Meeting Abstract

37.11  Tuesday, Jan. 5  The relationship between pleiotropy and evolvability PAVLICEV, M.*; CHEVERUD, J. M.; HANSEN, T.F.; University of Oslo, Norway; Washington University, St. Louis, MO; University of Oslo, Norway pavlicev@pcg.wustl.edu

The question of what kind of genetic architecture maximizes evolvability of the system is central to the evolution of complex organisms. Modularity of pleiotropic effects has been proposed as one of the main architectural features of evolvable organisms. Thereby the lack of simultaneous genetic effects on unrelated traits is suggested to free the modules from constraints due to correlated response. However restricting the pleiotropic effects also reduces genetic variation of traits (Hansen 2003) and it is the balance of the two forces that determine the maximum evolvability of the system. The constraining covariance between unrelated traits is generated only by the pleiotropic genetic effects that are biased towards the same direction. High variability of pleiotropy across loci with respect to sign can thus diminish the constraining genetic correlation and increase evolvability in spite of pleiotropy, while retaining the variance. Nevertheless, even this so-called antagonistic pleiotropy has been shown to be disadvantageous if there are correlated effects on variances of the traits (Baatz and Wagner 1997). The advantages and disadvantages of different pleiotropic architectures are complex. Here we explore the distribution of pleiotropy in the empirical data, using QTL based effects, measured for 11 differently related morphological traits in an intercross of two mouse strains, large (LG/J) and small (SM/J).