Estimates Of Population Growth Rate Research Articles

Control and Consequences of Alternative Developmental Modes in a Poecilogonous Polychaete

SYNOPSIS. The poecilogonous polychaete Streblospio benedicti (Webster) exhibits both planktotrophic and lecithotrophic modes of larval development. The alternative trophic modes are associated with differences in age and size at maturation, offspring number, size and energetic investment, larval planktonic period, morphology and survivorship. This paper reviews a decade of research into the control and consequences of the traits associated with planktotrophy and lecithotrophy in S. benedicti . The dominant control on reproductive and developmental characters is genetic. Significant additive genetic variance has been detected for egg diameter, fecundity, larval planktonic period and aspects of larval morphology. However, environmental factors such as temperature, food quality and photoperiod, and intrinsic factors such as maternal age, exert considerable influence on non-trophic developmental traits ( e.g. , offspring number, size and energy content). Demographic consequences of development mode are reviewed for field and laboratory demes of S. benedicti dominated by individuals exhibiting either planktotrophy or lecithotrophy. Similar population size structure, fluctuations in abundance, P: B ratios, and estimated population growth rates are achieved through trade-offs between survivorship and fecundity. Development mode may best be viewed as a complex set of traits that are intimately linked developmentally and evolutionarily to other aspects of an organism's life history. Greater insight into the control and consequences of development mode should result from further investigation of these linkages

Finding Confidence Limits on Population Growth Rates: Three Real Examples Revised

EcologyVolume 75, Issue 1 p. 255-260 Article Finding Confidence Limits on Population Growth Rates: Three Real Examples Revised Elena R. Alvarez-Buylla, Elena R. Alvarez-BuyllaSearch for more papers by this authorMontgomery Slatkin, Montgomery SlatkinSearch for more papers by this author Elena R. Alvarez-Buylla, Elena R. Alvarez-BuyllaSearch for more papers by this authorMontgomery Slatkin, Montgomery SlatkinSearch for more papers by this author First published: 01 January 1994 https://doi.org/10.2307/1939401Citations: 70AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume75, Issue1January 1994Pages 255-260 RelatedInformation

Finding Confidence Limits on Population Growth Rates: Monte Carlo Test of a Simple Analytic Method

Estimates of population growth rates are subject to uncertainties because of errors incurred in estimating the individual rates of fecundity, survival and growth. However, the non-linear relationship between the population growth rate and the vital rates makes this a difficult task, and confidence limits are rarely assigned to growth rate estimates. The mean and standard error of the population growth rate may be approximated using a Taylor's series expansion. Assuming a particular type of sampling distribution for the population rate, one may use this analytic estimate to assign confidence limits. Available simulations do not enable generalizations concerning the performance of this analytic approach, especially for estimates obtained for age or stage-structured populations

Resource Variability and Life History Parameters of Leptopilina boulardi (Hymenoptera: Eucoilidae)

Influence of resource availability on the reproductive and life history parameters of the wasp parasitoid Leptopilina boulardi (Barbotin et al.) was examined. Cohorts of female wasps were exposed to patches containing an excess of appropriately aged larvae of Drosophila simulans (Sturtevant) in one of the three following schedules: (1) continuous-exposure cohort (wasps were continuously exposed to host larvae, being transferred daily to a freshly prepared vial); (2) intermittent-exposure cohort (wasps were presented with host larvae for a 24-h period every third day); (3) limited-exposure cohort (wasps were presented with host larvae daily for 1 h). Females of the continuous-exposure cohort exhibited an early peak and subsequent rapid decline in progeny production followed by a protracted period of postreproductive survival and produced a male-biased sex ratio. Females treated with intermittent and limited exposure schedules showed extended production of female progeny and produced female-biased sex ratios. The limited-exposure cohort was the most successful in terms of the highest production of female offspring, lowest sex ratio, and highest values of R0. The commonly used laboratory technique for estimating parasitoid life history parameters involving continuous exposure to excessive host larvae may lead to inaccurate estimates of reproductive potential and population growth rates.

Growth Rates of Feral Horse Populations

We studied growth rates of feral horse (Equus caballus) populations in the western United States by consolidating aerial count records for 103 management areas administered by the Bureau of Land Management (BLM). Data from most areas could not be used because of free exchange of horses between neighboring areas and/or inadequate or incomplete data. Twenty-two areas provides data that were used to assess the accuracy of aerial counts with the index-removal method. Most (24/31) aerial counts consistently detected a large proportion (85-105%) of the horses. Replicate index-removal estimates provided little evidence of progressively higher sighting probabilities that would inflate growth rate estimates, and we concluded that aerial counts could be used to obtain reliable estimates of population growth rates

Feral Horse Distribution, Habitat Use and Population Dynamics in Theodore Roosevelt National Park

Description of the ecological niche feral horses fill in Theodore Roosevelt National Park requires information on reproductive rates, home range size, individual and band affinity to home ranges, food and shelter requirements and seasonal diets. Therefore, the initial objectives will be to: 1. identify the number, size and location of home ranges for harem and bachelor stallion bands; 2. describe daily and seasonal movements of bands within identified home ranges; 3. describe the vegetation habitat types and landform types used by horses for mating, foaling, foraging, and resting cover; 4. describe seasonal horse diets; and 5. collect data on sex, age and social hierarchy within respective bands to facilitate estimation of horse population growth rates. Ultimately, this information will be used to accomplish the project goal; integrate horse requirements with those of elk, bison and the Park's vegetation communities to determine the large ungulate carrying capacity of Theodore Roosevelt National Park.

