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PubMed2004

Demography, life history, and social structure in Propithecus diadema edwardsi from 1986-2000 in Ranomafana National Park, Madagascar.

Prosimian lemurs differ fundamentally from anthropoid primates in many traits related to social structure. By exploring the demography of Milne-Edwards' sifakas (Propithecus diadema edwardsi), and comparing it to other well-studied primates, we explore the effect of demographic and life-history factors on social structure. Specifically, we compare lemur survivorship and fertility patterns to two published composite models: one created for New World and another created for Old World monkeys. Using longitudinal data collected on individual Propithecus diadema edwardsi from four study groups from 1986-2000 in Ranomafana National Park, Madagascar, we quantify 1) group composition, 2) birth seasonality, 3) interbirth interval, 4) life-table values, and 5) population growth estimates. The mortality, survivorship, and life-expectancy schedules indicate high infant and juvenile mortality. Fertility remains high until death. The intrinsic rate of increase and net reproductive rate indicate a shrinking population. We suggest that high mortality rather than low fertility causes the observed population decline. While sifaka survivorship closely resembles New World patterns, fertility resembles Old World patterns, i.e., like New World monkeys, few sifakas survive to reproductive age, and those that do, reproduce at a slow rate resembling the Old World pattern. This necessarily impacts social structure. An adult sifaka at the end of her lifespan will have one only daughter who survives to reproductive age, compared to 3.4 for New World or 2.7 for Old World monkeys. Demography limits the formation of large kin-based groups for sifakas, and survivorship and fertility patterns do not easily permit sifakas to form large same-sex family groups.

Animals↗
PubMed1997

A demographic approach to selection.

The concepts of demography provide a means of combining the ecological approach to population growth with the genetical approach to natural selection. We have utilized the demographic theory of natural selection developed by Norton and Charlesworth to analyze life history schedules of births and deaths for populations of genotypes in Drosophila pseudoobscura. Our populations illustrate a stable genetic equilibrium, an unstable genetic equilibrium, and a case of no equilibrium. We have estimated population growth rates and Darwinian fitnesses of the genotypes and have explored the role of population growth in determining natural selection. The age-specific rates of births and deaths provide insights into components of selection. Both viability and fertility are important components in our populations.

Animals↗
PubMed1991

Temperature-dependent reproduction and survival of Gyrodactylus salaris Malmberg, 1957 (Platyhelminthes: Monogenea) on Atlantic salmon (Salmo salar L.).

The relationship of survival and reproduction of Gyrodactylus salaris Malmberg on the Atlantic salmon (Salmo salar) to water temperature (2.5-19.0 degrees C), was studied on the basis of temporal sequence of births and age at death of individual parasites on isolated salmon, and of infrapopulation growth on isolated and grouped salmon. Mean life-span of the parasite was negatively correlated with water temperature: 33.7 days at 2.5 degrees C and 4.5 days at 19.0 degrees C. The average number of offspring per parasite peaked between 6.5 and 13.0 degrees C, and was approximately 2.4 at these two temperatures. Both the period between the successive births of the offspring (max 4) and the estimated generation time were negatively correlated with temperature. The innate capacity for increase (rm) was positively correlated with temperature: from 0.02 (/parasite/day) at 2.5 degrees C to 0.22 (/parasite/day) at 19.0 degrees C. Growth of the infrapopulations was positively correlated with water temperature and was higher on isolated fish than on grouped fish, though less than the potential parasite population growth estimated from rm. In the infrapopulations the mean intensity of parasites continued to increase throughout all the experiments on both isolated fish and on grouped fish.

Analysis of Variance↗
PubMed2003

[Application of the Unmet Obstetrical Needs method in the III neighborhood of Niamey, Niger (1999)].

West Africa has probably the highest levels of maternal mortality in the world. A new method has been developed by the Institute of Tropical Medicine of Antwerp (Belgium) that gives an estimate of the Uncovered Obstetrical Need. This technique tested in different Western African countries has been now evaluated also in an urban medical district in Niamey, capital of Niger, for the year 1999. The uncovered obstetrical need has been estimated at 15 major Obstetrical Interventions for this period; this means that 15 pregnant women didn't undergo a major surgical intervention necessary to save their life and that they probably died because of this non-intervention. We met quite a lot of problems with this new method: (i) the first problem is related to the difficulty to obtain correct demographic information: it is very difficult to estimate population growth in urban african areas, present population and number of attended births. (ii) The second difficulty came from sociocultural habits: primipare women in Niger go back to their family to deliver (and the place where their family lives is not necessarily the same as the place where they stay with their husband); it is quite possible that a number of primipare women needing a major surgical intervention didn't undergo this intervention because they delivered in their home village (and perhaps died there). (iii) At last, the estimation of a reference rate (calculated at 0.9% for Niger) implies that all women needing a major obstetrical intervention in Niamey, and having a theoretical easy access to medical infrastructures (first line as second line hospitals) present themselves when having a major obstetrical problem. This is probably "wishful thinking". The interest of this new method lies in the fact that it is a cheap technique and easy to put into practice ... provided that one disposes of medical infrastructures that collect correctly all necessary medical information.

Birth Rate↗
PubMed2006

Land-use forecasting and hydrologic model integration for improved land-use decision support.

