Effects of ocean acidification on population dynamics and community structure of crustose coralline algae

Calcification and growth of crustose coralline algae (CCA) are affected by elevated seawater pCO2 and associated changes in carbonate chemistry. However, the effects of ocean acidification (OA) on population and community-level responses of CCA have barely been investigated. We explored changes in community structure and population dynamics (size structure and reproduction) of CCA in response to OA. Recruited from an experimental flow-through system, CCA settled onto the walls of plastic aquaria and developed under exposure to one of three pCO2 treatments (control [present day, 389±6 ppm CO2], medium [753±11 ppm], and high [1267±19 ppm]). Elevated pCO2 reduced total CCA abundance and affected community structure, in particular the density of the dominant species Pneophyllum sp. and Porolithon onkodes. Meanwhile, the relative abundance of P. onkodes declined from 24% under control CO2 to 8.3% in high CO2 (65% change), while the relative abundance of Pneophyllum sp. remained constant. Population size structure of P. onkodes differed significantly across treatments, with fewer larger individuals under high CO2. In contrast, the population size structure and number of reproductive structures (conceptacles) per crust of Pneophyllum sp. was similar across treatments. The difference in the magnitude of the response of species abundance and population size structure between species may have the potential to induce species composition changes in the future. These results demonstrate that the impacts of OA on key coral reef builders go beyond declines in calcification and growth, and suggest important changes to aspects of population dynamics and community ecology.

Population dynamics, demographic stochasticity, and the evolution of cooperation

A basic evolutionary problem posed by the Iterated Prisoner’s Dilemma game is to understand when the paradigmatic cooperative strategy Tit-for-Tat can invade a population of pure defectors. Deterministically, this is impossible. We consider the role of demographic stochasticity by embedding the Iterated Prisoner’s Dilemma into a population dynamic framework. Tit-for-Tat can invade a population of defectors when their dynamics exhibit short episodes of high population densities with subsequent crashes and long low density periods with strong genetic drift. Such dynamics tend to have reddened power spectra and temporal distributions of population size that are asymmetric and skewed toward low densities. The results indicate that ecological dynamics are important for evolutionary shifts between adaptive peaks.

Population genetics of Ice Age brown bears

The Pleistocene was a dynamic period for Holarctic mammal species, complicated by episodes of glaciation, local extinctions, and intercontinental migration. The genetic consequences of these events are difficult to resolve from the study of present-day populations. To provide a direct view of population genetics in the late Pleistocene, we measured mitochondrial DNA sequence variation in seven permafrost-preserved brown bear (Ursus arctos) specimens, dated from 14,000 to 42,000 years ago. Approximately 36,000 years ago, the Beringian brown bear population had a higher genetic diversity than any extant North American population, but by 15,000 years ago genetic diversity appears similar to the modern day. The older, genetically diverse, Beringian population contained sequences from three clades now restricted to local regions within North America, indicating that current phylogeographic patterns may provide misleading data for evolutionary studies and conservation management. The late Pleistocene phylogeographic data also indicate possible colonization routes to areas south of the Cordilleran ice sheet.

The evolution of RNA viruses: A population genetics view

RNA viruses are excellent experimental models for studying evolution under the theoretical framework of population genetics. For a proper justification of this thesis we have introduced some properties of RNA viruses that are relevant for studying evolution. On the other hand, population genetics is a reductionistic theory of evolution. It does not consider or make simplistic assumptions on the transformation laws within and between genotypic and phenotypic spaces. However, such laws are minimized in the case of RNA viruses because the phenotypic space maps onto the genotypic space in a much more linear way than on higher DNA-based organisms. Under experimental conditions, we have tested the role of deleterious and beneficial mutations in the degree of adaptation of vesicular stomatitis virus (VSV), a nonsegmented virus of negative strand. We also have studied how effective population size, initial genetic variability in populations, and environmental heterogeneity shapes the impact of mutations in the evolution of vesicular stomatitis virus. Finally, in an integrative attempt, we discuss pros and cons of the quasispecies theory compared with classic population genetics models for haploid organisms to explain the evolution of RNA viruses.

Measuring ageing and the need for longer working lives in the EU. CEPS Working Document No. 417/February 2016 Wednesday, 24 February 2016

This study considers different ways of measuring the ageing of societies and their implications for public policy. The first part characterises the ongoing ageing of the population in the EU28 by relating it to past and future longer-term demographic trends for broad groups of countries. It goes beyond traditional chronological measures to include recently suggested prospective measures of ageing. The second part of the study is concerned with economic dependency ratios; a more relevant measure for summarising the economic challenges related to ageing. Three main findings emerge: first, prospective indicators of ageing reveal the challenge of population ageing to be less onerous than traditional chronological measures would suggest. Their relevance, however, will depend on the degree to which policy changes can respond to the changing age structure of the population. Second, substantial increases in the length of working lives are necessary to maintain current economic dependency ratios. Taking a year-2000 perspective view of the economic challenges of ageing shows that substantial progress has been made. Third, looking towards 2050, education will have limited direct impact on the scale of the ageing challenge.

e_LIPID: Characterisation of the Lipid Profile in the Portuguese Population

AIM: Cardiovascular disease (CVD), particularly coronary heart disease and stroke, are the leading cause of morbidity and mortality worldwide. The common forms of CVD have a complex etiology in which interactions between multiple genetic and environmental factors play an important role. Dyslipidaemia is one of many independent cardiovascular risk factors that have been identified for CVD, and its correct identification is of great importance in order to implement specific interventions, especially for CVD prevention. The aim of this study was the construction of population specific lipid percentiles and the to present the characterization of the dyslipidaemia in the Portuguese population.

