Dynamic and static selection policies when generations overlap

1979 ◽  
Vol 28 (2) ◽  
pp. 149-155
Author(s):  
I. R. Hopkins
Keyword(s):  
Age Groups ◽  
Genetic Differences ◽  
Discount Rates ◽  
Dynamic Selection ◽  
Selection Policy ◽  
Large Numbers ◽  
Dynamic Policy ◽  
Selection Policies ◽  
Genetic Responses ◽  
Genetic Contributions

ABSTRACTWhere genetic differences between age groups change during a selection programme, proportional contributions of each age group to replacements should also change in order to maximize genetic responses to selection. Sums of discounted returns were estimated for such a ‘dynamic’ selection policy and these were compared with those from ‘static’ selection policies in which genetic contributions of different age groups remained unchanged. Four selection methods, two sets of genetic differences between age groups at the outset, three age structures and two discount rates were used.The results showed that the superiority of the dynamic policy was greatest where genetic differences at the outset differed most markedly from their steady-state values, where discount rates are high and where there are large numbers of age groups and the selection method allows culling in all age groups. Under most conditions initial genetic differences are probably the most important factor. The proportional advantage in sums of discounted returns is variable and generally small within the framework of this study ranging from zero to roughly 8% unless breeding objectives before and during the programme were negatively correlated. In the latter case the proportional superiority of the dynamic policy was much greater.

Genetic responses in the early years of selection programmes using genetic differences between generations

1979 ◽  
Vol 28 (1) ◽  
pp. 65-77 ◽  
Author(s):  
I. R. Hopkins ◽  
J. W. James
Keyword(s):  
Age Groups ◽  
Genetic Differences ◽  
Early Years ◽  
Economic Returns ◽  
Investment Appraisal ◽  
Multi Stage ◽  
Parent Selection ◽  
Group A ◽  
Definition Of ◽  
Genetic Responses

ABSTRACTRecurrence relationships are used to relate breeding values of age-sex classes from different time periods. Their application to single-stage (progeny) and multi-stage (parent) selection is demonstrated. These relationships enable definition of the effect of age structure, initial genetic differences between age groups, and the extent to which allowances are made for these or later genetic differences between age groups. The expressions derived show that, given initial genetic differences between age groups, subsequent progeny means will fluctuate even under completely random selection. Using these means as a basis for measuring responses to selection, it is shown that there can be selective effects where selection is at random within parental age classes. A careful definition of the alternative programme is therefore important in interpreting results of selection experiments and in investment appraisal of selection programmes.These models were then used to describe economic returns from parent and progeny selection programmes and from programmes in which returns are realized in more than one age group. A further extension of the model accommodates the effects of finite population size on returns through its effects on genetic variance.By separating the (constant) within- and (fluctuating) between-group components of the selection differential within the recurrence relationships a number of computational problems are overcome.

scholarly journals Contributions to the biology of the mackerel, Scomber scombrus L. III. Age and growth

1952 ◽  
Vol 30 (3) ◽  
pp. 549-569 ◽  
Author(s):  
G. A. Steven
Keyword(s):  
Sexual Maturity ◽  
Age Groups ◽  
Age And Growth ◽  
Small Fish ◽  
Massachusetts Bay ◽  
Scomber Scombrus ◽  
Bay Area ◽  
Large Numbers ◽  
The Common ◽  
Young Of The Year