This paper develops a methodology for integrating a land-use forecasting model with an event scale, rainfall-runoff model in support of improving land-use policy formulation at the watershed scale. The models selected for integration are loosely coupled, structured upon a common GIS platform that facilitates data exchange. The hydrologic model HEC-HMS is calibrated for a specific storm event that occurred within central Washington State. The land-use forecasting model, What If? is implemented to forecast future spatial distributions of low-density residential land-uses under low and high population growth estimates. Forecasted land-use distribution patterns for the years 2015, 2025, and 2050 are then used as land-use data input for the calibrated hydrologic model, keeping all other parameters constant. Impacts to the stream discharge hydrograph are predicted as the study area becomes increasingly developed as forecasted by What If?. The initial results of this integration process demonstrate the synergy that can be generated through the linkage of the selected models. The ability to quantifiably forecast the potential hydrologic implications of proposed land-use policies before their implementation offers land-use decision-makers a valuable tool for discerning which proposed land-use alternatives will be effective at minimizing storm water runoff.

Conservation of Natural Resources↗
PubMed2006

Trend in incidence of hepatitis B virus infection during a decade of universal childhood hepatitis B vaccination in Saudi Arabia.

Since 1990, the national strategy to eliminate hepatitis B virus (HBV) infection in Saudi Arabia has included universal administration of HBV vaccine to all infants. From 1990 to 1995 this vaccine was also routinely administered to children at school entry. The prevalence of hepatitis B surface antigen (HBsAg) among children before this programme was reported to be 6.7%. The objective of this study was to describe the trend in incidence of HBV infection over a decade of surveillance following the introduction of this programme. From January 1990 to December 1999 a total of 30,784 cases of HBV infection (positive for HBsAg) were reported. The total number of HBV infections among children <15 years of age was 4180 cases, with a prevalence of 0.05%. The total number of HBV infections among adults was 26,604 cases, with a prevalence of 0.22%. The prevalence varied by region, ranging from 0.03% to 0.72% with a mean prevalence of 0.15%. There was a clear decline in incidence among children whereas the incidence in adults slightly rose, perhaps owing to population growth estimated to be 3.3% annually. This study showed that the universal childhood HBV vaccination programme had an enormous positive impact on HBsAg seroprevalence among children in Saudi Arabia.

Adolescent↗
PubMed2000

Aeration management for stored hard red winter wheat: simulated impact on rusty grain beetle (Coleoptera: Cucujidae) populations.

Simulation studies were conducted to determine temperature accumulations below defined thresholds and to show the impact of controlled aeration on populations of the rusty grain beetle, Cryptolestes ferrigineus (Stephens), a major secondary pest of stored wheat, Triticum aestivum (L.). Recorded data from weather stations in Texas, Oklahoma, Kansas, eastern New Mexico, and eastern Colorado (356 total) were used to determine hours of temperature accumulation below 23.9 degrees C in June and July, 15.6 degrees C in September and October, and 7.2 degrees C in December. At an airflow rate of 0.0013 m3/s/m3 (0.1 cubic ft3/min/bu), which requires 120 h of temperatures below the specified threshold to complete an aeration cycle, summer cooling at 23.9 degrees C in bulk-stored wheat could be completed throughout the hard red winter wheat zone except for extreme southern Texas. An early-autumn cooling cycle at 15.6 degrees C could not be completed throughout most of Texas and Oklahoma before the end of September. The late-autumn cooling cycle could be completed in all states except Texas by the end of November. Five geographic regions were delineated and the times required for completion of the summer, early-autumn, and late-autumn cooling cycles within each region were estimated. Population growth of the rusty grain beetle was modeled for San Antonio, TX; Abilene, TX; Tulsa, OK; Topeka KS; and Goodland, KS, by predicting the numbers of adults in the top, outer middle, outer periphery, and the center of the bin during a 1-yr storage season. Populations of C. ferrugineus in San Antonio and Austin were predicted to exceed the Federal Grain Inspection Service (FGIS) threshold of two beetles per kilogram of wheat in all four levels of the bin during late autumn, decline during the winter, and increase the following spring. In Midland, TX, and Oklahoma City, OK, populations were predicted to exceed the threshold only in the top and outer middle of the bin, whereas populations in the Kansas locations were not predicted to exceed the threshold at any time.

Air↗
PubMed2001

Variation in cadmium uptake, feeding rate, and life-history effects in the gastropod potamopyrgus antipodarum: linking toxicant effects on individuals to the population level.

A life-table response experiment was performed to investigate the effects of sediment-bound cadmium on individual life-history traits and feeding rates of four clones of Potamopyrgus antipodarum. Demographic effects were evaluated using a simple two-stage model to estimate population growth rate (lambda). Decomposition analysis was performed to investigate the contributions of each of the affected life-history traits to the effects observed on lambda, and elasticity analysis was applied to examine the relative sensitivity of lambda to changes in each of the life-history traits. Interclonal differences in tolerance to sediment-bound cadmium were statistically significant but were within an order of magnitude. There were no consistent patterns among clones in terms of which individual life-history trait was most or least sensitive to cadmium exposure. The relative performance of clones did not rank consistently across the cadmium gradient and was dependent on which trait was measured. Although lambda was most sensitive to changes in survival terms, the effects of cadmium on time to first reproduction and reproductive output were the major causes of reductions in lambda. Large percent reductions in some of the individual life-history traits were attenuated at the population level, but very small effects on population growth rate were statistically significant.

Animals↗
PubMed1981

[Surveys].

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Abortion, Induced↗