Estimates of in situ population growth rates of four tintinnine ciliate species near Kingston Harbour, Jamaica

Population growth rates of four tintinnine species were estimated in situ by incubating predator-excluded, 201 seawater samples in plastic carboys. Initial ( t=0) and final ( t=24 h) abundances were enumerated from 20 μm meshfiltered, Bouin's fixed subsamples. Assuming exponential growth, estimates of population growth rate averaged 0·80 day −1 or approximately one doubling per day. These estimates were lower than both those estimated for tintinnines from temperate regions and those predicted using a relationship that considers temperature and cell volume. Comparisons of temperate and tropical chlorophyll a concentrations suggest that food availability may limit growth rate in this tropical ecosystem.

From Hunting and Gathering to Agriculture

The purpose of this article is to provide a simple economic general equilibrium model of one of the most important prehistoric eventsthe transition from hunting and gathering to agriculture. It is hoped that such a model will help focus the discussion about this important occurrence and that it will aid in identifying the implications of the many hypotheses that have been put forth to explain why, when, and where the transition to agriculture took place. Viewed in the proper time frame, the transition to agriculture was dramatic in terms of the large number of people and the relatively short time period involved, as well as the enormous accompanying changes in the way people lived their lives. For about 4 million years man lived by harvesting wild foods. Slightly more than 10,000 years B.P. (before the present) the transition to agriculture began, and by 2,000 years B.P. the vast majority of people depended on agriculture as their main form of subsistence.' Of course, it was not only subsistence pursuits that changed. For example, estimates of population growth rates for the early agricultural period (Neolithic) are around 100 times greater than those for the hunting-gathering period.2 Estimates of population density are correspondingly higher for the agricultural period. It has been claimed that the transition in France was accompanied by a hundredfold increase in population, as opposed to a tenfold increase between the period of early farming and the present.3 The early theories of the transition, dating back to the Greeks, viewed the human economy as developing in a series of stages, with agriculture being the last stage.4 These were later modified by the introduction of environmental differences to explain why in some regions development stopped short of the last stage, or why development took place at different rates across regions. This approach fell into disfavor when the traditional sequence of stages (hunting-gathering, pastoral nomadism, agriculture) was shown to be incorrect. Rather than altering the sequence of stages, a different approach became

Time‐specific life tables for the pea aphid, Acyrthosiphon pisum (Harris), on alfalfa

SummaryTime‐specific life tables were constructed for three pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), populations using a modification ofHughes' analytical procedure. All populations were studied on second‐growth alfalfa (mid‐June to mid‐July) in south central Wisconsin; data for two populations were collected during 1980, and data for the third population were collected during 1982. The intrinsic rate of increase (rm) estimated on a physiological time (day‐degree) scale under field conditions but in the absence of natural enemies, provided a reliable estimate of potential population growth rate and was used in preference toHughes' approach of estimating potential population growth rates directly from stage structure data. Emigration by adult alatae and fungal disease were the major sources of A. pisum mortality in each of the three populations studied. These factors were most important because of their impact on reducing birth rates within the local population. Parasitism was never greater than 9 percent. Mortality attributable to predation ranged from 0.0 to about 30.0%; however, even at the highest predator densities A. pisum populations increased exponentially.

Effect of parental flowering and dispersal times on offspring fate in Daucus carota (Apiaceae).

Seeds collected from parents that flowered at different times were dispersed onto experimental plots at different times during the normal dispersal season. Parental flowering and dispersal times, which are correlated with each other, independently affected offspring germination, growth, and time of reproduction. Estimated population growth rates were highest for offspring that were dispersed early in the dispersal season and that came from early flowering parents. The data provide evidence that 1) an individual's fate is determined by the environment of the previous generation, and that 2) an individual's fitness should be calculated from life history data that span more than one generation.

Estimating population growth rates from stochastic Leslie matrices

Stochastic versions of exponential growth models predict that even when r or λ values calculated from mean vital statistics indicate exponential growth, most of the individual populations may become extinct. Several recent papers have considered this problem and some misunderstanding has arisen due to the difference between mathematical expectation of population size and most likely course of population growth. We replicated Boyce's (1977, 1979) simulations of population growth with age structure and a single randomly varying vital statistic, and reconciled some of these differences. Mean number can be projected using the dominant eigenvalue of the mean Leslie matrix, but the modal number may be considerably lower. We compared several measures of the rate of growth of the geometric mean or median of numbers and conclude that Tuljapurkar's α is an acceptable measure.

