D. simulans homolog of 13.2 kb genomic fragment of per+t13.2
D.melanogaster males whose only functional per gene is that from D.simulans sing with simulans-like (short) rhythms, though D.simulans and melanogaster forms have the same effect on activity.
Male D.melanogaster per01 flies carrying Dsim\per+t13.2 produce courtship songs with a period of about 35 seconds, characteristic of D.simulans.
Assayed in D.melanogaster.