Table 1.

Reproductive failure and sperm presence in inbred and random pair matings of D. nigrospiracla

Exp.	Male	Replications	No. of females	Females not ovipositing	Females with sperm
1×a	Brother	1	45	34/45 (75%)	31/34 (91%)
	Random	1	39	12/39 (31%)	7/12 (58%)
1×b	Brother	2	31	24/31 (77%)	19/24 (79%)
	Random	2	25	9/25 (36%)	5/9 (55%)
3×a	3×	1	19	13/19 (68%)	11/12 (92%)
	2×:1×	1	21	4/21 (19%)	4/4 (100%)
3×b	3×	2	12	8/12 (67%)	8/8 (100%)
	2×:1×	2	17	2/17 (12%)	2/2 (100%)

Females in experiments 1×a and 1×b were mated once, to either a male chosen at random from the mass mating culture or to their brother after one generation of sib-mating. Females in experiments 3×a and 3×b were mated three times, either all three times to the same male, a brother, or twice to their brother and then to a male chosen at random from the mass culture. All matings were observed to ensure normal copulations were achieved. Mated females were separated from males and allowed to lay eggs in yeasted vials, changed daily, for 1 week. Females not ovipositing after 1 week were dissected and examined for the presence of motile sperm.