The difference between the temperature at which DNA homoduplexes and DNA heteroduplexes undergo 50% dissociation. The statistic is often used to measure the genetic relationship between the nucleotide sequences of two or more species. A ΔT50H value can be converted into an absolute time interval if the fossil record can provide an independent dating estimate. In primates, a ΔT50H value of 1 equals about 11 million years. If repetitive sequences have been removed from the DNAs, then a ΔT50H value of 1 represents about a 1% difference in single-copy genes between the samples. See DNA clock hypothesis, reassociation kinetics.
Subjects: Genetics and Genomics.