Population of Peru; estimates and projections: 1962-2002,

"Prepared under a participating agency service agreement with the Office of Population, Agency for International Development."

HIV/AIDS prevention and control and population/family planning : the potential for integration of programs and activities in sub-Saharan Africa /

"Report No. 91-146-141."

Disquisitions on population : in which the principles of the essay on population by the Rev. T.R. Malthus, are examined and refuted /

Mode of access: Internet.

Sixteenth census of the United States: 1940. Population ...

At head of title: United States Dept. of Commerce... Bureau of the Census...

Trends in the use of hospital beds by older people in Australia: 1993-2002

Objective: To determine trends in use of Australian acute hospital inpatient services by older patients. Design and data sources: Secondary analysis of hospital data from the Australian Institute of Health and Welfare in the period 1993-94 to 2001-02, with population data for this period from the Australian Bureau of Statistics. Outcome measures: Population-based rates of hospital separations and bed utilisation. Results: The Australian aged population (65 years and older) increased by 18% compared with total population growth of 10%, yet the proportion of hospital beds occupied by older patients remained stable at 47%. The most substantial changes were observed in the population aged 75 years and older, with separations increasing by 89%, length of stay reducing by 35% and bed utilisation increasing by 23%. However, rates of bed utilisation (in relation to population) declined among older groups (10% decline in per capita use in population 75 years and older), but increased in the younger population (1% increase in per capita use in people younger than 65 years). Conclusion: Important trends in use of inpatient services were identified in this study. These trends are contrary to common perception. Ageing of the Australian population was not associated with an increase in the proportion of hospital beds used by older patients.

Adult-population incidence of severe sepsis in Australian and New Zealand intensive care units

Objective. To determine the population incidence and outcome of severe sepsis occurring in adult patients treated in Australian and New Zealand intensive care units (ICUs), and compare with recent retrospective estimates from the USA and UK. Design. Inception cohort study. Setting. Twenty-three closed multi-disciplinary ICUs of 21 hospitals (16 tertiary and 5 university affiliated) in Australia and New Zealand. Patients. A total of 5878 consecutive ICU admission episodes. Measurements and results. Main outcome measures were population-based incidence of severe sepsis, mortality at ICU discharge, mortality at 28 days after onset of severe sepsis, and mortality at hospital discharge. A total of 691 patients, 11.8 (95% confidence intervals 10.9-12.6) per 100 ICU admissions, were diagnosed with 752 episodes of severe sepsis. Site of infection was pulmonary in 50.3% of episodes and abdominal in 19.3% of episodes. The calculated incidence of severe sepsis in adults treated in Australian and New Zealand ICUs is 0.77 (0.76-0.79) per 1000 of population. 26.5% of patients with severe sepsis died in ICU, 32.4% died within 28 days of the diagnosis of severe sepsis and 37.5% died in hospital. Conclusion. In this prospective study, 11.8 patients per 100 ICU admissions were diagnosed with severe sepsis and the calculated annual incidence of severe sepsis in adult patients treated in Australian and New Zealand ICUs is 0.77 per 1000 of population. This figure for the population incidence falls in the lower range of recent estimates from retrospective studies in the U.S. and the U.K.

Mentoring for population health in general practice divisions

This paper describes the implementation and evaluation of a three-way model of service development mentoring. This population health mentoring program was funded by the Commonwealth Department of Health and Ageing to enable staff from eight Divisions of General Practice in South Australia to gain a sound understanding of population health concepts relevant to their workplace. The distinguishing features of service development mentoring were that the learning was grounded within an individual's work setting and experience; there was an identified population health problem or issue confronting the Division of General Practice; and there was an expectation of enhanced organisational performance. A formal evaluation found a consensus among all learners that mentoring was a positive and worthwhile experience, where they had achieved what they had set out to do. Mentors found the model of learning agreeable and effective. Division executive officers recognised enhanced skills among their "learner" colleagues, and commented positively on the benefits to their organisations through the development of well researched and relevant projects, with the potential to improve the efficiency of their population health activities.

Regional and population-scale influences on genetic diversity partitioning within costa rican populations of the pioneer tree Vochysia ferruginea mart.

The neotropical pioneer species Vochysia ferruginea is locally important for timber and is being increasingly exploited. The sustainable utilisation of this species would benefit from an understanding of the level and partitioning of genetic diversity within remnant and secondary regrowth populations. We used data from total genome (amplified fragment length polymorphism, AFLP) and chloroplast genome markers to assay diversity levels within seven Costa Rican populations. Significant chloroplast differentiation between Atlantic and Pacific watersheds was observed, suggesting divergent historical origins for these populations. Contemporary gene flow, though extensive, is geographically constrained and a clear pattern of isolation by distance was detectable when an inter-population distance representing gene flow around the central Costa Rican mountain range was used. Overall population differentiation was low (F-ST = 0.15) and within-population diversity high, though variable (H-s=0.16-0.32), which fits with the overall pattern of population genetic structure expected for a widespread, outcrossed tropical tree. However genetic diversity was significantly lower and differentiation higher for recently colonised and disturbed populations compared to that at more established sites. Such a pattern seems indicative of a pioneer species undergoing repeated cycles of colonisation and succession.