Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh Original cung cấp cho các bạn kiến thức về sinh học đề tài:Phenotypic plasticity of body pigmentation in Drosophila: Selection for litter size components: a critical review. | 483 Genet Sei Evol 1997 29 483-496 Elsevier Inra Original article Selection for litter size components a critical review M Perez-Enciso1 JP Bidanel2 1 Area de producció animal Centre UdL-IRTA 25198 Lleida Spain 2 Station de génétique quantitative et appliquée Institut national de la recherche agronomique 78352 Jouy-en-Josas cedex France Received 17 January 1997 accepted 15 July 1997 Summary The measurement of component variables such as the number of ova shed OR and its inclusion in a linear index with litter size LS or prenatal survival has been suggested in order to accelerate genetic progress for LS. Despite optimistic theoretical predictions however in no selection experiment has the advantage of including OR in an index as compared to direct selection for LS been convincingly demonstrated. A literature survey shows no clear evidence of changes in genetic parameters with selection. By contrast genetic drift may suffice to explain the less than expected usefulness of measuring OR although it is not necessarily the sole cause. It is shown that an approximate figure of how much can be gained by measuring OR relative to direct selection for LS is given by 1 ơyLK ơ2 II 1 2 with mass selection where a y is the phenotypic variance. Nonetheless the size of the experiment needed to test this prediction is likely to be very large. litter size mice number of ova shed pig index selection Resume - Selection des composantes de la taille de portée. Une synthèse critique. Plusieurs auteurs ont propose de mesurer le taux d ovulation TO et de I inclure avec la taille de la portée TP dans un indice de selection IX afin d accroitre I efficacite de la selection pour TP. Malgré des predictions théoriques optimistes aucune experience de selection n a pu démontrer de fagon convaincante I avantage d une selection sur Tindice IX par rapport à une selection directe sur TP. Une revue des experiences de selection disponibles dans la littérature montre que la réponse plus faible qu attendue
