determining a firm＇s strategic direction, we examined the influence of CEO demography, specifically age, tenure, and education, on a firm＇s entrepreneurial orientation. Based on a sample of 231 Chinese firms, we found firms with a CEO who was younger, higher educated, and with a shorter tenure on the job had a greater extent of entrepreneurial orientation. Moreover, the firm＇s competitive environment moderated these relationships.

Demographic changes in China’s forests from 1998 to 2018

Background: Tree demography is an essential indicator of various forest ecosystem services, and understanding its changes is critical for the sustainable management of forests. During the past four decades, China implemented unprecedented forest restoration projects, which altered tree demography by increasing the number of trees and introducing new species. However, it remains unclear how species composition has changed in China in response to the past forest restoration and demographical processes.Methods: We applied Forest Stability Index(FSI) and the relative change of FSI(%FSI) to describe the population dynamics of tree species and structure in China since 1998, using field-survey data collected from over 200,000plot-records from the 6th to 9th National Forest Inventories(NFIs).Results: The overall populations of both natural and planted forests have grown rapidly from 1998 to 2018, while the range of changes in the relative tree density was more variable for natural forests(ranging from-8.53% to42.46%) than for planted forests(ranging from-1.01% to 13.31%). The populations declined only in some of the tree species, including Betula platyphylla, Ulmus pumila, and Robinia pseudoacacia. In contrast, the populations of trees in the largest size-class either remained stable or expanded.Conclusions: Tree density of China?s forests(both natural and planted forests) generally expanded and the overall populations increased in most size classes, with greater increases occurred in planted forests. In contrasting to the global decline trends of large diameter trees, here we found no apparent decline for trees in the largest size-class in China, highlighting China?s success in improving forest health and forest adaptations to climate change. We advocate for more studies to reveal the mechanisms of the changes in tree demography, which will help to improve forest ecosystem services such as the carbon sequestration capacity.

Demographic characteristics of patients who underwent anterior cruciate ligament reconstruction at a tertiary care hospital in India

BACKGROUND Anterior cruciate ligament(ACL)tears are common sports-related injuries.Their incidence is not the same either for all the sports or for the same sport across various nations.This information is maintained by many sports leagues in their registries.However,very few nationwide registries exist for such injuries.This study is carried out to know the demographic characteristics of patients who underwent ACL reconstruction at our hospital in India.AIM To know the demographic characteristics of patients who underwent ACL reconstruction at a tertiary care hospital in India.METHODS All the patients who underwent ACL reconstruction from January 2020 to December 2021 were retrospectively studied.Patients with multi-ligament injuries or a history of previous knee surgery were excluded.The patients’history was obtained from the hospital records,they were interviewed telephonically,and online questionnaires were given.Their demographic data was analyzed and compared to the existing literature.RESULTS A total of 124 patients were operated on for ACL reconstruction during this period.The mean age of the patients was 27.97 years.One hundred and thirteen patients(91.1%)were male and 11(8.9%)were female.The majority of the patients(47.6%)sustained this injury by road traffic accidents(RTA)followed by sportsrelated injuries(39.5%).The commonest presenting complaint was giving way of the knee in 118 patients(95.2%).The mean duration from the injury to the first hospital visit among the patients was 290.1 d.The mean duration from the injury to surgery was 421.8 d.CONCLUSION ACL patients’demography is different in developing nations as compared to the developed world.RTA are the leading cause of ACL injuries and are followed by recreational sports as a cause.There is delayed access to healthcare leading to delayed diagnosis as well as even greater time to surgery.This,in turn,leads to poorer prognosis and longer rehabilitation.National registries for developing nations are the need of the hour due to the different demographics of ACL injuries in developing countries.

Correlates of Self-Assessed Wellness

Background: This study was concerned with correlates of self-assessed health and wellness on ten dimensions including emotional, financial and physical health. All 10 self-ratings loaded on one factor with high internal reliability. Method: In all 506 adult participants, completed short measures of the bright side, Big Five traits (TIPI) and a short measure of the dark side, personality disorders (PID-5-BF). Results: Correlations and regressions suggested that wellness was related to sex, education and religious beliefs as well as four of five bright- and dark-side traits. Being Sanguine was most positively, and Choleric most negatively, associated with subjective wellness. Detachment and Negative Affect were the highest dark-side correlates. The final regression suggested that over a third of the variance in subjective wellness could be explained by four bright- and two dark-side factors. Conclusions: Personality factors, especially instability and negative affectivity, play a crucial role in all aspects of wellness. Implications and limitations are acknowledged.

