In contrast, an asexual organism is a genetic clone of its female parent. The genotype is largely static for an individual during its lifetime, except when a mutation occurs. A mutation is a lesion of DNA that changes the genetic material in one allele at a locus. If the mutation occurs in a somatic cell, there will be no consequence for transmission of material across generations. However, if the mutation occurs in a cell of the germ line, which produces sperm or eggs for sexual reproduction, then the mutation can be transmitted across generations.
Mutations are the ultimate source of all genetic variation.
This includes mechanisms of development. For simplicity of analysis, we break the whole organism into phenotypic traits that are largely functional units. For example, the number of offspring that an animal produces in one bout of reproduction, termed fecundity, is a phenotypic trait related to reproduction. However, phenotypic traits are usually correlated with other phenotypic traits. For example, the number of offspring that a parent produces is related to the kind or quality of care that the parent can provide to the offspring.