The first serious attempt to determine the age and growth rate of the common mackerel (Scomber scombrus L.) appears to have been made by Captain Atwood in 1856 (quoted by Brown Goode, 1884, p. 116) in the Massachusetts Bay area of northern North America. Small fish caught by Atwood in October of that year measuring 6½–7 in. in length (16.5–17.5 cm.) he believed to be the young of the year (i.e. they belonged to the O-group). Mackerel belonging to this group he calls ‘spikes’. ‘Blinks', ‘tinkers’ and ‘second size’ fish he assigns to the I-, II- and III-year age groups respectively, but unfortunately gives no data as to the sizes of those categories, merely stating that everyone well acquainted with mackerel makes the same groupings ‘as there seems to be a line of demarkation between the different kinds which stands out prominently’. Sixteen years later, on 27 July 1872, Malm (1877, p. 409) observed large numbers of small mackerel close inshore in the Gullmarfjord near Christineberg. Several tons of those mackerel were enclosed in a seine, but only ten specimens were retained as all the others escaped through the meshes. These ten fish ranged in length from 67 to 100 mm. and Malm surmised their age to be 13 months. Collett (1880, p. 18) stated that on the coast of Norway I-year-old mackerel are ‘fingerlang’. To fish of 20 cm., taken at the end of August, he ascribed (without supporting data) an age of 2 years, with sexual maturity supervening at 3 years at an unspecified length.

Article

2002 ◽  
Vol 19 (2) ◽  
pp. 106-122 ◽  
Author(s):  
Einar Ødegård ◽  
Anne Line Bretteville-Jensen ◽  
Astrid Skretting
Keyword(s):  
Drug Abuse ◽  
Cohort Analysis ◽  
Age Groups ◽  
Data Sets ◽  
Age Group ◽  
Heroin Abuse ◽  
Large Numbers ◽  
Heroin Abusers ◽  
Questionnaire Surveys ◽  
Questionnaire Studies

Einar Ødegård & Anne Line Bretteville-Jensen & Astrid Skretting: The development of drug abuse in Norway in the 1990s This article aims to shed light on the development of drug abuse in Norway during the 1990s. The data come from various different sources, including questionnaire studies as well as other data sets describing the extent of drug abuse in the country. There has been a marked increase in drug abuse during the 1990s. Data from annual youth surveys in 1990 to 1995 indicate that between 8 and 10 per cent of youths aged 15–20 had ever used cannabis, whereas the figure during the latter half of the decade was substantially higher at 18–19 per cent. Surveys in the whole population also point at an increase from 1991 through to 1999: in 1991 the proportion indicating they had ever used cannabis was 8.2%, by 1999 the figure had risen to 12.5%. Furthermore, a simple cohort analysis clearly indicates that large numbers are continuing to use cannabis: the figures are also rising in older age groups. With the growing prevalence of cannabis use in younger age groups we may therefore expect to see increasing numbers of regular and frequent cannabis users in the whole population as well. Drug seizures by the police and customs have increased sharply during the latter half of the 1990s: this applies not only to amphetamine and ecstasy but also cocaine and LSD. This is supported by the results of annual questionnaire surveys among youths, who are reporting a marked increase in the use of these types of drugs. In the early 1990s around 1% of youths in the age group 15–20 said they had ever used amphetamine. This figure remained more or less unchanged through to the mid-1990s. However by the end of the decade around 4% said they had used amphetamine. The data from youth surveys furthermore indicate that there is considerable overlap in the use of amphetamine and ecstasy. In this material the sharpest increase is recorded in the proportion of those indicating they have used both amphetamine and ecstasy. There are several indicators which describe the extent of heroin abuse. All these indicators show that there has been a sharp increase in heroin abuse during the 1990s. A simple mortality analysis suggests that the number of heroin abusers has doubled over the past decade. Drug abuse has also spread markedly both in relation to age groups and geographically: today the problem is by no means limited to any specific age group, nor just to a few major cities.

scholarly journals Genetic contributions to agricultural sustainability

2007 ◽  
Vol 363 (1491) ◽  
pp. 591-609 ◽  
Author(s):  
Elizabeth S Dennis ◽  
Jeffrey Ellis ◽  
Allan Green ◽  
Danny Llewellyn ◽  
Matthew Morell ◽  
...  
Keyword(s):  
New Technologies ◽  
Crop Improvement ◽  
Breeding Population ◽  
Plant Genome ◽  
Yield Potential ◽  
Large Numbers ◽  
Phases Of Development ◽  
New Varieties ◽  
And Function ◽  
Genetic Contributions

