modularity
Hill WG & Zhang X-S 2012 On the pleiotropic structure of the genotype-phenotype map and the evolvability of complex organisms. Genetics, in press.
- Wagner and Zhang (2011) discuss the magnitude of pleiotropy for complex or quantitative traits
- they argue that it is highly restricted
- rather few traits are influenced by each gene
- there is more opportunity for evolutionary change according to Fisher's (1930) geometric model than suggested by the analyses of Orr (2000)
- Wagner and Zhang's second quantitative conclusion was that genes affecting more traits have larger per-trait effects
- their third conclusion was that there was strong modularity of effects
- other data which indicate substantial pleiotropy have, however, been published
- many studies have been undertaken in D. melanogaster by Mackay and colleagues
- we consider that there are a number of important assumptions in the analyses by Wagner, Zhang and colleagues which lead us to question their general conclusions on the degree of modularity and pleiotropy
- many real effects were likely to be missed