Monitoring trends and determinants of type 1 diabetes in geographically-determined populations

Speculations are rife as to the exact aetiology of Type 1 diabetes mellitus,It is suggested that viruses and other agents precipitate this condition,induce vulnerability and the consequential development of adverse infectious disorders,The disease incidence is increasing exponentially in geographically-determined precincts.It is a chronic,autoimmune metabolic disorder characterized by expansively deranged pancreatic beta-cells,insulin deficiency and hyperglycaemia.Certain environmental elements trigger the autoimmune pathways in genetically susceptible children and adolescents.Globally,diabetes is the most common chronic condition.Studies indicate that comorbidities,syndemics,specific patient status,exclusive treatment modalities,and consistent monitoring of blood glucose levels are critical for type 1 diabetes management.Type 1 diabetes is relatively less common than type 2 diabetes,but it poses greater morbidity and mortality than the latter.Research tends to determine the spatiotemporal variations of the disease,whether its incidence is increasing globally or restricted to a select population,and to estimate the magnitude of the alteration in incidence.Type 1 diabetes can pre-exist and remain undiagnosed in patients.It tends to worsen in comorbid states.Competent objective testing measures are pertinent for evaluation,appropriate and well-timed management of childhood type 1 diabetes for significant improvement in healthcare.Management of the disease using insulin or insulin analogues may induce side effects in the form of acute hypoglycemic episodes,central nervous system derangement,dementia,aggravated morbidity or mortality.Consistent self-monitoring blood glucose(SMBG)tool facilitates adjustments of timely insulin dose.In non-industrialised countries and vulnerable populations,latent constraints have revolved around the choice of,and access to medicinal drugs and high-tech systems in the prime management of type 1 diabetes and its sequelae.

Celiac disease:Prevalence,diagnosis,pathogenesis and treatment

Celiac disease(CD) is one of the most common diseases,resulting from both environmental(gluten) and genetic factors [human leukocyte antigen(HLA) and nonHLA genes].The prevalence of CD has been estimated to approximate 0.5%-1% in different parts of the world.However,the population with diabetes,autoimmune disorder or relatives of CD individuals have even higher risk for the development of CD,at least in part,because of shared HLA typing.Gliadin gains access to the basal surface of the epithelium,and interact directly with the immune system,via both trans-and para-cellular routes.From a diagnostic perspective,symptoms may be viewed as either "typical" or "atypical".In both positive serological screening results suggestive of CD,should lead to small bowel biopsy followed by a favourable clinical and serological response to the gluten-free diet(GFD) to confirm the diagnosis.Positive anti-tissue transglutaminase antibody or antiendomysial antibody during the clinical course helps to confirm the diagnosis of CD because of their over 99% specificities when small bowel villous atrophy is present on biopsy.Currently,the only treatment available for CD individuals is a strict life-long GFD.A greater understanding of the pathogenesis of CD allows alternative future CD treatments to hydrolyse toxic gliadin peptide,prevent toxic gliadin peptide absorption,blockage of selective deamidation of specific glutamine residues by tissue,restore immune tolerance towards gluten,modulation of immune response to dietary gliadin,and restoration of intestinal architecture.

Genetic diversity and structure of Rhododendron meddianum,a plant species with extremely small populations

Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations.In this study,we used double digest restriction-siteassociated DNA sequencing(ddRAD)technology to assess the genetic diversity,genetic structure and demographic history of the three extant populations of R.meddianum.Analysis of SNPs indicated that R.meddianum populations have a high genetic diversity(p?0.0772±0.0024,HE?0.0742±0.002).Both FST values(0.1582e0.2388)and AMOVA showed a moderate genetic differentiation among the R.meddianum populations.Meanwhile,STRUCTURE,PCoA and NJ trees indicated that the R.meddianum samples were clustered into three distinct genetic groups.Using the stairway plot,we found that R.meddianum underwent a population bottleneck about 70,000 years ago.Furthermore,demographic models of R.meddianum and its relative,Rhododendron cyanocarpum,revealed that these species diverged about 3.05(2.21e5.03)million years ago.This divergence may have been caused by environmental changes that occurred after the late Pliocene,e.g.,the Asian winter monsoon intensified,leading to a drier climate.Based on these findings,we recommend that R.meddianum be conserved through in situ,ex situ approaches and that its seeds be collected for germplasm.

Population genetic studies in the genomic sequencing era

Recent advances in high-throughput sequencing technologies have revolutionized the field of population genetics. Data now routinely contain genomic level polymorphism information, and the low cost of DNA sequencing enables researchers to investigate tens of thousands of subjects at a time. This provides an unprecedented opportunity to address fundamental evolutionary questions, while posing challenges on traditional population genetic theories and methods. This review provides an overview of the recent methodological developments in the field of population genetics, specifically methods used to infer ancient population history and investigate natural selection using large-sample, large-scale genetic data. Several open questions are also discussed at the end of the review.