The current tools of enquiry into the structure and operation of the plant genome have provided us with an understanding of plant development and function far beyond the state of knowledge that we had previously. We know about key genetic controls repressing or stimulating the cascades of gene expression that move a plant through stages in its life cycle, facilitating the morphogenesis of vegetative and reproductive tissues and organs. The new technologies are enabling the identification of key gene activity responses to the range of biotic and abiotic challenges experienced by plants. In the past, plant breeders produced new varieties with changes in the phases of development, modifications of plant architecture and improved levels of tolerance and resistance to environmental and biotic challenges by identifying the required phenotypes in a few plants among the large numbers of plants in a breeding population. Now our increased knowledge and powerful gene sequence-based diagnostics provide plant breeders with more precise selection objectives and assays to operate in rationally planned crop improvement programmes. We can expect yield potential to increase and harvested product quality portfolios to better fit an increasing diversity of market requirements. The new genetics will connect agriculture to sectors beyond the food, feed and fibre industries; agri-business will contribute to public health and will provide high-value products to the pharmaceutical industry as well as to industries previously based on petroleum feedstocks and chemical modification processes.

Sound change and social structure in a rural community

1983 ◽  
Vol 12 (3) ◽  
pp. 313-328 ◽  
Author(s):  
Timothy C. Frazer
Keyword(s):  
Social Structure ◽  
American English ◽  
Age Groups ◽  
The United States ◽  
Sound Change ◽  
Rural Life ◽  
Large Numbers ◽  
Past Half Century ◽  
The Social ◽  
Past Half

ABSTRACTMost studies of sound change in the United States have focused on the social strata of urban societies. In the American cornbelt, however, the most important social distinctions are horizontal rather than vertical. A fundamental ethnic division dating back to original settlement of the area opposes town and countryside dwellers. A study of fifty-one speakers in a rural area of Illinois shows fronting and raising of (aw) to be considerably more advanced among countryside dwellers than among town residents. Furthermore, the countryside population underwent a profound social and economic change during the past half century as large numbers of subsistence farmers abandoned the land and rural life altogether, leaving behind a smaller number of farmers whose larger operations meant that the economic and social status of the average farmer considerably improved. An examination of town and countryside age groups from the data base shows that an increase in the fronting and raising of (aw) took place primarily in a single generation most affected by the change in the farm population. At least temporarily, fronted and raised (aw), despite an overt nonstandard status documented in more than a century of speech and language textbooks, suddenly acquired a new prestige – spreading even to town populations – along with a reassertion of rural values and rural life. (Sound change, social structure, rural society, American English, sociolinguistics, dialectology)

Some optimum age structures and selection methods in open nucleus breeding schemes with overlapping generations

1978 ◽  
Vol 26 (3) ◽  
pp. 267-276 ◽  
Author(s):  
I. R. Hopkins
Keyword(s):  
Survival Rates ◽  
Age Groups ◽  
Selection Methods ◽  
Selection Procedures ◽  
Transfer Rates ◽  
Breeding Schemes ◽  
Nucleus Breeding ◽  
Genetic Responses ◽  
Open Nucleus ◽  
Age Structures

ABSTRACTDesigns of open nucleus breeding schemes, which comprise a nucleus having the best males and females and a base comprising the remainder, with some base-born individuals used in the nucleus and vice versa, are studied.Steady-state genetic responses, optimum transfer rates between nucleus and base in both sexes, and genetic differences between nucleus and base are estimated for a range of age structures, selection either within or among age groups (selection methods), nucleus sizes, mating ratios, fertility rates and survival rates appropriate to sheep and cattle populations. With optimum transfer rates between layers maximum or near maximum genetic responses are obtained with nucleus sizes varying from 2 to 15% of the population. Optimum transfer rates are fairly stable for nucleus sizes larger than about 5% and where the same selection procedures are used in both layers. However, a small nucleus with more efficient age structures and selection procedures and more accurate selection than in the base is economically desirable, and then almost no base-born females should be selected as nucleus replacements and up to 70% of male replacements for the base should come from the base. Optimum age structures differed markedly between selection methods.Although few ‘rules of thumb’ about optimum age structures and transfer rates are sufficiently robust to be widely recommended in commercial situations, the nucleus breeding system behaves according to a few basic principles that can be used to predict the direction if not the magnitude of effects of changes in structure.

