darker pigmentation. Larvae with these traits have a higher chance of survival when exposed to the predators, but grow more slowly than other phenotypes. Genetic canalization In contrast to phenotypic plasticity, the concept of genetic canalization addresses the extent to which an organism's phenotype allows conclusions about its genotype. A phenotype is said to be canalized if mutations (changes in the genome) do not noticeably affect the physical properties of the organism. This means that a canalized phenotype may form from a large variety of different genotypes, in which case it is not possible to exactly predict the genotype from knowledge of the phenotype (i.e. the genotype–phenotype map is not invertible). If canalization is not present, small changes in the genome have an immediate effect on the phenotype that develops. Importance to evolutionary biology According to Lewontin, the theoretical task for population genetics is a process in two spaces: a "genotypic space" and a "phenotypic space". The challenge of a complete theory of population genetics is to provide a set of laws that predictably map a population of genotypes (G1) to a phenotype space (P1), where selection takes place, and another set of laws that map the resulting population (P2) back to genotype space (G2) where Mendelian genetics can predict the next generation of genotypes, thus completing the cycle. Even if non-Mendelian aspects of molecular genetics are ignored, this is a gargantuan task. Visualizing the transformation schematically: (adapted from Lewontin 1974, p. 12). T1 represents the genetic and epigenetic laws, the aspects of functional biology, or development, that transform a genotype into phenotype. This is the "genotype–phenotype map". T2 is the transformation due to natural selection, T3 are epigenetic relations that predict genotypes based on the selected phenotypes and finally T4 the rules of Mendelian genetics. In practice, there are two bodies of evolutionary theory that exist in parallel, traditional population genetics operating in the genotype space and the biometric theory used in plant and animal breeding, operating in phenotype space. The missing part is the mapping between the genotype and phenotype space. This leads to a "sleight of hand" (as Lewontin terms it) whereby variables in the equations of one domain, are considered parameters or constants, where, in a full-treatment, they would be transformed themselves by the evolutionary process and are functions of the state variables in the other domain. The "sleight of hand" is assuming that the mapping