title: Heritable environmental variance causes nonlinear relationships between traits: application to birth weight and stillbirth of pigs.
abstract: There is recent evidence from laboratory experiments and analysis of livestock populations that not only the phenotype itself, but also its environmental variance, is under genetic control. Little is known about the relationships between the environmental variance of one trait and mean levels of other traits, however. A genetic covariance between these is expected to lead to nonlinearity between them, for example between birth weight and survival of piglets, where animals of extreme weights have lower survival. The objectives were to derive this nonlinear relationship analytically using multiple regression and apply it to data on piglet birth weight and survival. This study provides a framework to study such nonlinear relationships caused by genetic covariance of environmental variance of one trait and the mean of the other. It is shown that positions of phenotypic and genetic optima may differ and that genetic relationships are likely to be more curvilinear than phenotypic relationships, dependent mainly on the environmental correlation between these traits. Genetic correlations may change if the population means change relative to the optimal phenotypes. Data of piglet birth weight and survival show that the presence of nonlinearity can be partly explained by the genetic covariance between environmental variance of birth weight and survival. The framework developed can be used to assess effects of artificial and natural selection on means and variances of traits and the statistical method presented can be used to estimate trade-offs between environmental variance of one trait and mean levels of others.
authors: Animal Breeding and Genomics Centre, Wageningen University, 6700 AH Wageningen, The Netherlands han.mulder@wur.nl.
authors: Herman A
authors: HA
authors: Mulder
authors: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom.
authors: William G
authors: WG
authors: Hill
authors: TOPIGS Research Center IPG BV, 6640 AA Beuningen, The Netherlands.
authors: Egbert F
authors: EF
authors: Knol
mesh_terms: D000818:Animals; D001724:Birth Weight / Q000235:genetics*; D059647:Gene-Environment Interaction; D056084:Genetic Fitness; D014644:Genetic Variation; D008957:Models, Genetic; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic; D050497:Stillbirth / Q000235:genetics / Q000662:veterinary*; D013552:Swine / Q000235:genetics*
keywords: complex traits; fitness; genetics of environmental variance; mass selection; optimum trait
references: Genet Sel Evol. 2001 Jan-Feb;33(1):39-59
references: 11268313
references: Genetics. 1992 Dec;132(4):1187-94
references: 1459435
references: Ann Eugen. 1951 Sep;16(2):147-64
references: 14885877
references: Genet Res. 2003 Dec;82(3):207-22
references: 15134199
references: Genet Res. 2004 Apr;83(2):121-32
references: 15219157
references: Evolution. 2005 Jun;59(6):1237-44
references: 16050100
references: Philos Trans R Soc Lond B Biol Sci. 2005 Jul 29;360(1459):1513-27
references: 16108138
references: Genetics. 1943 Nov;28(6):476-90
references: 17247099
references: Genetics. 2007 Apr;175(4):1895-910
references: 17277375
references: Genet Sel Evol. 2008 Jan-Feb;40(1):37-59
references: 18096114
references: Am Nat. 2001 Mar;157(3):245-61
references: 18707288
references: Proc Biol Sci. 2009 Aug 22;276(1669):2963-9
references: 19474039
references: Genet Sel Evol. 2010 Mar 19;42:8
references: 20302616
references: Genet Res (Camb). 2010 Dec;92(5-6):381-95
references: 21429270
references: PLoS Genet. 2011 Sep;7(9):e1002295
references: 21980300
references: Anim Genet. 2012 Jul;43 Suppl 1:87-96
references: 22742506
references: PLoS Genet. 2012;8(8):e1002839
references: 22876191
references: Nature. 2012 Oct 11;490(7419):267-72
references: 22982992
references: Genet Res (Camb). 2012 Dec;94(6):307-17
references: 23374241
references: J Dairy Sci. 2013 Apr;96(4):2627-2636
references: 23415533
references: Curr Opin Biotechnol. 2013 Aug;24(4):752-9
references: 23566377
references: Genet Sel Evol. 2013 Jul 04;45:23
references: 23827014
references: Am J Hum Genet. 2013 Aug 8;93(2):390-7
references: 23910463
references: J Dairy Sci. 2013;96(11):7306-17
references: 24035025
references: Evolution. 2013 Oct;67(10):2923-35
references: 24094343
references: PLoS One. 2013 Nov 04;8(11):e79507
references: 24223957
references: Genetics. 2014 Mar;196(3):643-51
references: 24414548
references: F1000Res. 2013 Oct 02;2:200
references: 24555098
references: J Anim Sci. 2015 Mar;93(3):900-11
references: 26020868
references: Evolution. 1983 Nov;37(6):1210-1226
references: 28556011
references: Evolution. 1986 Mar;40(2):221-231
references: 28556039
references: Evolution. 1995 Apr;49(2):375-378
references: 28565003
references: Evolution. 1988 Sep;42(5):849-861
references: 28581168
references: J Anim Sci. 1997 Dec;75(12):3119-25
references: 9419984