STUDIES OF WATERFOWL IN BRITISH COLUMBIA: GREATER SCAUP DUCK, LESSER SCAUP DUCK

1941 ◽  
Vol 19d (4) ◽  
pp. 113-138 ◽  
Author(s):  
J. A. Munro
Keyword(s):  
British Columbia ◽  
Sex Ratio ◽  
Salt Water ◽  
Age Groups ◽  
Economic Significance ◽  
Lesser Scaup ◽  
Large Numbers ◽  
Salmon Eggs ◽  
Winter Flocks ◽  
Coast Region

Nyroca marila is an abundant migrant through British Columbia and large numbers winter in the coast region. The sex ratio in winter flocks is predominantly male. Chara was the chief food eaten by 57 specimens from Okanagan Lake, miscellaneous vegetable matter was second, and molluscs third in importance. Food items, listed in order of importance, on coast streams and lakes were: vegetable matter, molluscs, salmon eggs, salmon flesh, and, on salt water: gastropods, sea lettuce (Ulva sp.), crustaceans, and herring eggs. N. affinis nests commonly in parts of the dry interior and elsewhere in the province is a migrant and scarce winter visitant. Sex ratio is predominantly male. Courtship continues through April and May; laying commences in June and late clutches are found in August. Females defend their young vigorously and a habit of combining broods has a probable survival value. Males raft on certain lakes in July and go into eclipse as flight feathers are shed. These populations include yearling and post-breeding females and later, adolescents. The former moult at this time. Adults migrate early and those remaining are largely young of the year. Amphipods are the chief food of all age groups on the nesting ground; aquatic insects and seeds of aquatic plants are also important. Both species of scaup ducks are economically important as food and for sport in the interior but less so on the coast where, because of a different diet, their flesh is less palatable. It was not determined whether the consumption of salmon eggs and herring eggs is of economic significance. Elsewhere than on the coast scaup ducks are related to other interests only to the limited extent to which they are food competitors of trout and other commercially valuable fishes.

scholarly journals Age Structure and Living Arrangements Shape the Vulnerability of Spanish Provinces to Outbreaks of Covid-19

2020 ◽  
Author(s):  
Diederik Boertien ◽  
Albert Esteve ◽  
Iñaki Permanyer
Keyword(s):  
Age Structure ◽  
Living Arrangements ◽  
Age Groups ◽  
Household Transmission ◽  
Private Households ◽  
Large Numbers ◽  
Risk Of Mortality ◽  
Household Members ◽  
Combine Information

BackgroundPrevious research has documented how age structures and co-residence patterns shape the vulnerability of populations to outbreaks of covid-19, with Spain being among the most vulnerable countries.ObjectiveTo document the role of age-specific co-residence patterns in shaping the vulnerability of Spanish provinces to mortality arising from within-household transmission of covid-19.MethodWe use data from the Spanish Population Registry 2018 on 10% of the population residing in private households in Spain. We combine information on the age and number of household members with infection fatality ratios related to covid-19 to estimate the average number of deaths per infection if a person becomes infected and transmits the virus to other household members. ResultsChildren live in the largest households of all age groups on average. However, the age profile of the persons that children live with reduces, but does not eliminate, the risk of mortality arising due to within-household transmission of the virus.Provinces with aged populations face a double challenge. Not only do they have large numbers of vulnerable persons due to their age, older persons are also more likely to share the same households in aged provinces. Contribution We show how the vulnerability of Spanish provinces to covid-19 varies due to age structure and co-residence patterns and document the role of specific age-based co-residence arrangements in this result.

