Size of population required for artificial selection

SUMMARYIt is widely acknowledged that genetic drift is an important source of variation in response to artificial directional selection. How large should a selection line be in order to reduce the effect of genetic drift to an acceptably low level?This paper investigates two criteria that can be used to answer this question in relation to short-term response to selection. The first criterion is coefficient of variation of response, and the second criterion is chance of success, where a successful selection programme is one in which the observed response is greater than a certain proportion, β, of expected response.For a simple mass selection programme with intensity i and heritability h2, the size of population required in order for the coefficient of variation of response to be γ after t generations, is approximately 2/(γih)2t, and the size required for the chance of success to be α after t generations is approximately 2{zα/(β−l)ih}2/t, where zα is the standard normal deviate corresponding to the probability α.As an example, suppose it is required that after t generations the coefficient of variation of response be 10% or that there be a 90% chance of achieving at least 9/10 of expected response. Since ih ≤ 2 in most selection programmes, the size of population required is at least 50/t or 82/t respectively. If ih ≤ 1, the corresponding sizes are 200/t and 328/t.Results are extended to enable the calculation of size of population required for any type of artificial directional selection programme, including those in which generations overlap.

Download Full-text

Estimating Long Term Extreme Slamming From Breaking Waves

Volume 3: Structures, Safety and Reliability ◽

10.1115/omae2015-41505 ◽

2015 ◽

Author(s):

Gunnar Lian ◽

Sverre K. Haver

Keyword(s):

Coefficient Of Variation ◽

Limit State ◽

Breaking Waves ◽

Contour Method ◽

Short Term ◽

Sea State ◽

Response Process ◽

Term Response ◽

Short Term Variability

Characteristic loads for design are defined in terms of their annual exceedance probability, q. For ultimate limit state (ULS) q = 10−2, while q = 10−4 for accidental limit state (ALS). In principle a full long term analysis is required in order to obtain consistent estimates. This is straight forward for linear response problems, while it is a challenge for non-linear problems in particular if they additionally are of an on-off nature. The latter will typically be the case for loads due to breaking wave impacts. The Contour line approach is an alternative convenient method to estimate the long term extreme response, based on short term statistics from an appropriate sea state. The consequence of very large short term variability (large coefficient of variation for 3-hour extreme value) on the application of the contour method will be discussed. The long term integral is carried out over all sea state combinations. The lowest sea states will of course not affect the extremes. However, for the impact problem the short term variability is much larger than for most response cases. The coefficient of variation of the 3-hour maximum impact pressure is often between 0.5 and 1, while for a typical response process it is between 0.1 and 0.2. Due to the large variability, lower sea states than normal will contribute to the long term response. In this paper the irregularity of the response surface, and the uncertainties related to the number of seeds used in each sea state is looked into. The focus is on slamming loads from breaking waves, and some results from a model test are presented. The uncertainties in long term response from slamming loads are compared to a more common response process. The effect on the long term response when integrating over a reduced area of sea states in the scatter diagram is discussed.

Download Full-text

A simple method for increasing the response to artificial selection

Genetics Research ◽

10.1017/s0016672300026574 ◽

1984 ◽

Vol 44 (3) ◽

pp. 347-349 ◽

Cited By ~ 15

Author(s):

Miguel Angel Toro ◽

Blanca Maria Nieto

Keyword(s):

Genetic Drift ◽

Artificial Selection ◽

Gene Pool ◽

Selection Intensity ◽

Next Generation ◽

Short Term ◽

Simple Method ◽

Large Gene ◽

Term Response

SUMMARYSelection theory usually assumes an equally probable contribution of each selected individual to a large ‘gene pool’ from which the individuals to be measured in the next generation are sampled. With unequal contributions it is possible to find several sets of values for N (the number of selected individuals) and fi (probability of contribution of the ith individual) such that the same selection intensity is attained. It is suggested that the set of values producing minimum genetic drift should be chosen in order to increase the long-term response without any reduction in the short-term advance.

Download Full-text

629 Clinical and echocardiographic predictors of short term response to cardiac resynchronization therapy

EP Europace ◽

10.1016/s1099-5129(05)80426-x ◽

2005 ◽

Vol 7 ◽

pp. 144-144

Keyword(s):

Cardiac Resynchronization Therapy ◽

Cardiac Resynchronization ◽

Resynchronization Therapy ◽

Short Term ◽

Term Response

Download Full-text

Artificial liver support in acute liver injury and graft dysfunction: MARS increases short-term response to therapy and predicts further course of disease

10.1055/s-0037-1605114 ◽

2017 ◽

Author(s):

U Gerth ◽

G Thölking ◽

A Hüsing-Kabar ◽

I Kabar ◽

H Schmidt ◽

...

Keyword(s):

Liver Injury ◽

Acute Liver Injury ◽

Response To Therapy ◽

Artificial Liver ◽

Graft Dysfunction ◽

Short Term ◽

Liver Support ◽

Artificial Liver Support ◽

Course Of Disease ◽

Term Response

Download Full-text

Short term response of plankton community to nutrient enrichment in central eastern Arabian Sea: Elucidation through mesocosm experiments

Journal of Environmental Management ◽

10.1016/j.jenvman.2021.112390 ◽

2021 ◽

Vol 288 ◽

pp. 112390

Author(s):

A.C. Anil ◽

D.V. Desai ◽

L. Khandeparker ◽

V. Krishnamurthy ◽

K. Mapari ◽

...

Keyword(s):

Nutrient Enrichment ◽

Arabian Sea ◽

Plankton Community ◽

Short Term ◽

Eastern Arabian Sea ◽

Mesocosm Experiments ◽

Central Eastern ◽

Term Response

Download Full-text

Unfolding the case of returnees: How the European Union and its member States are addressing the return of foreign fighters and their families

International Review of the Red Cross ◽

10.1017/s1816383121000217 ◽

2021 ◽

pp. 1-23

Author(s):

Carlota Rigotti ◽

Júlia Zomignani Barboza

Keyword(s):

European Union ◽

Perceived Threat ◽

The European Union ◽

Security Threat ◽

Short Term ◽

Member States ◽

Foreign Fighters ◽

Term Response

Abstract The return of foreign fighters and their families to the European Union has mostly been considered a security threat by member States, which consequently adopt repressive measures aimed at providing an immediate, short-term response to this perceived threat. In addition to this strong-arm approach, reintegration strategies have also been used to prevent returnees from falling back into terrorism and to break down barriers of hostility between citizens in the long term. Amidst these different strategies, this paper seeks to identify which methods are most desirable for handling returnees.

Download Full-text