decreased survivor rate MP:0008770 reduced viability decreased survival rate low survivor rate MPheno.ontology a smaller percentage of organisms than expected survive to adulthood and have a lifespan similar to controls reduced survival rate This term is used in conjunction with other lethality terms when the lethality is only partially expressed. For example, use this term when some individuals of a defined population die as embryos, neonates or by weaning, with some percentage of individuals surviving the lethal phase and achieving a normal life span. reduced survivor rate low survival rate lethality, incomplete penetrance