scholarly journals Competition alters species’ plastic and genetic response to environmental change

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lynn Govaert ◽  
Luis J. Gilarranz ◽  
Florian Altermatt
Keyword(s):  
Environmental Change ◽  
Aquatic Organisms ◽  
Dispersal Ability ◽  
Phenotypic Change ◽  
Competing Species ◽  
Species Persistence ◽  
Species Survival ◽  
Genetic Responses ◽  
Genetic Contributions ◽  
Response To Environmental Change

AbstractSpecies react to environmental change via plastic and evolutionary responses. While both of them determine species’ survival, most studies quantify these responses individually. As species occur in communities, competing species may further influence their respective response to environmental change. Yet, how environmental change and competing species combined shape plastic and genetic responses to environmental change remains unclear. Quantifying how competition alters plastic and genetic responses of species to environmental change requires a trait-based, community and evolutionary ecological approach. We exposed unicellular aquatic organisms to long-term selection of increasing salinity—representing a common and relevant environmental change. We assessed plastic and genetic contributions to phenotypic change in biomass, cell shape, and dispersal ability along increasing levels of salinity in the presence and absence of competition. Trait changes in response to salinity were mainly due to mean trait evolution, and differed whether species evolved in the presence or absence of competition. Our results show that species’ evolutionary and plastic responses to environmental change depended both on competition and the magnitude of environmental change, ultimately determining species persistence. Our results suggest that understanding plastic and genetic responses to environmental change within a community will improve predictions of species’ persistence to environmental change.

scholarly journals The monetary value of human life losses associated with COVID-19 in Turkey

2020 ◽  
Vol 2 ◽  
pp. 44
Author(s):  
Joses Muthuri Kirigia ◽  
Rose Nabi Deborah Karimi Muthuri ◽  
Lenity Honesty Kainyu Nkanata
Keyword(s):  
Life Expectancy ◽  
Human Life ◽  
Age Groups ◽  
International Health ◽  
Years Of Life Lost ◽  
Age Group ◽  
Health Coverage ◽  
Discount Rates ◽  
Monetary Value ◽  
National Life

Background:  This study aimed to appraise the monetary value of human life losses associated with COVID-19 in Turkey. To our knowledge, it is the first study in Turkey to value human life losses associated with COVID-19.  Methods: A human capital approach (HCA) model was applied to estimate the total monetary value of the 4,807 human lives lost in Turkey (TMVHL) from COVID-19 by 15 June 2020. The TMVHL equals the sum of monetary values of human lives lost (MVHL) across nine age groups. The MVHL accruing to each age group is the sum of the product of discount factor, years of life lost, net GDP per capita, and the number of COVID-19 deaths in an age group. The HCA model was re-calculated five times assuming discount rates of 3%, 5%, and 10% with a national life expectancy of 78.45 years; and the world highest life expectancy of 87.1 years and global life expectancy of 72 years with 3% discount rate. Results: The 4807 human life losses from COVID-19 had a TMVHL of Int$1,098,469,122; and a mean of Int$228,514 per human life. Reanalysis with 5% and 10% discount rates, holding national life expectancy constant, reduced the TMVHL by Int$167,248,319 (15.2%) and Int$ 429,887,379 (39%), respectively. Application of the global life expectancy reduced the TMVHL by 36.4%, and use of world highest life expectancy increased TMVHL by 69%. However, the HCA captures only the economic production losses incurred as a result of years of life lost. It ignores non-market contributions to social welfare and the adverse effects of economic activities. Conclusions: Additional investment is needed to bridge the persisting gaps in International Health Regulations capacities, Universal Health Coverage, and safely managed water and sanitation services.

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