Relating to or denoting an allele or chromosomal abnormality which impairs the viability of most of the individuals homozygous for it.
Example sentencesExamples
Pokey (pok), a sex-linked recessive semi-lethal gene in Tribolium castaneum has been described.
Some of the genes that gives the mouse its common colours or markings also makes the mouse sick, or unfit to live. These genes are called semi-lethal or lethal.
A chief difficulty in arguing for macroevolution by mutations is the fact that most expressed mutations are either lethal or semi-lethal.