Classification By Fitness or Trait Value
Two-locus epistatic interactions can be either synergistic (enhancing the effectiveness) or antagonistic (reducing the activity). In the example of a haploid organism with genotypes (at two loci) AB, Ab, aB or ab, we can think of the following trait values where higher values suggest greater expression of the characteristic (the exact values are simply given as examples):
| AB | Ab | aB | ab | |
| No epistasis (additive across loci) | 2 | 1 | 1 | 0 |
| Synergistic epistasis | 3 | 1 | 1 | 0 |
| Antagonistic epistasis | 1 | 1 | 1 | 0 |
Hence, we can classify thus:
| Trait values | Type of epistasis |
| AB = Ab + aB − ab | No epistasis, additive inheritance |
| AB > Ab + aB − ab | Synergistic epistasis |
| AB < Ab + aB − ab | Antagonistic epistasis |
Understanding whether the majority of genetic interactions are synergistic or antagonistic will help solve such problems as the evolution of sex.
Read more about this topic: Epistasis
Famous quotes containing the words fitness and/or trait:
“Critics generally come to be critics not by reason of their fitness for this, but of their unfitness for anything else. Books should be tried by a judge and jury as though they were a crime, and counsel should be heard on both sides.”
—Samuel Butler (1835–1902)
“A trait no other nation seems to possess in quite the same degree that we do—namely, a feeling of almost childish injury and resentment unless the world as a whole recognizes how innocent we are of anything but the most generous and harmless intentions.”
—Eleanor Roosevelt (1884–1962)