Answer:
meiosis; chiasmata
Explanation:
The linkage between two non-sister chromatids of homologous chromosomes can be seen in the diplotene stage of prophase I of meiosis which is called chiasmata.
This phenomenon is discovered in 1909 by a Frans Janssens who called the structure chaismata. Chaismata allows the exchange of genes between two homologous chromosomes which came from two parents.
In the pachytene stage crossing over between non-sister chromatids takes place. This crossing over helps in increasing the genetic variability in the gametes and offspring.