Epidemiological and demographic study of acute animal biting in Abdanan County,Ilam Province,Western Iran

Objective: To determine the incidence, epidemiology and demography of acute animal bites referred to Abdanan health centers in the years 2009 to 2013. Methods: This study was a descriptive analytical research. Questionnaires for each case of acute animal bite was completed. Data about age, gender, kind of animal, residency, site of bite, etc taken from Abdanan health centers were analyzed. Data were analyzed in SPSS by using descriptive statistics. Results: Total number of exposed persons to acute animal bites was reported 67 in 2009 and 69 in 2013. The average incidence rate was 1.2 per 1 000 population. Bites were frequent among the age group of 20-30 years. Most of the cases were self-employment. Around 83.8% of cases were bitten by dogs. Of total 309 studied patients, 73.8% were male. Feet (71.5%) and hands (22.7%) were the most common body part affected. About 53.1% of cases were in rural population. Conclusions: Dogs seems to play a very important role in the epidemiology of rabies in Abdanan, Iran. No cases of human rabies were observed in our study. This may be because of increasing public awareness and the upgrading of health and treatment centers, all of which in study region provide post-exposure anti-rabies treatment including vaccination, immunoglobulin and wound washing.

Spatiotemporal Trends and Ecological Determinants in Population by Elevation in China Since 1990

It is very important to understand the ecological and socio-economic factors in population distribution and their changes over time for the compilation of regional development planning and the guidance of rational population flow.Using surface-based population data for China from 1990 to 2015,the national distribution and dynamics of the human population by elevation are quantified based on 1-km cell-size gridded distribution datasets and 1-km cell-size DEM(digital elevation model).A geographical detector model is used to quantitatively analyze the dominant role of natural geographical factors,such as topography and climate,on the spatial distribution of population.Results show that:1)the population size and density decrease rapidly with elevation below 1000 m above the sea level,and the gap in population density between low-altitude areas and high-altitude areas increases with time because of the continuous growth of population density in low-altitude areas;2)the distribution of the population can be divided into five steps according to integrated population density(IPD),in proportions of 43∶35∶21∶1∶0,and that these proportions have remained stable over the last 25 yr;3)the basic pattern of population spatial distribution is determined by natural geographical environment factors,such as topography,climate,geomorphology,and their interactions;and 4)the development of society and the economy are the driving forces for the dynamic change in the population distribution during the study period,with the distribution pattern and dynamics of population by altitude in China providing a comprehensive reflection of various geographical elements on different spatial scales.

Phylogeography of the Phrynocephalus vlangalii Species Complex in the Upper Reaches of the Yellow River Inferred from mtDNA ND4-tRNA^(LEU) Segments

The Ching Hai Toad-headed Agama(Phrynocephalus vlangalii) complex is a small toad-headed viviparous lizard that is endemic to the Qinghai-Tibetan Plateau. A fragment of mtDNA ND4-tRNALEU from 189 samples in 26 populations was used to infer the phylogeographic history of this species complex in the upper reaches of the Yellow River. Phylogenetic analyses revealed that P. vlangalii and another proposed species(P. putjatia) do not form a monophyletic mtDNA clade,which in contrast with a previous study,includes P. theobaldi and P. forsythii. Lineage diversification occurred in the Middle Pleistocene for P. vlangali(ca. 0.95 Ma) and in the Early Pleistocene for P. putjatia(ca. 1.78 Ma). The uplift of the A’nyemaqen Mountains and glaciations since the mid-late Pleistocene,especially during the Kunlun Glaciation,are considered to have promoted the allopartric divergence of P. vlangalii. The diversification of P. putjatia may be triggered by the tectonic movement in the Huangshui River valley during the C phase of Qingzang Movement. Subsequently,the glacial climate throughout the Pleistocene may have continued to impede the gene flow of P. putjatia,eventually resulting in the genetic divergence of P. putjatia in the allopatric regions. Demographic estimates revealed weak population expansion in one lineage of P. vlangalii(A2,the Qaidam Basin lineage) and one lineage of P. putjatia(B2,the north Qinghai Lake lineage) after approximately 42 000 years before present. However,constant population size through time was inferred for two lineages(A1 and B1),the source of Yellow River lineage of P. vlangalii and the southeast of Qinghai Lake lineage of P. putjatia,possibly due to stable populations persisting in areas unaffected by glacial advances. Our results also suggest: 1) at least four differentiated lineages of P. vlangalii complex may have evolved allopatrically in different regions during the Pleistocene glaciation events; 2) in support of several recent studies,P. putjatia is a valid species,having a more wide distribution than previously considered; and 3) a hypothesis referring to P. v. hongyuanensis,inhabiting in the source region of the Yellow River,being synonymous with P. v. pylozwi is supported.