The Statistical Analysis of Population Growth Rates Calculated from Schedules of Survivorship and Fecunidity

Population growth rates can be estimated from sample cohort schedules of survivorship and fecundity, but the variation inherent in these estimates has received little attention. We define an ideal population such that it is completely described by the probabilities governing age—specific survival and reproduction. We define the lifetime contribution of an individual to population growth in a manner analogous to Fisher's (1931) reproductive values. The mean of these individual contributions is equal to the finite rate of increase for the population. We then investigate the properties of sample cohorts drawn from an ideal population. Estimates of population growth rates that are based on sample cohorts are shown to be biased. The magnitude of the bias decreases as the number of individuals used to construct the sample schedules of survivorship and fecundity is increased. This relationship conflicts with the statistical desirability of maximizing the number of estimates of the population growth rate. Bias can be reduced by pooling individual schedules to calculate a single estimate of the growth rate of the population within which individual contributions are defined. When cohort size is small, we recommend a modified jackknifing procedure for further reducing bias. To demonstrate the application of these methods, we obtain a 95% confidence interval for a rate of increased based on a sample cohort of aphids.

The phased division of the freshwater dinoflagellate Ceratium hirundinella and its use as a method of assessing growth in natural populations

SUMMARY. The nocturnal phasing and partial synchrony of cell division in Ceratium hirundinella was investigated on four occasions for dense planktonic populations in a small productive lake (Esthwaite Water). The population growth rates deduced from the proportion of cells dividing per day are compared with the rates of increase of cell density in the lake. The maximum proportion of Ceratium cells found dividing at any time was 5.8 ± 1.0%, and the time of optimum division was 03.00 hours G.M.T. The daily rate of division during the main phase of population increases was similar to that deduced from the overall population increments at that time, although during the week of collection the increase had apparently ceased temporarily. On the other three occasions, either increase of cell numbers had ceased or the population was declining, but a continued low rate of division (c. 3% day−1) was found.The nocturnal division of Ceratium in Esthwaite Water is compared with the division phasing of dinaflagellates described from elsewhere. Some general problems associated with the derivation of estimates of population growth rate from division frequency are also considered.

Use of the Leslie Matrix for Assessing Environmental Impact with an Example for a Fish Population

The Leslie matrix model for discrete population theory is examined for the assessment of the effects of environmental alterations on a species population using an eigenvalue analysis. This analysis provides estimates of population growth rate and stable age distribution. A sensitivity analysis is conducted for changes in elements of the population matrix and the resultant effect on population growth rate and stable age distribution. An example of this technique is presented for the cunner (Tautogolabrus adspersus). This example considers the effect of entrainment of cunner eggs and larvae at the intakes of power stations.

The 'White" population of South Africa in the eighteenth century.

Summary Based primarily on published genealogies and on gross figures provided by tax lists, this paper attempts to reconstruct such of the demographic characteristics of the group within South African society which defined itself as white, as may be determined. After an evaluation of the reliability of these sources, it proceeds to give estimates of the gross population growth rate, of the importance of immigration, of the sex ratio and of such aspects of nuptiality and fertility as can be ascertained in the absence of systematic information on the dates of death of individuals Finally it attempts to show the effect of the demographic structure on the social development of the colony.

Field experience in estimating population growth

This paper reports on some of the aspects of implementing the population estimation studies now being carried out-the Population Growth Estimation Study (PGE) in Pakistan, the Survey of Population Change (SPC) in Thailand, and the Demographic Survey in Turkey (TDS). The basic purpose of all these surveys is to provide reliable estimates of population growth rates for various areas within each of the countries.All the surveys under consideration are single-purpose, continuing, nation-wide studies, using fixed, area samples. The basic methodology of the studies is similar in that they aü utilize the technique of collecting data on births and deaths by two separate systems and then comparing individual events to determine whether events were recorded by both systems or only one. One list is based on periodic enumerations and the other on continuous registration.Some of the problems encountered in the various phases of the field work required to assemble the two independent lists-such as identification of enumeration units, the de facto approach vs. the de jure approach, assuring completeness of registration, and reconciliation of unmatched cases-are described and the steps taken toward their solution outlined.The author concludes that the studies are on sound methodological grounds but that their implementation, especially in developing countries, poses additional burdens.

Economic Planning in Korea

Research Article| December 01 1962 Economic Planning in Korea Charles Wolf,, Jr. Charles Wolf,, Jr. Search for other works by this author on: This Site PubMed Google Scholar Memorandum (Institute of Pacific Relations, American Council) (1933) 2 (10): 22–28. https://doi.org/10.2307/3023492 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Charles Wolf,; Economic Planning in Korea. Memorandum (Institute of Pacific Relations, American Council) 25 May 1933; 2 (10): 22–28. doi: https://doi.org/10.2307/3023492 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentAsian Survey Search This content is only available via PDF. Article PDF first page preview Close Modal You do not currently have access to this content.